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Other glossaries of fisheries terms are available from North Carolina Division of Marine Fisheries and from the United Nations Fisheries and Agriculture Organization.
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A-run steelhead -- Summer steelhead crossing Bonneville Dam on or before August 25.

Abatement -- Reducing the degree or intensity of, or eliminating, pollution.

Abdominal pelvics -- Pelvic fins located on the abdomen far behind the pectoral fins; pelvic bones do not attach to pectoral girdle.

Abiota -- Those non-living factors which are present in and affect the characteristics of a given ecosystem.

Ablation -- The process by which ice and snow waste away as a result of melting and/or evaporation.

Absolute Recruitment -- The number of fish which grow into the catchable size range in a unit of time (usually a year).

Abundance Index -- Information obtained from samples or observations and used as a measure of the weight or number of fish which make up a stock.

Accessory pelvic appendage -- A tapered fleshy lobe above the base of the pelvic fin.

Acclimate -- The adaptation of an organism to environmental changes.

Acclimation pond -- Concrete or earthen pond or a temporary structure used for rearing and imprinting juvenile fish in the water of a particular stream before their release into that stream.

Acid Rain -- Rainfall with a pH of less than 7.0. Long-term deposition of these acids is linked to adverse effects on aquatic organisms and plant life in areas with poor neutralizing (buffering) capacity.

Acidic -- The condition of water or soil that contains a sufficient amount of acid substances to lower the pH below 7.0.

Acre -- A measure of area equal to 43,560 square feet (4,046.87 square meters). One square mile equals 640 acres.

Acre-foot (af) -- The volume of water that will cover one acre to a depth of 1 foot.

Adaptation -- Changes in an organism's structure or habits that allow it to adjust to its surroundings.

Adaptive management -- The process of implementing policy decisions as scientifically driven management experiments that test predictions and assumptions in management plans, and using the resulting information to improve the plans.

Adaptive management areas -- Landscape units designated for development and testing of technical and social approaches to achieving desired ecological, economic, and other social objectives.

Adfluvial -- Possessing a life history trait of migrating between lakes or rivers and streams.

Adipose fin -- A small fleshy fin with no rays, located between the dorsal and caudal fins.

Adult equivalent population -- The number of fish that would have returned to the mouth of the Columbia River in the absence of any prior harvest.

Adult Fish Counts -- A fish-viewing window is at the upstream end of most fish ladders. Observers count the number of fish, by species and size, passing the window for 50 minutes of every hour for 16 hours per day. Extrapolations are made for the hours and minutes not counted to provide an estimate of daily adult fish passage for each dam. In general, separate counts are made for adults and jacks (precocious males that can be identified by their smaller size).

Adult Fish Ladders -- The main-stem hydroelectric dams on the Columbia and lower Snake Rivers have fish ladders that allow adults to pass the dams on their upstream spawning migration.

Aeration -- Any active or passive process by which intimate contact between air and liquid is assured, generally by spraying liquid in the air, bubbling air through water, or mechanical agitation of the liquid to promote surface absorption of air.

Aeration Tank -- A chamber used to inject air into water.

Aerobic -- Characterizing organisms able to live only in the presence of air or free oxygen, and conditions that exist only in the presence of air or free oxygen. Contrast with Anaerobic.

Affluent (Stream) -- A stream or river that flows into a larger one; a Tributary.

Age -- The number of years of life completed, here indicated by an arabic numeral, followed by a plus sign if there is any possibility of ambiguity (age 5, age 5+)1.

Age specific survival rate -- The average proportion of individuals in a particular are group that survive for a given period.

Age-class -- A group of individuals of a certain species that have the same age.

Ageing -- "A fish that is less than 1 year old (counted from time of spawning by its parents) is considered a subyearling, or zero-age. A yearling fish is more than 1 year and less than 2 years old. Adult ages are also reckoned from time of egg deposition and are typically based on counts of annual rings on scales or otoliths (a calcareous ""earstone"" found in the internal ear of fishes). The age of an adult is sometimes estimated by length."

Alevin -- The developmental life stage of young salmonids and trout that are between the egg and fry stage. The alevin has not absorbed its yolk sac and has not emerged from the spawning gravels.

Allele -- An alternate form of a gene.

Allocation -- Division of the fish resource among harvesters and needs for reproduction

Allopatric -- Occurring in different geographic regions. See parapatric and sympatric.

Allozymes -- Alternate forms of an enzyme produced by different alleles and often detected by protein electrophoresis.

Alluvial -- Deposited by running water.

Alluvium -- Sediment or loose material such as clay, silt, sand, gravel, and larger rocks deposited by moving water.

Alternative -- One of several policies, plans, or projects proposed for making decisions.

Anabranch -- A diverging branch of a river which re-enters the main stream.

Anadromous -- Fish that hatch rear in fresh water, migrate to the ocean (salt water) to grow and mature, and migrate back to fresh water to spawn and reproduce.

Anal fin -- The fin located on the ventral median line and behind the anus.

Analytical watershed -- For planning purposes, a drainage basin subdivision used for analyzing cumulative impacts on resources.

Anerobic -- Characterizing organisms able to live and grow only where there is no air or free oxygen, and conditions that exist only in the absence of air or free oxygen.

Angler day -- One person angling for any part of 1 day.

Annual (or seasonal) Total Mortality Rate -- The number of fish which die during a year (or season), divided by the initial number. Also called; actual mortality rate, *coefficient of mortality .

Annual operating plan -- A yearly plan for operating reservoirs on the Columbia River. Such a plan is specifically required by the Columbia River Treaty and by the Pacific Northwest Coordination Agreement.

Annulus -- A mark or ring that forms annually on the otoliths, scales, and other bones of fish, that correspond to the annual period of slow growth that fish go through. Annuli are used by fish managers to determine age and growth of fish.

Approach velocities -- Water velocities at or near the face of a fish screen.

Appropriate -- To authorize the use of a quantity of water to an individual requesting it.

Aquaculture -- The controlled cultivation and harvest of aquatic plants or animals (e.g., edible marine algae, clams, oysters, and salmon).

Aquaduct -- A pipe or conduit made for bringing water from a source.

Aquatic ecosystem -- Any body of water, such as a stream, lake or estuary, and all organisms and nonliving components within it, functioning as a natural system.

Aquatic habitat -- Habitat that occurs in free water.

Aquifer -- An underground layer of rock or soil containing ground water.

Arch Dam -- Curved masonry or concrete dam, convex in shape upstream, that depends on arch action for its stability; the load or water pressure is transferred by the arch to the Abutments.

Artificial production -- (or Artificial propagation) Spawning, incubating, hatching or rearing fish in a hatchery or other facility constructed for fish production.

Artificial propagation -- Any assistance provided by man in the reproduction of Pacific salmon. This assistance includes, but is not limited to, spawning and rearing in hatcheries, stock transfers, creation of spawning habitat, egg bank programs, captive broodstock programs, and cryopreservation of gametes.

Assessment level -- Categories of the level of complexity of and data available for each assessment included in this document; index of abundance (INDEX), yield-per-recruit analysis (YIELD), analysis of the age structure of the catch (AGE STRUCTURE), analysis including the relationship between recruitment and spawning stock size (SPAWNING STOCK) and assessment that allows prediction of future (one or two years ahead) stock sizes and catches (predictive). These levels are detailed in the subsection titled Kinds of Assessments.

At-risk fish stocks -- Stocks of anadromous salmon and trout that have been identified by professional societies, fish management agencies, and in the scientific literature as being in need of special management consideration because of low or declining populations.

Attraction -- Drawing fish to dam fishways or spillways through the use of water flows.

Augmentation (of stream flow) -- Increasing steam flow under normal conditions, by releasing storage water from reservoirs.

Availability -- 1. The fraction of a fish population which lives in regions where it is susceptible to fishing during a given fishing season . This fraction receives recruits from or becomes mingled with the non-available part of the stock at other seasons, or in other years. (Any more or less completely isolated segment of the population is best treated as a separate stock.) 2. Catch per unit of effort.

Average megawatt (aMW) -- The average amount of energy (in megawatts) supplied or demanded over a specified period of time; equivalent to the energy produced by the continuous operation of one megawatt of capacity over the specified period.

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B-run steelhead -- Summer steelhead crossing Bonneville Dam after August 25.

Biological reference points -- Fishing mortality rates that may provide acceptable protection against growth overfishing and/or recruitment overfishing for a particular stock. They are usually calculated from equilibrium yield-per-recruit curves, spawning stock biomass-per-recruit curves and stock recruitment data. Examples are F0.1, Fmax and Fmed.

Biomass -- The total quantity (at any given time) of living organisms of one or more species per unit of space (species biomass), or of all the species in a biotic community (community biomass).

Birth-pulse population -- A population assumed to produce all of its offspring at an identical and instantaneous point during the annual cycle.

Blocked areas -- Areas in the Columbia River Basin where hydroelectric projects have created permanent barriers to anadromous fish runs. These include the areas above Chief Joseph and Grand Coulee dams, the Hells Canyon Complex and other smaller locations.

Blowdown -- Trees felled by high winds.

Board feet (BF) -- Lumber or timber management term. The amount of wood contained in an unfinished board 1 inch think, 12 inches long, and 12 inches wide.

Bog -- Freshwater wetlands that are poorly drained and characterized by a buildup of peat.

Bonneville Power Administration (Bonneville) -- The sole federal power marketing agency in the Northwest and the region's major wholesaler of electricity. Created by Congress in 1937, Bonneville sells power to public and private utilities, direct service customers, and various public agencies in the states of Washington, Oregon, Idaho, Montana west of the Continental Divide, (and parts of Montana east of the Divide) and smaller adjacent areas of California, Nevada, Utah and Wyoming. The Northwest Power Act charges Bonneville with additional duties related to energy conservation, resource acquisition, and fish and wildlife.

Boreal Forest -- A northern forest, as in the boreal forest Biome, characterized by evergreen conifers and long winters. The boreal forest, also referred to as a Taiga, is found in the northern parts of North America, Europe, and Asia.

Bottleneck -- A sharp reduction of a breeding population's size to a few individuals. The genetic consequences of a bottleneck, especially the loss of genetic variability, depend on both its magnitude and its duration.

Boulder -- A large substrate particle that is larger that cobble, >256 mm in diameter.

Brackish -- Having a somewhat salty taste, especially from containing a mixture of seawater and fresh water.

Brackish Water -- Generally, water containing dissolved minerals in amounts that exceed normally acceptable standards for municipal, domestic, and irrigation uses. Considerably less saline than sea water. Also, Marine and Estuarine waters with Mixohaline salinity (0.5 to 30 due to ocean salts). Water containing between 1,000-4,000 parts per million (PPM) Total Dissolved Solids TDS). The term brackish water is frequently interchangeable with Saline Water. The term should not be applied to inland waters.

Braided stream -- A complex tangle of converging and diverging stream channels (Anabranches) separated by sand bars or islands. Characteristic of flood plains where the amount of debris is large in relation to the discharge.

Braiding (of River Channels) -- Successive division and rejoining of riverflow with accompanying islands.

Brood stock -- Adult fish used to propagate the subsequent generation of hatchery fish.

Brood year -- The year in which the eggs were spawned

Broodline -- The generation of pink salmon that reproduces every other year. Because of the lack of variable age structure in this species, even-year pink salmon are reproductively isolated from odd-year pink salmon.

Brook -- A natural stream of water, smaller than a river or creek; especially a small stream or rivulet which breaks directly out of the ground, as from a spring or seep; also, a stream or torrent of similar size, produced by copious rainfall, melting snow and ice, etc.; a primary stream not formed by tributaries, though often fed below its source, as by rills or runlets; one of the smallest branches or ultimate ramifications of a drainage system.

Buccal -- Pertaining to the cheeks or the cavity of the mouth.

Buffer strip -- A barrier of permanent vegetation, either forest or other vegetation, between waterways and land uses such as agriculture or urban development, designed to intercept and filter out pollution before it reaches the surface water resource.

Buoyancy -- The tendency of a body to float or rise when submerged in a fluid.

Bureau of Reclamation -- An agency that administers some parts of the federal program for water resource development and use in western states. The Bureau of Reclamation owns and operates a number of dams in the Columbia River Basin, including Grand Coulee and several projects on the Yakima River.

Button-up fry -- A salmonid fry that has not completely absorbed its yolk sac and has emerged from its spawning gravel.

Buttress Dam -- A dam consisting of a watertight upstream face supported at intervals on the downstream side by a series of buttresses.

Bypass system -- A channel or conduit in a dam that provides a route for fish to move through or around the dam without going through the turbine units.

Bypass Systems -- Juvenile salmonid bypass systems consist of moving screens lowered into turbine intakes to divert fish away from turbines at hydroelectric dams. Fish move into a channel that transports them safely around the dam. Bypassed fish are then typically returned directly to the river below the dam, although some Columbia River Basin dams have facilities to load bypassed fish into barges or trucks for transport to a release site downstream from all the dams. PIT-tag detectors interrogate all PIT-tagged fish passing through the bypass system. In addition, the systems are equipped with subsampling capabilities that allow hands-on enumeration and examination of a portion of the collection for coded-wire tags (CWT), brands, species composition, injuries, etc. Recovery information at bypass systems is used to develop survival estimates, travel time estimates, and run timing; to identify problem areas within the bypass system; and as the basis for flow management decisions during the juvenile migrations.

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Canal -- A constructed open channel for transporting water.

Canopy -- A layer of foliage in a forest stand. This most often refers to the uppermost layer of foliage, but it can be used to describe lower layers in a multistoried stand. Leavs, branches and vegetation that are above ground and/or water that provide shade and cover for fish and wildlife.

Canopy closure -- The degree to which the canopy (forest layers above one's head) blocks sunlight or obscures the sky.

Captive brood stock -- Fish raised and spawned in captivity.

Captive broodstock program -- A form of artificial propagation involving the collection of individuals (or gametes) from a natural population and the rearing of these individuals to maturity in captivity. For listed species, a captive broodstock is considered part of the evolutionarily significant unit (ESU) from which it is taken.

Carnivorous -- Feeding on animal tissues.

Carrying capacity -- The maximum number of organisms that a certain habitat can sustain over the long term.

Cartilaginous fishes -- A major group of fishes including sharks and rays.

Cascade -- A short, steep drop in stream bed elevation often marked by boulders and agitated white water.

Catadromous -- Refers to fishes that migrate from fresh water to salt water to spawn or reproduce such as the American eel.

Catch -- The act of landing a fish at which point the fisher has the option of releasing or retaining it.

Catch Curve -- A graph of the logarithm of number of fish taken at successive ages or sizes.

Catch Per Unit Of Effort -- The catch of fish, in numbers or in weight, taken by a defined unit of fishing effort. Also called; catch per effort, fishing success, availability.

Catch rate (Harvest rate) -- The time spent to catch fish expressed as catch in numbers or pounds per unit of effort.

Catchability -- "The fraction of a fish stock which is caught by a defined unit of the fishing effort. When the unit is small enough that it catches only a small part of the stock -- 0.01 or less--it can be used as an instantaneous rate in computing population change. (For fractions taken of various portions of the stock, see ""vulnerability."") Also called; catchability coeificient, *force of fishing mortality"

Catchment -- (1) The catching or collecting of water, especially rainfall. (2) A reservoir or other basin for catching water. (3) The water thus caught.

Caudal -- Pertaining to the tail.

Caudal fin -- The tail fin.

Caudal peduncle -- The tapering portion of a fish's body between the posterior edge of the anal fin base and the base of the caudal fin.

Ceratomyxa shasta -- A freshwater myxosporean parasite of salmonids that causes high mortalities in susceptible strains of fish. Other common diseases of Pacific salmon include vibriosus, cold water disease, bacterial kidney disease, and furunculosis.

Ceremonial or Subsistence harvest -- Harvests of fish by Native Americans for ceremonies and to support traditional lifestyles.

Channel -- An area that contains continuously or periodically flowing water that is confined by banks and a stream bed.

Channelization -- The process of changing and straightening the natural path of a waterway.

Check dam -- A small dam constructed in a gully or other small water course to decrease the streamflow velocity, minimize channel erosion, promote deposition of sediment and to divert water from a channel.

Chinook wind -- A warm dry wind on the east side of the Rocky Mountains.

Chromosome -- A thread-like structure containing many genes.

Classic old growth -- Forest stands with unusually old and large trees that also meet criteria for old-growth forest.

Clay -- Substrate particles that are smaller than silt and generally less than 0.004 mm in diameter.

Clear-cut -- A harvest in which all or almost all of the trees are removed in one cutting.

Clear-cut harvest -- A timber harvest method in which all trees are removed in a single entry from a designated are, with the exception of wildlife trees or snags, to create an even-aged stand.

Climax -- The culminating stage in plant succession for a given site where the vegetation has reached a highly stable condition.

Co-managers -- Federal, state, county, local, and tribal agencies that cooperatively manage salmonids in the Pacific Northwest.

Coarse woody debris (CWD) -- Portion of a tree that has falled or been cut and left in the woods. Usually refers to pieces at least 20 inches in diameter.

Coastal Cutthroat Trout -- A cutthroat trout of the subspecies Oncorhynchus clarki clarki. The subspecies is primarily found in the coastal region of northwestern North America and is the only anadromous subspecies of O. clarki.

Cobble -- Substrate particles that are smaller than boulders and are generally 64-256 mm in diameter. Can be further classified as small and large cobble. Commonly used by salmon in the construction of a redd.

Coded-wire tag (CWT) -- A small (0.25mm diameter x 1 mm length) wire etched with a distinctive binary code and implanted in the snout of s salmon or steelhead, which, when retrieved, allows for the identification of the origin of the fish bearing the tag.

Coefficient of determination (r-squared) -- The percentage of variation of the independent variable (y) that is attributed to its linear regression in the dependent variable (x).

Coefficient of variation -- A statistical term describing the percentage variation in a population.

Cohort -- Individuals all resulting from the same birth-pulse, and thus all of the same age.

Collection and bypass system -- A system at a dam that collects and holds the fish approaching the dam for later transportation or moves them through or around the dam without going through the turbine units.

Colonization -- The establishment of a species in an area not currently occupied by that species. Colonization often involves dispersal across an area of unsuitable habitat.

Columbia basin fish and wildlife authority -- Represents regional state and federal fish agencies and the Columbia Basin Indian Tribes.

Columbia River Compact -- An interstate compact between the states of Oregon and Washington by which the states jointly regulate fish in the Columbia River.

Columbia River Inter-Tribal Fish Commission -- The Commission is the coordinating body of the Yakima, Nez Perce, Umatilla and Warm Springs Indian tribes. These tribes all signed the 1855 treaties that reserved their rights to Columbia River salmon and steelhead, certain wildlife and other resources.

Columbia River System -- The Columbia River and its tributaries.

Columbia River Treaty -- The treaty between the United States and Canada for the joint development of the Columbia River. It became effective on September 16, 1964.

Commercial fishery (or harvest) -- A fishery, using various types of fishing gear, that is intended to harvest one or more species of fish for the purpose of selling them to fish buyers or directly to the public.

Commercial forest land -- Land declared suitable for producing timber crops and not withdrawn from timber production for other reasons.

Commercial thinning -- The removal of generally merchantable trees from an even-ages stand, usually to encourage growth of the remaining trees.

Commercial tree species -- Conifer species used to calculate the commercial forest land allowable sale quantity. They are typically utilized as saw timber and include species such as Douglas-fir, hemlock, spruce, fir, pine, and cedar.

Commodity resources -- Goods or products of economic use or value.

Compensation -- Management activities that replace all or part of fish stocks or their habitat lost through development or other activities.

Conditional Fishing Mortality Rate -- The fraction of an initial stock which would be caught during the year (or season) if no other causes of mortality operated. (Also called fishing mortality rate).

Conditional Natural Mortality Rate -- The fraction of an initial stock that would die from causes other than fishing during a year (or season), if there were no fishing mortality. Also called; annual natural mortality rate, seasonal natural mortality rate.

Confluence -- (1) The act of flowing together; the meeting or junction of two or more streams; also, the place where these streams meet. (2) The stream or body of water formed by the junction of two or more streams; a combined flood.

Conifer -- A tree belonging to the order Gymnospermae, comprising a wide range of trees that are mostly evergreens. Conifers bear cones (hence, coniferous) and needle-shaped or scalelike leaves.

Coniferous -- Pertaining to Conifers, which bear woody cones containing naked seeds.

Conservation -- The process or means of achieving recovery of viable populations.

Conservation area -- Designated land where conservation strategies are applied for the purpose of attaining a viable plant or animal population.

Conservation recommendations -- Suggestions by the Fish and Wildlife Service or National Marine Fisheries Service in biological opinions regarding discretionary measures to minimize or avoid adverse effects on a proposed action of federally listed threatened or endangered species or designated critical habitat.

Conservation strategy -- A management plan for a species, group of species, or ecosystem that prescribes standards and guidelines that if implemented provide a high likelihood that the species, groups of species, or ecosystem, with its full complement of species and processes, will continue to exist well-distributed throughout a planning area, i.e., a viable population.

Contaminate -- To make impure or unclean by contact or mixture.

Contiguous habitat -- Habitat suitable to support the life needs of species that is distributed continuously or nearly continuously across the landscape.

Core area -- The area of habitat essential in the breeding, nesting and rearing of young, up to the point of dispersal of the young.

Corps of Engineers (U.S. Army) -- An agency with the responsibility for design, construction and operation of civil works, including multipurpose dams and navigation projects.

Correlation coefficient ® -- A statistical expression that varies between -1 and +1 depending upon how close the variables measured in a population are related. With perfect correlation, r = 1.

Corridor -- A defined tract of land, usually linear, through which a species must travel to reach habitat suitable for reproduction and other life-sustaining needs.

Cover -- Vegetation used by wildlife for protection from predators, or to mitigate weather conditions, or to reproduce. May also refer to the protection of the soil and the shading provided to herbs and forbs by vegetation.

Creel census survey -- The collection of data concerning the number of fish caught by sport fishers on a particular stream or in a particular area.

Critical habitat -- Under the Endangered Species Act, critical habitat is defined as (1) the specific areas within the geographic area occupied by a federally listed species on which are found physical and biological features essential to the conservation of the species, and that may require special management considerations or protections; and (2) specific areas outside the geographic area occupied by a listed species, when it is determined that such areas are essential for the conservation of the species.

Critical Size -- The average size of the fish in a year-class at the time when the instantaneous rate of natural mortality equals the instantaneous rate of growth in weight for the year-class as a whole. Also called; *optimum size.

Critical stock -- A stock of fish experiencing production levels that are so low that permanent damage to the stock is likely or has already occurred.

Crossbreeding -- "Reproduction between two distinct conspecific gene pools (compare with ""hybridization,"" which generally refers to reproduction between distinct species or higher taxa). With respect to listed species of Pacific salmon, crossbreeding generally refers to interbreeding between individuals from different evolutionarily significant units (ESUs)."

Crown -- The upper part of a tree or other woody plant that carries the main system of branches and the foliage.

Crown cover -- The degree to which the crowns of trees are nearing general contact with one another.

Crucial habitat -- Habitat that is basic to maintaining viable populations of fish and wildlife during certain seasons of the year or specific reproduction periods.

Crude density -- The number of individuals in an area.

Cryopreservation -- Preservation of gametes at very low temperature (e.g., use of liquid nitrogen to freeze sperm for later propagative use).

Ctenoid -- Having a comb-like margin.

Ctenoid scales -- A type of fish scale that has spines or ctenii on the posterior or exposed portion, found on bass, walleye, and other fish.

Cubic feet per second (Cfs) -- A unit used to measure water flow. One cfs is equal to 449 gallons per minute.

Cull -- A tree or snag that does not meet merchantable specifications.

Cultured stock -- A stock that depends upon spawning, incubation, hatching, or rearing in a hatchery or other artificial production facility.

Culvert -- A buried pipe that allows streams, rivers, or runoff to pass under a road.

Cumulative Effects -- The combined environmental impacts that accrue over time and space from a series of similar or related individual actions, contaminants, or projects.

Cycloid scales -- Smooth, flat, round scales that have concentric lines called circuli, found on trout, herring, and other fish.

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Dam -- A concrete or earthen barrier constructed across a river and designed to control water flow or create a reservoir.

Debris flow -- A rapid moving mass of rock fragments, soil, and mud, with more that half of the particles being larger that sand size.

Debris torrent -- Rapid movement of a large quantity of materials (wood and sediment) down a stream channel during storms or floods. This generally occurs in smaller streams and results in scouring of streambed.

Deciduous -- Trees and plants that shed their leaves at the end of the growing season.

Deciduous Plant -- (Botanical) (1) Plants characterized by a specific growth and dormancy cycle, with certain parts falling at the end of the growing period, as leaves, fruits, etc., or after anthesis, as the petals of many flowers. (2) Plants having leaves of this type. As contrasted with Evergreen which remains verdant throughout the year.

Decomposer -- Any of various organisms (as many bacteria and fungi) that feed on and break down organic substances (such as dead plants and animals).

Decomposition -- The breakdown of matter by bacteria and fungi, changing the chemical makeup and physical appearance of materials.

Deflector screens/diversion screens -- Wire mesh screens placed at the point where water is diverted from a stream or river. The screens keep fish from entering the diversion channel or pipe.

DEIS -- Draft Environmental Impact Statement.

Demand -- The rate at which electric energy is used, whether at a given instant, or averaged over any designated period of time.

Demography -- The study of characteristics of human populations, especially size, density, growth, distribution, migration and vital statistics and the effect of these on social and economic conditions.

Dendrogram -- A branching diagram, sometimes resembling a tree, that provides one way of visualizing similarities between different groups or samples.

Density (Biological population) -- The number or size of a population in relation to some unit of space.

Density-dependent -- A process, such as fecundity, whose value depends on the number of animals in the population per unit area.

Depressed stock -- A stock of fish whose production is below expected levels based on available habitat and natural variations in survival levels, but above the level where permanent damage to the stock is likely.

Descaling -- A condition in which a fish has lost a certain percentage of scales.

Detritus -- Undissolved organic and inorganic matter, such as small pieces of vegetation, and animal remains, that result from decomposition and help form the base of the food chain.

Dewatering -- Elimination of water from a lake, river, stream, reservoir, or containment.

Dike -- (1) (Engineering) An embankment to confine or control water, especially one built along the banks of a river to prevent overflow of lowlands; a levee. (2) A low wall that can act as a barrier to prevent a spill from spreading. (3) (Geology) A tabular body of igneous (formed by volcanic action) rock that cuts across the structure of adjacent rocks or cuts massive rocks.

Dip-net fishery -- A traditional tribal fishery for salmon and steelhead where fish are captured using long-handled dip nets, usually at waterfalls or other obstructions, which congregate the fish and make them more vulnerable to harvest.

Discharge -- Volume of water released from a dam or powerhouse at a given time, usually expressed in cubic feet per second.

Dissolved gas concentrations -- The amount of chemicals normally occurring as gases, such as nitrogen and oxygen, that are held in solution in water, expressed in units such as milligrams of the gas per liter of liquid. Supersaturation occurs when these solutions exceed the saturation level of the water (beyond 100 percent).

Dissolved Oxygen (DO) -- The amount of free (not chemically combined) oxygen dissolved in water, wastewater, or other liquid, usually expressed in milligrams per liter, parts per million, or percent of saturation.

Distal -- Away from the point of attachment or origin.

Distribution (of a species) -- The spatial arrangement of a species within its range.

Disturbance -- A force that causes significant change in structure and/or composition through natural events such as fire, flood, wind, or earthquake, mortality caused by insect or disease outbreaks, or by human-caused events, e.g., the harvest of forest products.

Ditch -- A long narrow trench or furrow dug in the ground, as for irrigation, drainage, or a boundary line.

Diversion -- The transfer of water from a stream, lake, aquifer, or other source of water by a canal, pipe, well, or other conduit to another watercourse or to the land, as in the case of an irrigation system.

Diversion channel -- (1) An artificial channel constructed around a town or other point of high potential flood damages to divert floodwater from the main channel to minimize flood damages. (2) A channel carrying water from a diversion dam.

Diversion Dam -- A barrier built to divert part or all of the water from a stream into a different course.

DNA (deoxyribonucleic acid) -- DNA is a complex molecule that carries an organism s heritable information. The two types of DNA commonly used to examine genetic variation are mitochondrial DNA (mtDNA), a circular molecule that is maternally inherited, and nuclear DNA, which is organized into a set of chromosomes. See also allele, electrophoresis, and transferrin.

Dorsal -- Pertaining to the back, or situated near to or on the back.

Dorsal fin -- The fin located on the back of fishes, and in front of the adipose fin, if it is present.

Dorsal fin ray -- Refers to one of the cartilaginous rays (stiff rods) located in the membrane of a dorsal fin.

Down log -- Portion of a tree that has fallen or been cut and left in the woods.

Draft -- Release of water from a storage reservoir.

Drainage -- An area (basin) mostly bounded by ridges or other similar topographic features, encompassing part, most, or all of a watershed and enclosing some 5,000 acres.

Drainage area -- See watershed.

Drawdown -- The release of water from a reservoir for power generation, flood control, irrigation or other water management activity.

Dredging -- Digging up and removing material from wetlands or waterways, usually to make them deeper or wider.

Drought -- Generally, the term is applied to periods of less than average or normal precipitation over a certain period of time sufficiently prolonged to cause a serious hydrological imbalance resulting in biological losses (impact flora and fauna ecosystems) and/or economic losses (affecting man). In a less precise sense, it can also signify nature's failure to fulfill the water wants and needs of man.

Dry Wash -- A streambed that carries water only during and immediately following rainstorms.

Duff layer -- The layer of loosely compacted debris underlying the litter layer on the forest floor.

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Early seral stage forest -- Stage of forest development that includes seedling, sapling, and pole-sized trees.

Earthfill or Earth Dam -- An embankment dam in which more than 50 percent of the total volume is formed of compacted fine-grained material obtained from a borrow area (i.e., excavation pit).

East-side forest -- The 12 National Forests in Washington, Oregon, and California that lie partly or wholly east of the Cascade Mountain Range crest: Colville, Deschutes, Fremont, Klamath, Malheur, Ochoco, Okanogan, Shasta-Trinity, Umatilla, Wallowa-Whitman, Wenatchee, and Winema National Forest.

Ecological Health -- The state of an ecosystem in which processes and functions are adequate to maintain diversity of biotic communities commensurate with those initially found there.

Ecological interaction -- The sum total of impacts of one species on another species, or on other members of the same species.

Ecologically significant -- Species, stands, and forests considered important to maintain the structure, function, and processes of particular ecosystems.

Ecosystem -- The biological community considered together with the land and water that make up its environment. Or a unit comprising interacting organisms considered together with their environment.

Ecosystem diversity -- The variety of species and ecological processes that occur in different physical settings.

Ecosystem management -- A strategy or plan to manage ecosystems to provide for all associated organisms, as opposed to a strategy or plan for managing individual species.

Eddy -- A circular current of water, usually resulting from an obstruction.

Edge -- Where plant communities meet or where successional stages or vegetative conditions with plant communities come together.

Edge effect -- "The drastically modified environmental conditions along the margins, or ""edges,"" of forest patches surrounded partially or entirely by harvested lands."

Effeciveness Of Fishing -- A general term referring to the percentage removal of fish from a stock, but not as specifically either rate of exploitation or instantaneous rate of fishing.

Effective old-growth forest -- Old-growth forest largely unmodified by external environmental influences from nearby, younger forest stands.

Effluent -- (1) Something that flows out or forth, especially a stream flowing out of a body of water. (2) (Water Quality) Discharged wastewater such as the treated wastes from municipal sewage plants, brine wastewater from desalting operations, and coolant waters from a nuclear power plant.

Egg take -- The number of eggs taken at hatcheries when adult salmon and steelhead are spawned.

Egg-to-smolt survival -- The numerical difference between the number of fertilized eggs produced by a groups of fish and the number of smolts resulting from those eggs.

EIS -- Environmental Impact Statement.

El niño current -- An intermittent warm water current that originates from the tropics and overrides the normal cold water currents that persist along the Pacific coast, resulting in warmer than normal ocean conditions.

Electrophoresis -- A technique that allows biologists to determine fish origins by analyzing the genetic variation in fish body fluid and muscle tissue. The technique is used to determine which stocks are being caught in ocean fisheries in order to better regulate ocean fishing.

Electrophoresis-2 -- Electrophoresis refers to the movement of charged particles in an electric field. It has proven to be a very useful analytical tool for biochemical characters because molecules can be separated on the basis of differences in size or net charge. Protein electrophoresis, which measures differences in the amino acid composition of proteins from different individuals, has been used for over 2 decades to study natural populations, including all species of anadromous Pacific salmonids. Because the amino acid sequence of proteins is coded for by DNA, data provided by protein electrophoresis provide insight into levels of genetic variability within populations and the extent of genetic differentiation between them.

Elevation -- Height in feet above sea level.

Emarginate -- Having the margin notched.

Embankment -- An artificial deposit of material that is raised above the natural surface of the land and used to contain, divert, or store water, support roads or railways, or for other similar purposes.

Embankment Dam -- A dam structure constructed of fill material, usually earth or rock, placed with sloping sides and usually with a length greater than its height.

Embeddedness -- The degree to which dirt is mixed in with spawning gravel.

Embryo -- The early stages of development before an organism becomes self supporting.

Emergence -- The process during which fry leave their gravel spawning nest and enter the water column.

Emigration -- Referring to the movement of organisms out of an area. See immigration and migrating.

Empirical -- (Statistics) Based on experience or observations, as opposed to theory or conjecture.

Endangered species -- Any species of plant of animal defined through the Endangered Species Act as being in danger of extinction throughout all or a significant portion or its range, and published in the Federal Register.

Endangered Species Act (ESA) -- A 1973 Act of Congress that mandated that endangered and threatened species of fish, wildlife, and plants be protected and restored.

Endemic -- Native to or limited to a specific region.

Energy -- The ability to work (i.e., exert a force over distance). Energy is measured in calories, joules, KWH, BTUs, MW-hours, and average MWs.

Energy content curves (ECC) -- A set of curves that establishes limits on the amount of reservoir draw-down permitted to produce energy in excess of FELCC.

Enhancement -- Emphasis on improving the value of particular aspects of water and related land resources.

Entrainment -- (Streams) The incidental trapping of fish and other aquatic organisms in the water, for example, used for cooling electrical power plants or in waters being diverted for irrigation or similar purposes.

Environmental analysis -- An analysis of alternative actions and their predictable short-term and long-term environmental effects, incorporating physical, biological, economic, and social considerations.

Environmental assessment (EA) -- A systematic analysis of site-specific activities used to determine whether such activities have a significant effect on the quality of the human environment and whether a formal environmental impact statement is required; and to aid an agency's compliance with the National Environmental Policy Act when no environmental impact statement is necessary.

Environmental impact -- The positive or negative effect of any action upon a give area or resource.

Environmental impact statement -- A formal document to be filed with the Environmental Protection Agency that considers significant environmental impacts expected from implementation of a major federal action.

Ephemeral Streams -- Streams which flow only in direct response to precipitation and whose channel is at all times above the water table.

Epilimnion -- The upper region of a thermally stratified lake, above the thermocline, and generally warm and well oxygenated.

Equlibrium Catch -- The catch (in numbers) taken from a fish stock when it is in equilibrium with fishing of a given intensity, and (apart from the effects of environmental variation) its abundance is not changing from one year to the next.

Equlibrium Yield -- The yield in weight taken from a fish stock when it is in equilibrium with fishing of a given intensity, and (apart from effects of environmental variation) its biomass is not changing from one year to the next. Also called; sustainable yield, equivalent sustainable yield.

Erosion -- Wearing away of rock or soil by the gradual detachment of soil or rock fragments by water, wind, ice, and other mechanical, chemical, or biological forces.

ESA -- The U.S. Endangered Species Act.

Escapement (Spawning) -- The portion of a fish population that survives sources of natural mortality and harvest to reach its natal spawning grounds.

Estuary -- A coastal body of water that is semi-enclosed, openly connected with the ocean, and mixes with freshwater drainage from land.

ESU -- "Evolutionarily Significant Unit; a ""distinct"" population of Pacific salmon, and hence a species, under the Endangered Species Act."

Euryhaline -- Having a wide tolerance to salinity.

Eutrophic -- Usually refers to a nutrient-enriched, highly productive body of water.

Eutrophication -- The process of enrichment of water bodies by nutrients.

Evaporation -- The physical process by which a liquid (or a solid) is transformed to the gaseous state. In Hydrology, evaporation is vaporization that takes place at a temperature below the boiling point.

Even-year pink salmon -- Pink salmon that spawn in even-numbered years. The distribution of these fish is variable, but their abundance tends to increase at higher latitudes in both Asia and North America. Even-year pink salmon spawning regularly south of British Columbia are found only in the Snohomish River, Washington.

Even-year run -- A population of fish that returns to its natural spawning grounds in even numbered years.

Evolutionarily significant unit (ESU) -- "A definition of ""species"" used by NMFS in administering the Endangered Species Act. An ESU is a population (or groups of populations) that (1) is reproductively isolated from other conspecific population units, and (2) represents an important component in the evolutionary legacy of the species."

Exotic species -- Introduced species not native to the place where they are found (e.g., Atlantic salmon to Oregon or Washington).

Exploitation pattern -- The distribution of fishing mortality over the age composition of the fish population, determined by the type of fishing gear, area and seasonal distribution of fishing, and the growth and migration of the fish. The pattern can be changed by modifications to fishing gear, for example, increasing mesh or hook size, or by changing the ratio of harvest by gears exploiting the fish (e.g., gill net, trawl, hook and line, etc.).

Exploitation rate -- The proportion of a population at the beginning of a given time period that is caught during that time period (usually expressed on a yearly basis). For example, if 720,000 fish were caught during the year from a population of 1 million fish alive at the beginning of the year, the annual exploitation rate would be 0.72.

Extinct species -- A species that no longer exists.

Extinction -- The natural or human induced process by which a species, subspecies or population ceases to exist.

Eyed egg -- A fish egg containing an embryo that has developed enough so the eyes are visible through the egg membrane.

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F0.1 -- The fishing mortality rate at which the increase in yield-per-recruit in weight for an increase in a unit-of-effort is only 10 percent of the yield-per-recruit produced by the first unit of effort on the unexploited stock (i.e., the slope of the yield-per-recruit curve for the F0.1 rate is only one-tenth the slope of the curve at its origin).

Falcate -- Hooked or curved like a sickle.

Fall-run fish -- Anadromous fish that return to spawn in the fall.

Fauna -- (1) A term used to describe the animal species of a specific region or time. (2) All animal life associated with a given habitat, country, area, or period.

Fecundity -- The total number of eggs produced by a female fish.

Federal Energy Regulatory Commission (FERC) -- The Commission issues and regulates licenses for construction and operation of non federal hydroelectric projects and advises federal agencies on the merits of proposed federal multipurpose water development projects.

Federal land managers -- This category includes the Bureau of Indian Affairs; the Bureau of Land Management; the National Park Service, all part of the U.S. Department of the Interior; and the Forest Service, U.S. Department of Agriculture.

Federal project operators and regulators -- Federal agencies that operate or regulate hydroelectric projects in the Columbia River Basin. They include the Bonneville Power Administration, the Bureau of Indian Affairs, the Bureau of Reclamation, the Corps of Engineers and the Federal Energy Regulatory Commission.

FELCC -- Firm energy load carrying capability (FELCC) is the amount of energy the region's generating system, or an individual utility or project, can be called on to produce on a firm basis during actual operations. FELCC is made up of both hydro and non-hydro resources, including power purchases.

Fill -- (Geology) Any sediment deposited by any agent such as water so as to fill or partly fill a channel, valley, sink, or other depression.

Fill Dam -- Any dam constructed of excavated natural materials or of industrial waste materials.

Fin Ray -- A soft or hard cartilaginous rod in fins.

Final environmental impact statement (FEIS) -- The final report of environmental effects of proposed action on an area of land. This is required for major federal actions under Section 102 of the National Environmental Policy Act. It is a revision of the draft environmental impact statement to include public and agency responses to the draft.

Fingerling -- Refers to a young fish in its first or second year of life.

Firm energy -- the amount of energy that can be generated given the region's worst historical water conditions. It is energy produced on a guaranteed basis.

Fish and wildlife agencies -- This category includes the Fish and Wildlife Service, U.S. Department of the Interior; the Idaho Department of Fish and Game; the Montana Department of Fish, Wildlife and Parks; the National Marine Fisheries Service, U.S. Department of Commerce; the Oregon Department of Fish and Wildlife; and the Washington Department of Fish and Wildlife.

Fish flows -- "Artificially increased flows in the river system called for in the fish and wildlife program to quickly move the young fish down the river during their spring migration period. (See ""water budget."")"

Fish guidance efficiency (FGE) -- The proportion of juvenile fish passing into the turbine intakes that are diverted away from the turbines and into bypass facilities.

Fish ladder -- See Fishway.

Fish Passage Center -- Part of the water budget program, the center plans and implements the annual smolt monitoring program; develops and implements flow and spill requests; and monitors and analyzes research results to assist in implementing the water budget. (See water budget.)

Fish passage efficiency (FPE) -- The proportion of juvenile fish passing a project through the spillway, sluiceway, or juvenile bypass system, as opposed to passing through the turbines.

Fish passage facilities -- Features of a dam that enable fish to move around, through, or over without harm. Generally an upstream fish ladder or a downstream bypass system.

Fish passage managers -- Located at the Fish Passage Center, the two fish passage managers are responsible for the specific planning, implementation and monitoring activities of the Center aimed at helping fish on their migratory routes in the Columbia River Basin. One manager is designated by a majority of the federal and state fish and wildlife agencies, and the other manager is designated by a majority of the Columbia River Basin Indian tribes. (See Fish Passage Center.)

Fish screen -- A screen across the turbine intake of a dam, designed to divert the fish into the bypass system.

Fishery -- The act, process, or occupation of attempting to catch fish, which may be retained or released.

Fishing Effort -- 1. The total fishing gear in use for a specified period of time. When two or more kinds of gear are used, they must be adjusted to some standard type 2. Effective fishing effort.

Fishing Intensity -- 1. Effective fishing effort. 2. Fishing effort per unit area 3. Effectiveness of fishing.

Fishing Mortality -- Deaths in a fish stock caused by fishing.

Fishing Power -- The catch which a particular gear or vessel takes from a given density of fish during a certain time interval. For example, larger vessels (horsepower) have a greater ability to catch more fish, thus the greater their fishing power. Also, improvements in a vessel or gear, such as fish finders, Loran, etc., can increase fishing power.

Fishway -- A device made up of a series of stepped pools, similar to a staircase, that enables adult fish to migrate up the river past dams.

Fitness -- The relative ability of an individual (or population) to survive and reproduce (pass on it's genes to the next generation) in a given environment.

Fixed drawdown period -- The late summer and fall when the volume of the next spring runoff is not yet known, and reservoir operations are guided by fixed rule curve based on historical streamflow patterns.

Flash Flood -- A sudden flood of great volume, usually caused by a heavy rain. Also, a flood that crests in a short length of time and is often characterized by high velocity flows. It is often the result of heavy rainfall in a localized area.

Floodplain -- Land that gets covered with water as a result of the flooding of a nearby stream. Or level lowland bordering a stream or river onto which the flow spreads at flood stage.

Floodplain (100-year) -- The area adjacent to a stream that is on average inundated once a century.

Flora -- (1) A term used to describe the entire plant species of a specified region or time. (2) The sum total of the kinds of plants in an area at one time. All plant life associated with a given habitat, country, area, or period. Bacteria are considered flora.

Flow -- The amount of water passing a particular point in a stream or river, usually expressed in cubic-feet per second (cfs).

Flow augmentation -- Increased flow from release of water from storage dams.

Flume -- (1) A narrow gorge, usually with a stream flowing through it. (2) An open artificial channel or chute carrying a stream of water, as for furnishing power, conveying logs, or as a measuring device.

Fluvial -- Migrating between main rivers and tributaries. Of or pertaining to streams or rivers.

Fmax -- The rate of fishing mortality for a given exploitation pattern rate of growth and natural mortality, that results in the maximum level of yield-per-recruit. This is the point that defines growth overfishing.

Fontanelle -- Unossified gap between cranial bones.

Food chain -- Organisms that are interrelated in their feeding habits, each feeding upon organisms that are lower in the chain and in turn being fed on by organisms higher in the chain.

Forage Fish -- Small fish which breed prolifically and serve as food for predatory fish.

Ford -- A shallow place in a body of water, such as a river, where one can cross by walking or riding on an animal or in a vehicle.

Forebay -- The part of a dam's reservoir that is immediately upstream from the powerhouse.

Forebay guidance net -- A large net placed in the forebay of a dam to guide juvenile fish away from the powerhouse.

Forest canopy -- The cover of branches and foliage formed collectively by the crowns of adjacent trees and other woody growth.

Forest fragmentation -- The change in the forest landscape, from extensive and continuous forests of old-growth to mosaic of younger stand conditions.

Forest land -- Land that is now, or is capable of becoming, at least 10 percent stocked with forest trees and that has not been developed for nontimber use.

Forest landscape -- Land presently forested or formerly forested and not currently developed for nonforest use.

Fragmentation -- The process of reducing size and connectivity of stands that compose a forest.

Frenum -- Referring to the membrane that binds the lip to the snout or lower jaw.

Freshet -- A rapid temporary increase in stream flow due to heavy rains or snow melt.

Freshwater marsh -- Open wetlands that occur along rivers and lakes.

Freshwater swamp -- Forested or shrubby wetlands.

Fry -- A stage of development in young salmon or trout. During this stage the fry is usually less than one year old, has absorbed its yolk sac, is rearing in the stream, and is between the alevin and parr stage of development.

Full pool -- The maximum level of a reservoir under its established normal operating range.

Full-sib family -- A group of individuals that shares the same two parents (i.e., brothers and sisters). Members of a half-sib family, by contrast, share only one parent.

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Gabion -- A wire basket or cage that is filled with gravel and generally used to stabilize stream banks and improve degraded aquatic habitat.

Gaging station -- A particular site in a stream, lake, reservoir, etc., where hydrologic data are obtained.

Gallery -- "(1) A passageway within the body of a dam or abutment; hence the terms ""grouting gallery,"" ""inspection gallery,"" and ""drainage gallery."" (2) A long and rather narrow hall; hence the following terms for a power plant: ""valve gallery,"" ""transformer gallery,"" and ""busbar gallery."""

Gallons per minute (Gpm) -- A unit used to measure water flow.

Game fish -- A fish that is regulated by law for recreational harvest.

Gametes -- The sexual reproductive cells, eggs and sperm.

Gap Analysis -- A method for determining spatial relationships between areas of high biological diversity and the boundaries of National Parks, National Wildlife Refuges (NWR), and other preserves.

Gape -- To open the mouth wide. In Zoological terms, it means the measurement of the widest possible opening of a mouth.

Gas Supersaturation -- The overabundance of gases in turbulent water, such as at the base of a dam spillway. Can cause fatal condition in fish similar to the bends.

Gene -- The chemical unit of hereditary information that can be passed on from generation to generation.

Gene diversity analysis -- A hierarchical analysis of the genetic variation observed at polymorphic loci (see allele) in a set of samples that partitions this variation into several, typically geographic, components. Diversity analysis commonly estimates the proportions of observed variation expressed 1) among areas or regions, 2) among populations within areas, and 3) within populations. The total of these proportions equals 1.

Gene locus -- The site on a chromosome where a gene is found.

Gene pool -- The total genes in a breeding population.

Gene-2 -- The basic unit of heredity passed from parent to offspring.

Generation -- Act or process of producing electric energy from other forms of energy. Also refers to the amount of electric energy so produced.

Generator -- A machine that changes water power, steam power, or other kinds of mechanical energy into electricity.

Genetic conservation -- The preservation of genetic resources in breeding populations.

Genetic conservation refuge -- Reserve area whose goal is to protect genetic diversity and natural evolutionary processes within and among natural populations, while allowing varying degrees of exploitation and modification.

Genetic distance -- A quantitative measure of genetic differences between a pair of samples.

Genetic diversity -- The array of genetic traits that exists within a population which enables it to adapt to changing conditions.

Genetic drift -- The random fluctuation of allele frequencies in a population resulting from the sampling of gametes to produce a finite number of individuals in the next generation.

Genetic integrity -- The ability of a breeding population or group of breeding populations to remain adapted to its natural environment.

Genetic introgression -- The entry or introduction of a gene from one gene complex into another, as in introgressive hybridization, which is the spread of genes of one species into the gene complex of another as a result of hybridization between numerically dissimilar populations in which extensive backcrossing prevents formation of a single stable population.

Genetic risk -- The probability of an action or inaction having a negative impact of the genetic character of a population or species.

Genetic stock identification (GSI) -- A method that can be used to characterize populations of organisms based on the genetic profiles of individuals.

Genetics -- The study of genes and gene pools.

Genotype -- The complement of genes in an individual. Or the entire genetic constitution of an organism.

Geographic information system (GIS) -- A computer system capable of storing and manipulating spatial (i.e., mapped) data.

Gill rakers -- A series of projections located along the front edge of the gill arch.

Gill-net fishery -- Any fishery where the gear is limited to the use of gill nets only. A gill net is designed to catch a fish by allowing it to insert its head into a net mesh far enough that the mesh will slip over the gill flaps or opercles. When this happens the fish is gilled or becomes trapped.

Gills -- The fleshy, and highly vascular organs comparable to lungs used in aquatic respiration.

Glide -- A section of stream that has little or no turbulence.

Gradient -- Vertical drop per unit of horizontal distance.

Grass/Forb -- An early forest successional stage where grasses and forbs are the dominant vegetation.

Gravel -- See cobble.

Gravity Dam -- A dam constructed of concrete and/or masonry that relies on its weight for stability.

Gravity feed system -- A system that provides flow in a channel or conduit through the use of gravity.

Gray Water -- Waste water from a household or small commercial establishment which specifically excludes water from a toilet, kitchen sink, dishwasher, or water used for washing diapers.

Grilse -- Salmon less than 22 inches (56cm) Fork Length (FL).

Groundwater -- Subsurface water and underground streams that can be collected with wells, or that flow naturally to the earth's surface though springs.

Growth overfishing -- The rate of fishing, as indicated by an equilibrium yield-per-recruit curve, greater than which the losses in weight from total mortality exceed the gain in weight due to growth. This point is defined as Fmax.

Guideline -- Administrative constraints applicalbe in developing a plan and criteria directing the actions taken to achieve objectives.

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Habitat -- The local environment in which a organism normally lives and grows.

Habitat conservation plan (HCP) -- An agreement between the Secretary of the Interior and either a private entity or a state that specifies conservation measures that will be implemented in exchange for a permit that would allow taking of a threatened or endangered species.

Habitat diversity -- The number of different types of habitat within a given area.

Habitat fragmentation -- The breaking up of habitat into discrete islands through modification or conversion of habitat by management activities.

Half-pounder -- A life history trait of steelhead exhibited in the Rogue, Klamath, Mad, and Eel Rivers of southern Oregon and northern California. Following smoltification, half-pounders spend only 2-4 months in the ocean, then return to fresh water. They overwinter in fresh water and emigrate to salt water again the following spring. This is often termed a false spawning migration, as few half-pounders are sexually mature.

Harvest -- Fish that are caught and retained in a fishery (consumptive harvest).

Harvest controls -- Regulations established for commercial and sport fisheries to ensure that the correct proportion of the different stocks escape to spawn.

Harvest management -- The process of setting regulations for the commercial, recreational and tribal fish harvest to achieve a specified goal within the fishery.

Harvest rate -- The proportion of a returning run or total population of salmonids that is taken by fisheries, usually expressed as a catch to escapement ratio.

Hatch box -- A device used to incubate relatively small numbers of fish eggs. The hatch box is usually located adjacent to a stream, which supplies the box with water.

Hatchery -- Refers to facilities that incubate eggs and rear the young for release into streams and rivers.

Hatchery production -- The spawning, incubation, hatching, or rearing of fish in a hatchery or other artificial production facility.

Hatchery rack -- A weir or trap where returning adult fish are intercepted for hatchery or other use.

Hatchery stock -- A stock that depends upon spawning, incubation, hatching, or rearing in a hatchery or other artificial production facility.

Hazardous materials -- Anything that poses a substantive present or potential hazard to human health or the environment when improperly treated, stored, transported, disposed of, or otherwise managed.

Headgate -- The gate that controls water flow into irrigation canals and ditches. A watermaster regulates the headgates during water distribution and posts headgate notices declaring official regulations.

Headwater -- Referring to the source of a stream or river

Headworks -- A flow control structure on an irrigation canal.

Healthy stock -- A stock of fish experiencing production levels consistent with its available habitat and within the natural variations in survival for the stock.

Heavy metals -- Metallic elements with high atomic weights, e.g., mercury, chromium, cadmium, arsenic, and lead. They can damage living things at low concentrations and tend to accumulate in the food chain.

Herbaceous -- Vegetation or parts of plants with little or no woody tissue.

Heterocercal -- Said of the tail when the vertebrae curve upward into the upper lobe of the caudal fin.

Home range -- The area that an animal traverses in the scope of normal activities. This is not to be confused with territory, which is the area an animal defends.

Homing -- The ability of a salmon or steelhead to correctly identify and return to their natal stream, following maturation at sea.

Horizontal distribution -- The location of fish in the cross section of a river or a lake.

Husbandry -- The scientific management and control of the hatchery environment for the production of fish or wildlife.

Hybrid -- An offspring that results from the mating of individuals of different races or species.

Hybridization -- The crossing or mating of two different varieties of plants or animals.

Hydraulic head -- The vertical distance between the surface of the reservoir and the surface of the river immediately downstream from the dam.

Hydric -- Wet.

Hydroelectricity (Hydroelectric power) -- The production of electric power through use of the gravitational force of falling water.

Hydrologic unit -- A distinct watershed or river basin defined by an 8-digit code.

Hydrology -- The scientific study of the water of the earth, its occurrence, circulation and distribution, its chemical and physical properties, and its interaction with its environment, including its relationship to living things.

Hydropower system -- The hydroelectric dams on the Columbia River and its tributaries.

Hypolimnion -- The lower zone of a thermally stratified lake, below the thermocline, and usually depleted in oxygen during summer stagnation.

Hyporheic zone -- The area under the stream channel and floodplain that contributes to the stream.

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Ichthyology -- The scientific study of fishes.

IHN -- Infectious Hematopoietic Necrosis; a viral disease endemic to salmonid fishes of the Pacific Coast of North America that can cause high mortality in 3-week to 6-month-old fish.

Imbricated -- Lying lapped over each other in regular order (like scales of a fish or shingles on a roof).

Immigration -- Referring to the movement of organisms into an area. See emigration and migrating.

Impact -- A spatial or temporal change in the environment caused by human activity.

Impoundment -- A body of water formed behind a dam.

Imprinting -- The physiological and behavioral process by which migratory fish assimilate environmental cues to aid their return to their stream of origin as adults.

In-lieu energy -- Energy provided by a reservoir owner instead of water to which a downstream party is entitled.

In-situ -- In place. An in-situ environmental measurement is one that is taken in the filed, without removal of a sample to the laboratory.

Inbreeding -- Mating or crossing of individuals more closely related that average pairs in the population.

Inbreeding depression -- A reduction in fitness resulting from mating between close relatives that occurs by chance in small populations or by assortative mating in large populations.

Incidental harvest -- The take (or harvest) of species other than the target species in a fishery.

Incidental take -- """Take"" of a threatened or endangered species that is incidental to, and not the purpose of, the carrying out of an otherwise lawful activity."

Incised River -- A river which cuts its channel through the bed of the valley floor, as opposed to one flowing on a floodplain; its channel formed by the process of degradation.

Incubation -- The period of time from egg fertilization until hatching.

Incubation channel -- A man-made channel in the streambed used for hatching fish eggs.

Indicator (Organism) -- (Water Quality) An organism, species, or community that shows the presence of certain environmental conditions.

Indigenous -- Existing naturally in a region, state, country, etc.

Infauna -- Aquatic animals that live in the substrate of a body of water, especially in a soft sea bottom.

Inferior mouth -- The type of mouth that opens on the ventral surface (like sturgeon).

Infiltration (soil) -- The movement of water through the soil surface into the soil.

Inflow -- Water that flows into a reservoir or forebay during a specified period.

Instantaneous flows -- The velocity of a volume of water.

Instantaneous Rate Of Fishing Mortality -- When fishing and natural mortality act concurrently, F is equal to the instantaneous total mortality rate, multiplied by the ratio of fishing deaths to all deaths. Also called; rate of fishing; instan- taneous rate of fishing; *force of fishing mortality .

Instantaneous Rate Of Growth -- The natural logarithm of the ratio of final weigl1t to initial weight of a fish in a unit of time, usually a year. When applied collectively to all fish of a given age in a stock, the possibility of selective morta lity must be considered .

Instantaneous Rate Of Mortality -- The natural logarithm (with sign changed) of the survival rate. The ratio of number of deaths per unit of time to population abundance during that time, if all deceased fish were to be immediately replaced so that population does not change. Also called; *coefficient of decrease.

Instantaneous Rate Of Natural Mortality -- When natural and fishing mortality operate concurrently it is equal to the instantaneous total mortality rate, multi- plied by the ratio of natural deaths to all deaths. Also called; *force of natural mortality .

Instantaneous Rate Of Recruitment -- "Number of fish that grow to catchable size per short interval of time, divided by the number of catchable fish already present at that time. Usually given on a yearly basis; that is, the figure just described is divided by the fraction of a year represented by the ""short interval"" in question. This concept is used principally when the size of the vulnerable stock is not changing or is changing only slowly, since among fishes recruitment is not usually associated with stock size in the direct way in which mortality and growth are."

Instantaneous Rate Of Surplus Production -- "Equal to rate of growth plus rate of recruitment less rate of natural mortality--all in terms of weight and on an instantaneous basis. In a ""balanced"" or equilibrium fishery, this increment replaces what is removed by fishing, and rate of surplus production is numerically equal to rate of fishing. Also called; *instantaneous rate of natural increase."

Instream cover -- The layers of vegetation, like trees, shrubs, and overhanging vegetation, that are in the stream or immediately adjacent to the wetted channel.

Instream flow work group -- An interagency group that simulated the effects of various fish flow regimes by using hydropower regulation computer models. The group was composed of technical experts and water resource managers from the fish and wildlife agencies, federal dam operators and regulators, and state water management agencies.

Instream flows -- See flows.

Intake -- The entrance to a turbine at a dam, diversion works, or pumping station.

Intake traveling screens -- See turbine intake screens.

Interim (short-term) solution -- Actions to be taken in a 2- to 4-year period.

Interim spill -- The spilling of water over John Day, The Dalles, Bonneville, Lower Monumental and Ice Harbor dams to aid fish passage. This method will be used until permanent solutions to juvenile fish passage problems are developed.

Intermittent stream -- Any nonpermanent flowing drainage feature having a definable channel and evidence of scour or deposition. This includes what are sometimes referred to as ephemeral streams if they meet these two criteria.

Interorbital -- The space between the eyes.

Interspecific -- Occurring among members of different species.

Interspecific competition -- The condition of rivalry that exists when a number of organisms of different species use common resources.

Intraspecific -- Occurring among members of a single species.

Introgression -- Introduction of genes from one population or species into another.

Invertebrate drift -- Stream and terrestrial invertebrates that float with the current.

Irrigation diversion -- Generally, a ditch or channel that deflects water from a stream channel for irrigation purposes.

Island model of migration -- An equilibrium model of gene flow and genetic drift that is applied under the assumption that a species (or operational taxonomic unit or ESU) is subdivided into populations of equal size, all of which exchange migrants at a constant rate, with migrants coming with equal probability from all other populations.

Isolate -- A population that is isolated.

Isolation -- Absence of genetic crossing among populations because of distance or geographic barriers.

Issue -- A matter of controversy or dispute over resource management activities that is well defined or topically discrete.

Iteroparous -- Species that reproduce repeatedly during their lifetime.

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Jack salmon -- A young male salmon that matures precociously(earlier than other fish in its age-class).

Jacks -- Male salmon that return from the ocean to spawn one or more years before full-sized adults return. For coho salmon in California, Oregon, Washington, and southern British Columbia, jacks are 2 years old, having spent only 6 months in the ocean, in contrast to adults, which are 3 years old after spending 1« years in the ocean.

Jennie salmon -- A young female salmon that matures precociously(earlier than other fish in its age-class).

Jeopardy -- A finding made through consultation under the Endangered Species Act that the action of a federal agency is likely to jeopardize the continued existence of a threatened or endangered species.

Jills -- "Female salmon that return from the ocean to spawn one or more years before full-sized adults return. For sockeye salmon in Oregon, Washington, and southern British Columbia, jills are 3 years old (age 1.1), having spent only one winter in the ocean, in contrast to more typical sockeye salmon that are age 1.2,1.3, 2.2 or 2.3 on return."

Jugular pelvics -- Pelvic fins in front of the pectoral fins.

Juvenile -- Fish from one year of age until sexual maturity.

Juvenile transportation -- Collecting migrating juvenile fish and transporting them around the dams using barges or trucks.

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KAF -- A thousand acre feet, same as .504 thousand second foot days.

Karyotype -- The number, size, and morphology of the chromosome complement.

KCFS -- A measurement of water flow equivalent to 1,000 cubic feet of water passing a given point for an entire second.

Kcfs-month -- One kcfs-month is a flow of 1,000 cubic feet per second for one month or 0.0595 million acre-feet.

Kelt -- A spent or spawned out steelhead salmon.

Key watershed -- As defined by National Forest and Bureau of Land Management District fish biologists, a watershed containing (1) habitat for potentially threatened species or stocks of anadromous salmonids or other potentially threatened fish, or (2) greater than 6 square miles with high-quality water and fish habitat.

Kilowatt (KW) -- The electrical unit of power which equals 1,000 watts or 1.341 horsepower.

Kilowatt-hour (kWh) -- A basic unit of electrical energy that equals one kilowatt of power applied for one hour.

Known-stock fishery -- A fishery taking place in an area and during a time where only fish of a certain stock are present.

Kokanee -- The self-perpetuating, nonanadromous form of O. nerka that occurs in balanced sex-ratio populations and whose parents, for several generations back, have spent their whole lives in fresh-water.

Krill -- Small abundant crustaceans that form an important part of the food chain in Antarctic waters.

KSFD -- A volume of water equal to 1,000 cubic feet of water flowing past a point for an entire day. Same as 1.98 FAF.

Kype -- The distinctive hooked jaw that male salmon develop during spawning.

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Landing -- Any place on or adjacent to the logging site where logs are assembled for further transport.

Landscape -- A heterogenous land area with interacting ecosystems that are repeated in similar form throughout.

Landscape diversity -- The size, shape, and connectivity of different ecosystems across a large area.

Landscape features -- The land and water form vegetation, and structures that compose the characteristic landscape.

Landslide -- A movement of earth down a steep slope.

Large woody debris -- Pieces of wood larger than 10 feet long and 6 inches in diameter, in a stream channel.

Late seral state forest -- Stage in forest development that includes mature and old-growth forest.

Lateral line -- A series of sensory pores opening to the exterior along the side of fish.

Leave strips -- Generally narrow bands of forest trees that are left along streams and rivers to buffer aquatic habitats from upslope forest management activities.

Length Frequency -- An arrangement of recorded lengths which indicates the number of times each length or length interval occurs.

Lentic -- Characterizing aquatic communities found in standing water.

Levee -- An embankment constructed to prevent a river from overflowing (flooding).

Limiting factor -- "A requirement such a food, cover or spawning gravel that is in shortest supply with respect to all resources necessary to sustain life and thus ""limits"" the size or retards production of a fish population."

Limnetic -- Referring to a standing water Ecosystem (ponds or lakes).

Limnology -- The study of lakes, ponds and streams.

Litter layer -- The loose, relatively undecomposed organic debris on the surface of the forest floor made up typically of leaves, bark, small branches, and other fallen material.

Littoral zone -- The region of land bordering a body of water.

Live box -- A container filled with water and often equipped with accessories such as aeration equipment that is used to hold and transport live fish.

Load -- The amount of electric power or energy delivered or required at any specified point or points on a system.

Load shaping -- The adjustment of storage releases so that generation and load are continuously in balance.

Loading -- The influx of pollutants to a selected water body.

Lock -- A chambered structure on a waterway closed off with gates for the purpose of raising or lowering the water level within the lock chamber so ships, boats, and tugs/barges can move from one elevation to another along the waterway.

Locus (pl. loci) -- The site on a chromosome where a gene is found. The term locus is often used more or less synonymously with gene.

Long-term potential catch -- The largest annual harvest in weight that could be removed from a fish stock year after year, under existing environmental conditions. This can be estimated in various ways, from maximum values from production models to average observed catches over a suitable period of years.

Lotic -- Meaning or regarding things in running water.

Low-head dam -- A dam at which the water in the reservoir is not high above the turbine units.

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Macroinvertebrate -- Invertebrates visible to the naked eye, such as insect larvae and crayfish.

Macrophytes -- Aquatic plants that are large enough to be seen with the naked eye.

MAF -- Million acre feet. The equivalent volume of water that will cover an area of one million acres to a depth of one foot. One MAF equals 1,000 KAF.

Mainstem -- The principle channel of a drainage system into which other smaller streams or rivers flow.

Mainstem passage -- The movement of salmon and steelhead around or through the dams and reservoirs in the Columbia and Snake rivers.

Mainstem survival -- The proportion of anadromous fish that survive passage through the dams and reservoirs while migrating in the Columbia and Snake rivers.

Maintainable Yield -- """The largest catch that can be maintained from the population, at whatever level of stock size, over an indefinite period. It will be identical to the sustainable yield for populations below the level giving the MSY, and equal to the MSY for populations at or above this level""."

Managed forest -- Any forestland that is treated with silvicultural practices and/or harvested.

Mandibular -- Pertaining to the lower jaw.

Mark-recapture study -- A study that estimates population size by marking a segment of the population at one time and later measuring the ratio of marked animals to total animals.

Masonry Dam -- A dam constructed mainly of stone, brick, or concrete blocks that may or may not be joined with mortar. A dam having only a masonry facing should not be referred to as a masonry dam.

Mass marking -- The marking of all individuals in a population of fish so that individuals can be identified in subsequent life history stages.

Mass movement -- The downslope movement of earth caused by gravity. Includes but is not limited to landslides, rock falls, debris avalanches, and creep. It does not however, include surface erosion by running water. It may be caused by natural erosional processes, or by natural disturbances (e.g., earthquakes or fire events) or human disturbances (e.g., mining or road construction).

Maxillae or maxillaries -- The upper jaw, the upper jaw bones.

Maximum Sustainable Yield -- The largest average catch or yield that can continuously be taken from a stock under existing environmental conditions. (For species with fluctuating recruitment, the maximum might be obtained by taking fewer fish in some years than in others.) Also called; maximum equilibrium catch ; maximum sustained yield; sustainable catch.

Mean Seal Level (MSL) -- A measure of elevation above sea level.

Mechanical bypass systems -- See bypass system.

Megawatt-hour (MWh) -- A unit of electrical energy equal to one megawatt or power applied for one hour.

Megawatts (MW) -- A megawatt is one million watts or one thousand kilowatts, a measure of electrical power or generating capacity. A megawatt will typically serve about 1,000 people. The Dalles Dam produces an average of about 1,000 megawatts.

Mental -- Pertaining to the chin or mentum.

Mesic -- Moderately wet.

Meta-population -- A population comprising local populations that are linked by migrants, allowing for recolonization of unoccupied habitat patches after local extinction events.

Mid-Columbia -- The section of the Columbia River between the junction with the Snake River and Chief Joseph Dam.

Mid-Columbia Coordinating Committee -- A committee whose primary purpose is to improve fish passage at the mid-Columbia dams. It determines annual operating requirements for fish passage at the dams; schedules research projects; and implements flow and spill requirements of the Mid-Columbia Settlement Agreement. The committee is composed of eight representatives of the fish and wildlife agencies, Indian tribes, the three mid-Columbia Public Utility Districts, and a power purchaser’s representative.

Mid-Columbia dams -- Dams owned by the mid-Columbia Public Utility Districts. They include Wells, Rocky Reach, Rock Island, Wanapum and Priest Rapids dams.

Mid-Columbia Public Utility Districts (PUDs) -- Public Utility District No. 1 of Grant County, Public Utility District No. 2 of Chelan County and Public Utility District No. 1 of Douglas County.

Migrant -- Life stage of anadromous and resident fish species which moves from one locale, habitat or system (river or ocean) to another.

Migrating -- Moving from one area of residence to another.

Milt -- The sperm of fishes.

Minimum flow level -- The level of stream flow sufficient to support fish and other aquatic life; to minimize pollution; or to maintain other instream uses such as recreation and navigation.

Minimum operating pool -- The lowest water level of an impoundment at which navigation locks can still operate.

Minimum spanning tree -- A means of depicting nearest genetic neighbors. The tree is an undirected network of smallest genetic distances between genetic samples superimposed on multidimensional scaling graphs to reveal local distortion (pairs of points which look close together in one dimension, but which are far apart in other dimensions).

Mitchell Act -- The Mitchell Act of 1938 (Public Law No. 75-502, 16 U.S.C. 755), which authorizes federal funds for hatchery construction and operation within the Columbia River Basin.

Mitigating measures -- Modifications of actions that (1) avoid impacts by not taking a certain action of parts of an action; (2) minimize impacts by limiting the degree or magnitude of the action and its implementation; (3) rectify impacts by repairing, rehabilitating, or restoring the affected environment; (4) reduce or eliminate impacts over time by preservation and maintenance operations during the life of the action; or (5) compensate for impacts by replacing or providing substitute resources or environments.

Mitigation -- The act of alleviating or making less severe. Generally refers to efforts to alleviate the impacts of hydropower development to the Columbia Basins salmon and steelhead runs.

Mixed stock -- A stock whose individuals originated from commingled native and non-native parents; or a previously native stock that has undergone substantial genetic alteration.

Mixed-stock fishery -- A harvest management technique by which different species, strains, races or stocks are harvested together.

Monitor -- To systematically and repeatedly measure conditions in order to track changes.

Monophyletic -- Relating to, descended from, or derived from one stock or source.

Morphoedaphic index (MEI) -- The most widely used index of potential fish production in lakes. A metric expression of the MEI is derived by dividing a lake's total dissolved solids (mg/L), or its conductivity, by its mean depth in meters.

Morphology -- The structure, form and appearance of an organism.

Mortality -- The number of fish lost or the rate of loss.

Multidimensional scaling -- A nonmetric ordination technique used to visualize genetic relationships among populations in two or three dimensions. This technique requires that the distances between samples in two- or three-dimensional graphs have monotonic relationships to the original genetic distances between pairs of samples.

Myomeres -- The muscle segments.

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Natal -- Birth place.

Natal stream -- Stream of birth.

Native species -- A species of fish indigenous to a specific state.

Native stock -- An indigenous stock of fish that has not been substantially affected by genetic interactions with non-native stocks or by other factors, and is still present in all or part of its original range.

Natural fish -- A fish that is produced by parents spawning in a stream or lake bed, as opposed to a controlled environment such as a hatchery.

Natural Mortality -- Deaths in a fish stock caused by predation, pollution, senility, etc., but not fishing.

Natural production -- See Naturally spawning populations.

Natural Return Ratio (NRR) -- An estimate of the ratio of naturally produced spawners in one generation to total natural spawners (both naturally and hatchery produced) in the previous generation.

Natural selection -- Differential survival and reproduction among members of a population or species in nature; due to variation in the possession of adaptive genetic traits.

Naturalization -- The process by which introduced fish successfully establish a naturally spawning population.

Naturally spawning populations -- Populations of fish that have completed their entire life cycle in the natural environment without human intervention.

Net Increase (or decrease) -- New body substance elaborated in a stock, less the loss from all forms of mortality.

Net pen -- A fish rearing enclosure used in lakes and marine areas.

Nitrogen Supersaturation -- A condition of water in which the concentration of dissolved nitrogen exceeds the saturation level of water. Excess nitrogen can harm the circulatory system of fish.

Nominal catch -- The sum of the catches that are landed (expressed as live weight or equivalents). Nominal catches do not include unreported discards.

Nongame wildlife -- All wild vertebrate and invertebrate animals not subject to sport hunting.

Nonpoint source pollution -- Pollution that does not originate from a clear or discrete source.

Northwest power act -- The Pacific Northwest Electric Power Planning and Conservation Act of 1980 (16 U.S.C. 839 et seq.), which authorized the creation of the Northwest Power and Conservation Council and directed it to develop this program to protect, mitigate and enhance fish and wildlife, including related spawning grounds and habitat on the Columbia River and its tributaries.

Northwest Power Pool Coordinating Group -- An operating group made up of BPA, the Corps, Reclamation, and public and private generating utilities in the Northwest. One of the group's functions is administering the Pacific Northwest Coordination Agreement.

Nutrient cycling -- Circulation or exchange of elements such as nitrogen and carbon between nonliving and living portions of the environment.

Nutrient depletion -- Detrimental changes on a site in the total amount of nutrients and/or their rates of input, uptake, release, movement, transformation, or export.

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Objective -- A specific statement of planned results to be achieved by a predetermined date. Once achieved, the objectives represent measurable progress toward attainment of the broader goal.

Obligate species -- A plant or animal that occurs only in a narrowly defined habitat such as tree cavity, rock cave, or wet meadow.

Ocean take -- The portion of the total harvest for a species or stock that occurs in marine areas.

Ocean type -- Ocean-type chinook salmon populations primarily emigrate to the ocean as subyearlings, although yearling emigrants do occur in some populations. Once in the ocean, ocean-type chinook salmon tend to migrate along the coastlines rather than move directly offshore. Morphologically, ocean-type chinook salmon have fewer vertebrae (70>) than stream-type chinook salmon (<70). Genetic differences between ocean- and stream-type populations are similar to those observed between coastal and inland steelhead and odd- and even-year pink salmon.

Ocean-maturing -- Steelhead that enter fresh water with well-developed gonads and spawn shortly thereafter; commonly referred to as winter steelhead.

Odd-year pink salmon -- Pink salmon that spawn in odd-numbered years. The distribution of these fish is variable, but their abundance tends to increase at lower latitudes in both Asia and North America. Odd-year pink salmon are common in both southern British Columbia and Washington.

Odd-year run -- A population of fish that returns to its natural spawning grounds in odd numbered years, such as the pink salmon.

Off-channel area -- Any relatively calm portion of a stream outside of the main flow.

Off-site enhancement -- The improvement in conditions for fish or wildlife species away from the site of a hydroelectric project that had detrimental effects on fish and/or wildlife, as part or total compensation for those effects. An example of off

Offpeak hours -- Period of relatively low demand for electrical energy, as specified by the supplier (such as the middle of the night).

Old-growth associated species -- Plant and animal species that exhibit a strong association with old-growth forests.

Old-growth forest -- A forest stand usually at least 180-220 years old with moderate to high canopy closure; a multilayered, multispecies canopy dominated by large overstory trees; high incidence of large trees; some with broken tops and other indicators of old and decaying wood (decadence); numerous large snags; and heavy accumulations of wood, including large logs on the ground.

On-site -- Usually refers to projects or activities designed to address harm caused to fish and wildlife at the site of the harm.

Operating year -- The 12 month period from August 1 through July 31.

Operational plan -- An action plan that generally addresses how the objectives in a specific geographic area will be attained.

Opercle -- Refers to the largest bone in the operculum.

Operculum -- The gill cover.

Optimum Yield -- (OY) The yield from a fishery which provides the greatest overall benefit to the nation with particular reference to food production and recreational opportunities; it is based on MSY as modified by economic, social or ecological factors. Precision and Accuracy Precision is the closeness to each other of repeated measurements of the same quantity or object, while accuracy is closeness of a measured or computed value to its true value.

Oregon Production Index (OPI) -- An annual index to the measurable number of 3-year-old adult coho salmon south of Illwaco, Washington.

Outfall -- The mouth or outlet of a river, stream, lake, drain or sewer.

Outflow -- The water that is released from a project during the specified period.

Outmigration -- The migration of fish down the river system to the ocean.

Outplanting -- Hatchery reared fish released into streams for rearing and maturing away from the hatchery sites.

Overstory -- Trees that provide the uppermost layer of foliage in a forest with more that one roughly horizontal layer of foliage.

Oxbow -- An abandoned meander in a river or stream, caused by neck cutoff. Used to describe the U-shaped bend in the river or the land within such a bend of a river.

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Pacific Northwest Coordination Agreement -- An agreement between federal and non federal owners of hydropower generation on the Columbia River system. It governs the seasonal release of stored water to obtain the maximum usable energy subject to other uses.

Pacific Northwest Utilities Conference Committee (PNUCC) -- A group formed by Pacific Northwest utilities officials in order to coordinate policy on Pacific Northwest power supply issues and activities. PNUCC lacks contractual authority, but it plays a major role in regional power planning through its Policy; Steering; Fish and Wildlife; and Lawyers committees, and the Technical Coordination Group. PNUCC publishes the Northwest Regional Forecast, containing information on regional loads and resources.

Pacific Salmon Treaty -- A treaty signed by the United States and Canada in 1984 that governs the harvest of certain salmon stocks in the commercial fisheries of Alaska, Canada and the western continental United States.

Palatines -- Paired bones in the roof of the mouth, lateral to vomer; may bear teeth.

Papilla -- A small fleshy projection.

Papillose -- Covered with papilla.

Parameter -- "A ""constant"" or numerical description of some property of a population (which may be real or imaginary). Cf. statistic."

Parapatric -- Having some geographic overlapping of distributions with the potential for gene flow between populations. See sympatric and allopatric.

Parasitism -- The act of living in close association with another living organism at that organisms expense.

Parietals -- Pared bones on posterior roof of skull, lateral to supraoccipital.

Parr -- The developmental life stage of salmon and trout between alevin and smolt, when the young have developed parr marks and are actively feeding in fresh water.

Parr marks -- Distinctive vertical bars on the sides of young salmonids.

Passage -- The movement of migratory fish through, around, or over dams, reservoirs and other obstructions in a stream or river.

Passive Integrated Transponder (PIT) tags -- Passive Integrated Transponder tags are used for identifying individual salmon for monitoring and research purposes. This miniaturized tag consists of an integrated microchip that is programmed to include specific fish information. The tag is inserted into the body cavity of the fish and decoded at selected monitoring sites.

Pathogens -- Any agent that causes disease, such as a virus, protozoan, bacterium or fungus.

Peak flow -- Refers to a specific period of time when the discharge of a stream or river is at its highest point.

Peak load -- The maximum electrical demand in a stated period of time.

Peat -- Partially decomposed plants and other organic material that build up in poorly drained wetland habitats.

Pectoral fins -- The anterior(front) paired fins, attached to pectoral (shoulder) girdle.

Pelagic -- Of or in the open ocean or open water.

Pelvic fins -- Posterior paired fins, located in the abdominal position or towards the rear.

Perennial streams -- Streams which flow continuously.

Peritoneum -- Membrane lining the body cavity.

pH -- "The negative logarithm of the molar concentration of hydrogen ion. Or a more simple definition of pH is ""acidity."""

Pharyngeal teeth -- Teeth located behind the gills and before the esophagus, and anchored in bone.

Phenogram -- A graphical means of depicting genetic relationships among populations in the form of a branching tree (also often referred to as a dendrogram). The phenogram is generated from summary statistics, such as genetic distances or similarities, and shows the results of clustering these populations based on these statistics. A clustering algorithm commonly used to generate phenograms from genetic distances or similarities is the unweighted pair group method with averages (UPGMA).

Phenotype -- The sum total of the observable or measurable characteristics of an organism produced by its genotype interacting with the environment.

Phenotype-2 -- The phenotype is the appearance of an organism resulting from the interaction of the genotype and the environment.

Physiological -- Pertaining to the functions and vital processes of living organisms and the organs within them.

Phytoplankton -- Microscopic floating plants, mainly algae, that live suspended in bodies of water and that drift about because they cannot move by themselves or because they are too small or too weak to swim effectively against a current.

Pieces -- "Individual items, as in the expression ""two dollars a piece"" . Individual fish."

Placoid scale -- Small plate-like scales that have a rough exterior edge found on sharks and related species.

Plankton -- Minute floating forms of microscopic plants and animals in water which cannot get about to any extent under their own power. They form the important beginnings of food chains for larger animals.

Plume -- The area of the Pacific Ocean that is influenced by discharge from the Columbia River, up to 500 miles beyond the mouth of the river.

Pluvial -- Of rain, formed by the action of rain, for example a body of water.

Point Source (PS) -- (1) A stationary or clearly identifiable source of a large individual water or air pollution emission, generally of an industrial nature. (2) Any discernible, confined, or discrete conveyance from which pollutants are or may be discharged, including (but not limited to) pipes, ditches, channels, tunnels, conduits, wells, containers, rolling stock, concentrated animal feeding operations, or vessels. Point source is also legally and more precisely defined in federal regulations. Contrast with Non-Point Source (NPS) Pollution.

Point Source (PS) Pollution -- Pollutants discharged from any identifiable point, including pipes, ditches, channels, sewers, tunnels, and containers of various types. See Non-Point Source (NPS) Pollution.

Policy -- A specific decision or set of decisions with related actions.

Pollutant -- (1) Something that pollutes, especially a waste material that contaminates air, soil, or water. (2) Any solute or cause of change in physical properties that renders water unfit for a given use.

Polymorphic -- Having more than one form (e.g., polymorphic gene loci have more than one allele).

Polymorphic locus -- If different alleles can be detected at a gene locus, the locus is considered to be polymorphic. If all alleles are of the same type, the locus is considered to be monomorphic. Many population genetic analyses are based on the frequency of different alleles at polymorphic loci.

Polyphyletic -- Relating to or characterized by development from more than one ancestral type.

Pond -- A body of water smaller than a lake, often artificially formed.

Pool -- A reach of stream that is characterized by deep low velocity water and a smooth surface.

Pool/riffle ratio -- The ratio of surface area or length of pools to the surface area or length of riffles in a given stream reach; frequently expressed as the relative percentage of each category. Used to describe fish habitat rearing quality.

Population -- A group of individuals of the same species occupying a defined locality during a given time that exhibit reproductive continuity from generation to generation.

Population density -- Number of individuals of a species per unit of area.

Population dynamics -- The aggregate of changes that occur during the life of a population.

Population viability -- Probability that a population will persist for a specified period across its range despite normal fluctuations in population and environmental conditions.

Population vulnerability analysis -- A systematic process for estimating species, location and time specific criteria for persistence of a population.

Potamodromous -- Exhibiting a behavior involving migrations into smaller river tributaries for spawning and rearing. Potamodromous behavior does not involve migrations out of fresh water.

Power peaking -- The generation of electricity to meet maximum instantaneous power requirements; usually refers to daily peaks.

Powerhouse -- A primary part of a hydroelectric dam where the turbines and generators are housed and where power is produced by falling water rotating turbine blades.

Pre-smolt -- A juvenile salmon or steelhead that has not yet reached the physiological state known as a smolt.

Pre-spawning mortality -- Generally refers to non-fishery mortality of adult salmon and steelhead between the time the fish enter the Columbia River and the completion of spawning.

Precocious -- Fish that have matured quickly, or faster than the remaining fish of its age-class.

Predation -- Hunting and killing another animal for food.

Premaxilla -- The paired bones forming the front of the upper jaw.

Preopercle -- The large membrane bone lying in front of and parallel to the opercle.

Preorbital -- The membrane bone lying in front of and below the eye.

Problem -- An obstacle to achieving a goal or objective.

Production -- 1. The total elaboration of new body substance in a stock in a unit of time, irrespective of whether or not it survives to the end of that time. Also called; *net production ; *total production. 2. *Yield.

Production capacity -- The capacity of a water body or production facility to produce fish.

Productivity -- A measure of the capacity of a biological system. Also used as a measure of the efficiency with which a biological system converts energy into growth and production.

Project -- Run-of-river or storage dam and related facilities; also a diversion facility.

Project outflow -- The volume of water per unit of time released from a project.

Pteryhoids -- Bones of the roof of the mouth lying behind and articulating with the palatines.

Public Utility -- A private business organization, subject to government regulation, that provides an essential commodity or service, such as water, electricity, transportation, or communications, to the public.

Public utility district (PUD) -- A government unit established by voters of a district to supply electric or other utility service.

Punchcard -- A card (alternatively called a tag or stamp) used by steelhead and salmon anglers to record catch information; it is returned to management agency after the fishing season.

Pyloric -- Pertaining to that part of the stomach from which the intestine leads.

Pyloric caecum -- A projection in the form of a blind sac attached to the intestine near the posterior end of the stomach.

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Quota -- A number of fish allocated for harvest to a particular fishing group or area.

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Raceway -- A concrete, rectangular fish-rearing unit generally associated with a hatchery.

Radio-telemetry -- Automatic measurement and transmission of data from remote sources via radio to a receiving station for recording and analysis.

Rain Forest -- A tropical woodland that has an annual rainfall of at least 100 inches (254 centimeters) and often much more, typically restricted to certain lowland areas.

Ramus -- A branch; a projecting part.

Range (of a species) -- The area or region over which an organism occurs.

Rapids -- A reach of stream that is characterized by small falls and turbulent high velocity water.

Raptor -- A bird of prey, adapted for seizing and tearing prey.

Rate Of Exploitation -- The fraction, by number, of the fish in a population at a given time, which is caught and killed by man during the year immediately following . The term may also be applied to separate parts of the stock distinguished by size, sex, etc. Also called; *fishing coefficient .

Rate Of Removal -- An inexactly-defined term that can mean either rate of exploitation or rate of fishing--depending on the context .

Rate Of Utilization -- Similar to rate of exploitation, except that only the fish landed are considered. The distinction between catch and landings is important when considerable quantities of fish are discarded at sea.

Ray -- One of the supports of a fin.

Reach -- A section of stream between two defined points.

Rear -- To feed and grow in a natural or artificial environment.

Rearing -- Refers to the amount of time that juvenile fish spend feeding in nursery areas of rivers, lakes, streams and estuaries before migration.

Rearing habitat -- Areas in rivers or streams where juvenile salmon and trout find food and shelter to live and grow.

Rearing pond -- An artificial impoundment in which juvenile salmon and steelhead are raised prior to release into the natural habitat.

Recolonization -- The reestablishment of an organism in a habitat that it previously occupied.

Recovery -- Action that is necessary to reduce or resolve the threats that caused a species to be listed as threatened or endangered.

Recovery/restoration -- The reestablishment of a threatened or endangered species to a self-sustaining level in its natural ecosystem (i.e., to the point where the protective measures of the Endangered Species Act are no longer necessary).

Recreational fishery (or harvest) -- A fishery limited to use of certain gear types (usually rod and reel) where fish can only be used for personal consumption (not sold) or must be released unharmed.

Recreational Rivers -- Rivers or sections of rivers that are readily accessible by road or railroad, that may have some development along their shoreline, and that may have undergone some impoundment or diversion in the past.

Recruit-to-spawner ratio -- Several measures are employed to estimate the productivity of salmon populations. The recruit-to-spawner ratio estimates the number of recruits (fish that are available for harvest in addition to those that escape the fishery to spawn) produced by the previous generation s spawners. The spawner-to-spawner ratio estimates the number of spawners (those fish that reproduced or were expected to reproduce) in one generation produced by the previous generation s spawners. A spawner-to-spawner ratio of 1.0 indicates that, on average, each spawner produced one offspring that survived to spawn; the size of such a population would remain unchanged over that generation.

Recruitment -- The amount of fish added to the exploitable stock each year due to growth and/or migration into the fishing area. For example, the number of fish that grow to become vulnerable to the fishing gear in one year would be the recruitment to the fishable population that year. This term is also used in referring to the number of fish from a year class reaching a certain age. For example, all fish reaching their second year would be age 2 recruits. Recruitment Curve, Reproduction Curve; A graph of the progeny of a spawning at the time they reach a specified age (for example, the age at which half of the brood has become vulnerable to fishing), plotted against the abundance of the stock that produced them.

Recruitment overfishing -- The rate of fishing above which the recruitment to the exploitable stock becomes significantly reduced. This is characterized by a greatly reduced spawning stock, a decreasing proportion of older fish in the catch, and generally very low recruitment year after year.

Recruits -- The total numbers of fish of a specific stock available at a particular stage of their life history.

Redd -- A nest of fish eggs covered with gravel.

Redd Counts -- A spawning female salmon prepares a series of nests, called a redd, in suitable areas of streams by turning onto her side and beating her caudal fin up and down. Primary factors affecting suitability of spawning habitat include the size of rocks in the substrate and stream flow (high enough to provide adequate aeration for the eggs; low enough to prevent erosion of the nest). A completed redd is a shallow depression in the stream bottom with a rim extending to the downstream end. During spawning, the female continuously digs upstream, covering previously deposited eggs with gravel. Most redds occur in predictable areas and are easily identified by an experienced observer by their shape, size, and color (lighter than surrounding areas because silt has been cleaned away). Redd counts are conducted annually in certain heavy use areas of streams called index streams, which are usually surveyed repeatedly through the spawning season. Colored flags are sometimes placed on nearby trees to identify redds so that they will not be counted repetitively. Annual redd counts are used to compare the relative magnitude of spawning activity between years.

Reforestation -- The natural or artificial restocking of an area with forest trees.

Rehabilitation -- Short-term management techniques that restore fish stocks decimated or destroyed by natural or man-made events.

Relative Abundance -- An estimate of actual or absolute abundance; usually stated as some kind of index; for example, as bottom trawl survey stratified mean catch per tow.

Reproduce -- To produce offspring.

Reregulating project -- A dam and reservoir, located downstream from a hydroelectric peaking plant, with sufficient storage capacity to store the widely fluctuating discharges from the peaking plant and to release them in a relatively uniform manner downstream.

Reregulation -- Storing erratic discharges of water from an upstream hydroelectric plant and releasing them uniformly from a downstream plant.

Reservoir -- A body of water collected and stored in an artificial lake behind a dam.

Resident Fish -- Occupying headwater reaches; may disperse locally, but generally considered non-migratory.

Resident fish substitutions -- The enhancement of resident fish to address losses of salmon and steelhead in those areas permanently blocked to anadromous (ocean migrating) fish as a result of hydroelectric dams.

Resident sockeye salmon -- The progeny of anadromous sockeye salmon parents that spend their adult life in freshwater and are observed together with their anadromous siblings on the spawning grounds.

Resident species -- Species of fish which spend their entire lives in freshwater.

Restoration -- The renewing or repairing of a natural system so that its functions and qualities are comparable to its original, unaltered state.

Riffle -- A reach of stream that is characterized by shallow, fast moving water broken by the presence of rocks and boulders.

Rift -- A shallow or rocky place in a stream, forming either a ford or a rapid.

Riparian area -- An area of land and vegetation adjacent to a stream that has a direct effect on the stream. This includes woodlands, vegetation, and floodplains.

Riparian habitat -- The aquatic and terrestrial habitat adjacent to streams, lakes, estuaries, or other waterways.

Riparian vegetation -- The plants that grow rooted in the water table of a nearby wetland area such as a river, stream, reservoir, pond, spring, marsh, bog, meadow, etc.

Ripple -- (1) To form or display little undulations or waves on the surface, as disturbed water does. (2) To flow with such undulations or waves on the surface.

Riprap -- Usually refers to rocks or concrete structures used to stabilize stream or river banks from erosion.

River basin -- See watershed.

River Basin Plan -- A plan for the development of water and related land resources to make the best use of such resources to meet the basin needs and make the greatest long-term contribution to the economic growth and social well-being of the people of the basin and the nation.

River Channels -- Natural or artificial open conduits which continuously or periodically contain moving water, or which forms a connection between two bodies of water.

River Kilometer (RKm) -- Distance, in kilometers, from the mouth of the indicated river. Usually used to identify the location of a physical feature, such as a confluence, dam, or waterfall.

River miles -- Miles from the mouth of a river to a specific destination or, for upstream tributaries, from the confluence with the main river to a specific destination.

River Reach -- Any defined length of a river.

River Stage -- The elevation of the water surface at a specified station above some arbitrary zero datum (level).

Riverine -- Relating to, formed by, or resembling a river including tributaries, streams, brooks, etc.

Riverine habitat -- The aquatic habitat within streams and rivers.

Rock -- See cobble.

Rockfill Dam -- An embankment dam in which more than 50 percent of the total volume is comprised of compacted or dumped pervious natural or crushed rock.

Roe -- The eggs of fishes.

Rolled Fill Dam -- An embankment dam of earth or rock in which the material is placed in layers and compacted by using rollers or rolling equipment.

Rootwad -- The mass of roots associated with a tree adjacent or in a stream that provides refuge and nutrients for fish and other aquatic life.

Rotenone -- A substance derived from the Derris root that is commonly used to kill fish during lake rehabilitation programs.

Rough Fish -- Those species of fish considered to be of either poor fighting quality when taken on tackle or of poor eating quality, such as carp, gar, suckers, etc. Most species in this group are more tolerant of widely fluctuating environmental conditions than Game Fish.

Rule curves -- Water levels, represented graphically as curves, that guide reservoir operations.

Run (in stream or river) -- A reach of stream characterized by fast flowing low turbulence water.

Run (of fish) -- A group of fish of the same species that migrate together up a stream to spawn, usually associated with the seasons, e.g., fall, spring, summer, and winter runs. Members of a run interbreed, and may be genetically distinguishable from other individuals of the same species.

Run-of-river dams -- Hydroelectric generating plants that operate based only on available inflow and a limited amount of short-term storage (daily/weekly pondage).

Runoff -- Water that flows over the ground and reaches a stream as a result of rainfall or snowmelt.

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Salinity -- The concentration of salt in a body of water. The salinity of a saltwater wetland changes whenever freshwater is added when it rains, and each time the saltwater is added or removed when tide rises and falls.

Salmon and Steelhead Conservation and Enhancement Act -- "The Salmon and Steelhead Conservation and Enhancement Act of 1980 (Public Law 96-561, 16 U.S.C. 3301 et seq.), which authorized the establishment of a cooperative program to conserve and enhance the Pacific Northwest’s salmon and steelhead stocks. The law called for the creation of the Salmon and Steelhead Advisory Commission; the development of a comprehensive salmon and steelhead enhancement plan; and a ""buy-back"" program for commercial fishing vessels, licenses and gear."

Salmonid -- Fish of the family Salmonidae, that includs salmon and steelhead.

Salt marsh -- Saltwater wetlands that occur along many coasts.

Salt Water -- Water which contains a relatively high percentage of sodium chloride.

Sample A -- proportion or a segment of a fish stock which is removed for study, and is assumed to be representative of the whole. The greater the effort, in terms of both numbers and magnitude of the samples, the greater the confidence that the information obtained is a true reflection of the status of a stock (level of abundance in terms of numbers or weight, age composition, etc.)

Sand -- Small substrate particles, generally referring to particles less than 2 mm in diameter. Sand is larger than silt and smaller than cobble or rubble.

Scenic Rivers -- Rivers or sections of rivers that are free of impoundments, with shorelines or watersheds still largely primitive, and shorelines largely undeveloped but accessible in places by roads.

Scour -- The erosive action of running water in streams, which excavates and carries away material from the bed and banks. Scour may occur in both earth and solid rock material.

Scute -- An extendal bony plate, usually keeled.

Sea-Run -- Synonymous to anadromous but is usually used only in reference to the anadromous component of species such as O. clarki and O. mykiss that commonly have both an anadromous and non-anadromous life history form.

Secchi Depth -- A relatively crude measurement of the turbidity (cloudiness) of surface water. The depth at which a Secchi Disc (Disk), which is about 10-12 inches in diameter and on which is a black and white pattern, can no longer be seen.

Secchi Disc -- A circular plate, generally about 10-12 inches (25.4-30.5 cm) in diameter, used to measure the transparency or clarity of water by noting the greatest depth at which it can be visually detected. Its primary use is in the study of lakes.

Sediment -- The organic material that is transported and deposited by wind and water.

Sedimentation -- Deposition of sediment.

Selective breeding -- The intentional selection of individual spawners in artificial production programs to produce particular traits in subsequent generations.

Selective fishery -- A fishery that allows the unharmed release of non-target fish stocks/runs.

Self sustaining population -- A population of salmonids that exists in sufficient numbers to maintain its levels through time without supplementation with hatchery fish.

Self-sustaining population -- "A population that perpetuates itself, in the absence of (or despite) human intervention, without chronic decline, in its natural ecosystem. A self-sustaining population maintains itself at a level above the threshold for listing under the Endangered Species Act. In this document, the terms ""self- sustaining"" and ""viable"" are used interchangeably."

Semelparous -- Species that reproduce only once during their lifetime.

Sensitive species -- Those species that (1) have appeared in the Federal Register as proposed for classification and are under consideration for official listing as endangered or threatened species or (2) are on an official state list or (3) are recognized by the U.S. Forest Service or other management agency as needing special management to prevent their being placed on federal or state lists.

Shaping -- The scheduling and operation of generating resources to meet seasonal and hourly load variations.

Silt -- Substrate particles smaller than sand and larger than clay.

Siltation -- The deposition or accumulation of fine soil particles.

Silviculture -- The science and practice of controlling the establishment, composition, and growth of the vegetation of forest stands.

Sinuosity -- The amount of bending, winding and curving in a stream or river.

Slope -- The side of a hill or mountain, the inclined face of a cutting, canal or embankment or an inclination from the horizontal.

Slope stability -- The resistance of a natural or artificial slope or other inclined surface to failure by landsliding (mass movement).

Slough -- A shallow backwater inlet that is commonly exposed at low tide.

Sluiceway -- An open channel inside a dam designed to collect and divert ice and trash in the river (e.g., logs) before they get into the turbine units and cause damage. (On several of the Columbia River dams, ice and trash sluiceways are being used as, or converted into, fish bypass systems.)

Smolt -- Refers to the salmonid or trout developmental life stage between parr and adult, when the juvenile is at least one year old and has adapted to the marine environment.

Smoltification -- Refers to the physiological changes anadromous salmonids and trout undergo in freshwater while migrating toward saltwater that allow them to live in the ocean.

Snag -- Any standing dead, partially dead, or defective (cull) tree at least 10 inches in diameter at breast height and at least 6 feet tall.

Soft Water -- Water that contains low concentrations of metal ions such as calcium and magnesium. This type of water does not precipitate soaps and detergents. Compare to Hard Water.

Southern oscillation index (SOI) -- An oceanographic indicator of environmental conditions that allows for the prediction of global climate events such as El Nino. The difference between the standardized Tahiti Sea Level Pressure (SLP) and the standardized Darwin SLP measurements.

Spawn -- The act of reproduction of fishes. The mixing of the sperm of a male fish and the eggs of a female fish.

Spawner trap -- A barrier erected in a stream or in a fish ladder intended to divert adult salmon or steelhead for holding prior to taking their eggs or sperm for culturing.

Spawner-to-spawner ratio -- Several measures are employed to estimate the productivity of salmon populations. The spawner-to-spawner ratio estimates the number of spawners (those fish that reproduced or were expected to reproduce) in one generation produced by the previous generation s spawners. A spawner-to-spawner ratio of 1.0 indicates that, on average, each spawner produced one offspring that survived to spawn. The recruit-to-spawner ratio estimates the number of recruits (fish that are available for harvest in addition to those that bypass the fishery to spawn) produced by the previous generation s spawners.

Spawning channel -- An artificial gravel-bed area in which flow, depth and velocity are controlled at ideal levels for spawning by a particular species of salmon or steelhead.

Spawning escapement -- The total number of adult fish returning to a hatchery or stream to spawn.

Spawning stock biomass (SSB) -- The total weight of all sexually mature fish in the population. This quantity depends on year class abundance, the exploitation pattern, the rate of growth, fishing and natural mortality rates, the onset of sexual maturity and environmental conditions.

Spawning stock biomass-per-recruit (SSB/R) -- The expected lifetime contribution to the spawning stock biomass for a recruit of a specific age (e.g., per age 2 individual). For a given exploitation pattern, rate of growth, and natural mortality, an expected equilibrium value of SSB/R can be calculated for each level of F. A useful reference point is the level of SSB/R that would be realized if there were no fishing. This is a maximum value for SSB/R, and can be compared to levels of SSB/R generated under different rates of fishing. For example, the maximum SSB/R for Georges Bank haddock is approximately 9 kg for a recruit at age 1.

Spawning surveys -- Spawning surveys utilize counts of redds and fish carcasses to estimate spawner escapement and identify habitat being used by spawning fish. Annual surveys can be used to compare the relative magnitude of spawning activity between years.

Speciation -- The natural process by which new species evolve from existing ones.

Species -- A group of closely related individuals that can interbreed and produce fertile offspring.

Spill -- Releasing water through the spillway rather than through the turbine units.

Spillway -- "The channel or passageway around or over a dam through which excess water is released or ""spilled"" past the dam without going through the turbines. A spillway is a safety valve for a dam and, as such, must be capable of discharging major floods without damaging the dam, while maintaining the reservoir level below some predetermined maximum level."

Spillway crest elevation -- The point at which the reservoir behind a dam is level with the top of the dam's spillway.

Spine -- A single, median supporting element of a fin, usually stiff. Distinguished from a ray in that it is single, median, never branched or jointed.

Standard length -- The straight distance between the tip of the snout and the base of the caudal fin rays.

Standardization -- The procedure of maintaining methods and equipment as constant as possible.

State water management agencies -- State government agencies that regulate water resources. They include the Idaho Department of Water Resources; the Montana Department of Natural Resources and Conservation; the Oregon Water Resources Department; and the Washington Department of Ecology.

Status of exploitation -- An appraisal of exploitation is given for each stock discussed in the Species Synopsis section using the terms unknown, protected, not exploited, underexploited, moderately exploited, fully exploited, and over-exploited. These terms describe the effect of current fishing effort on each stock, and is based on current data and the knowledge of the stocks over time.

Steelhead -- The anadromous form of the species Oncorhynchus mykiss. Anadromous fish spend their early life history in fresh water, then migrate to salt water, where they may spend up to several years before returning to fresh water to spawn. Rainbow trout is the nonanadromous form of Oncorhynchus mykiss.

Stock -- A specific population of fish spawning in a particular stream during a particular season.

Stock A -- part of a fish population usually with a particular migration pattern, specific spawning grounds, and subject to a distinct fishery. A fish stock may be treated as a total or a spawning stock Total stock refers to both juveniles and adults, either in numbers or by weight, while spawning stock refers to the numbers or weight of individuals which are old enough to reproduce.

Stock origin -- The genetic history of a stock.

Stock status -- The current condition of a stock, which may be based on escapement, run size, survival, or fitness level.

Stock transfer -- Transfer of fish from one location to another. This includes any fish originating outside the geographical boundary of an ESU and transferred into it, any fish transferred out of an ESU's range or between areas occupied by different ESUs, or any fish transferred into vacant habitat.

Stone -- Rock fragments larger than 25.4 cm (10 inches) but less than 60.4 cm (24 inches).

Storage -- The volume of water in a reservoir at a given time.

Storage reservoir -- A reservoir in which storage is help over from the annual high water period to the following low water period.

Strategic plan -- A comprehensive long-term plan that identifies goals and objectives, and the problems in meeting them, together with strategies or actions needed to overcome the problems.

Straying -- A natural phenomena of adult spawners not returning to their natal stream, but entering and spawning in some other stream.

Stream -- A general term for a body of flowing water; natural water course containing water at least part of the year. In Hydrology, the term is generally applied to the water flowing in a natural channel as distinct from a canal. More generally, as in the term Stream Gaging, it is applied to the water flowing in any channel, natural or artificial.

Stream Channel -- The bed where a natural stream of water runs or may run; the long narrow depression shaped by the concentrated flow of a stream and covered continuously or periodically by water.

Stream gradient -- A general slope or rate of change in vertical elevation per unit of horizontal distance of the water surface of a flowing stream.

Stream morphology -- The form and structure of streams.

Stream order -- A hydrologic system of stream classification. Each small unbranched tributary is a first order stream. Two first order streams join to make a second order stream. A third order stream has only first and second order tributaries, and so forth.

Stream reach -- An individual first order stream or a segment of another stream that has beginning and ending points at a stream confluence. Reach end points are normally designated where a tributary confluence changes the channel character or order.

Stream type -- Stream-type chinook salmon populations emigrate to the ocean as one- and two-year-old smolts. As juveniles, stream-type fish exhibit behavioral and morphological characteristics consistent with establishing and maintaining territories in freshwater systems (aggressive behavior, and larger, more colorful, fins). Little is known about the oceanic migration patterns of stream-type chinook salmon.

Stream-maturing -- Steelhead that enter fresh water in a sexually immature condition and require several months in fresh water to mature and spawn, commonly referred to as summer steelhead.

Streambank erosion -- The wearing away of streambanks by flowing water.

Streambank stabilization -- Natural geological tendency for a stream to mold its banks to conform with the channel of least resistance to flow. Also the lining of streambanks with riprap, matting, etc., to control erosion.

Streambed -- The channel through which a natural stream of water runs or used to run, as a dry streambed.

Streamflow -- The rate at which water passes a given point in a stream or river, usually expressed in cubic feet per second (cfs).

Streamlet -- A small stream.

Subabdominal pelvic fin -- Said of pelvic fins when placed forward on abdomen but not attached internally to pectoral girdle.

Subadult -- A developmental life stage when fish exhibit most but not all traits of an adult fish.

Subbasin -- Major tributaries to and segments of the Columbia and Snake rivers.

Subbasin planning -- See system planning.

Subdrainage -- A land area (basin) bounded by ridges or similar topographic features, encompassing only part of a watershed, and enclosing on the order of 5,000 acres; smaller than, and part of, a watershed.

Subimpoundment -- An isolated body of water created by a dike within a reservoir or lake.

Submersible traveling screen -- A wire mesh screen that acts like a conveyor belt when installed in the intakes of turbines at dams guiding and transporting juvenile fish into bypass channels.

Subpopulation -- A well-defined set of interacting individuals that compose a proportion of a larger, interbreeding population.

Subspecies -- A population of a species occupying a particular geographic area, or less commonly, a distinct habitat, capable of interbreeding with other populations of the same species.

Substrate -- The composition of a streambed, including either mineral or organic materials.

Subyearling -- A developmental life stage of fish that are less than one year old.

Success (of fishing) -- Catch per unit of effort.

Succession -- A series of dynamic changes by which one group of organisms succeeds another through stages leading to potential natural community or climax.

Superfund list -- A list of the hazardous waste disposal sites most in need of cleanup. The list is updated annually by the U.S. Environmental Protection Agency (EPA) based primarily on how a site scores using the Hazard Ranking System. Also referred to as the National Priorities List (NPL).

Supersaturation -- See dissolved gas concentrations.

Supplementation -- The release and management of artificially propagated fish in streams with the intent to increase or establish wild fish populations while minimizing associated genetic and ecological risks.

Supramaxilla -- A small bone attached to the posterior end of the maxilla, dorsally.

Surface erosion -- The detachment and transport of soil particles by wind, water, or gravity. Or a groups of processes whereby soil materials are removed by running water, waves and currents, moving ice, or wind.

Surface Water -- All waters whose surface is naturally exposed to the atmosphere, for example, rivers, lakes, reservoirs, ponds, streams, impoundments, seas, estuaries, etc., and all springs, wells, or other collectors directly influenced by surface water.

Surplus -- In a fisheries sense, the number of fish in excess of those needed to maintain a population at some level.

Surplus Production -- Production of new weight by a fishable stock, plus recruits added to it, less what is removed by natural mortality. This is usually estimated as the catch in a given year plus the increase in stock size (or less the decrease). Also called; natural increase, sustainable yield, equilibrium catch .

Survival Rate -- Number of fish alive after a specified time interval, divided by the initial number. Usually on a yearly basis.

Suspended sediment -- Sediment suspended in a fluid by the upward components of turbulent currents, moving ice, or wind.

Sustainable yield -- The number or weight of fish in a stock that can be taken by fishing without reducing the stock biomass from year to year, assuming that environmental conditions remain the same.

Sustained harvest -- A harvest volume that can be maintained through time without decline.

Swim-up fry -- A salmonid fry that is swimming in the water column in search for food.

Sympatric -- Occupying the same geographic area. See parapatric and allopatric.

System planning -- A coordinated systemwide approach to planning in which each subbasin in the Columbia system will be evaluated for its potential to produce fish in order to contribute to the goal of the overall system. The planning will emphasize the integration of fish passage, harvest management and production.

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Tac -- Total allowable catch is the total regulated catch from a stock in a given time period, usually a year.

Tailrace -- The canal or channel that carries water away from the dam.

Tailwater -- The water surface immediately downstream from a dam or hydroelectric powerplant.

Take -- Under the Endangered Species Act, take means to harass, harm, pursue, hunt, shoot, wound, kill, trap, capture, or collect an animal, or to attempt to engage in any such conduct.

Targeted fishery -- A harvest strategy designed to catch a specific groups of fish.

Terminal fisheries -- Fisheries near freshwater (usually the mouth of rivers or bays or near a hatchery release site) where the targeted species is returning to spawn.

Terminal mouth -- Said of the location of the mouth when it opens at the end of the head, as in trout.

Territory -- The area that an animal defends, usually during breeding season, against intruders of its own species.

Test fish -- Fish used for research purposes.

Thalweg -- (1) The lowest thread along the axial part of a valley or stream channel. (2) A subsurface, ground-water stream percolating beneath and in the general direction of a surface stream course or valley. (3) The middle, chief, or deepest part of a navigable channel or waterway.

Thermocline -- That layer of water in a lake in which the temperature changes 10C with each meter increase in depth.

Thoracic pelvics -- Said of the pelvic fins when attached immediately below the pectorals and connected internally with the pectoral girdle.

Tidal flats -- Saltwater wetlands that are characterized by mud or sand and daily tidal fluctuations.

Torrent -- (1) A turbulent, swift-flowing stream. (2) A heavy downpour; a deluge.

Toxic Materials -- Any liquid, gaseous, or solid substance or substances in a concentration which, when applied to, discharged to, or deposited in water or another medium may exert a poisonous effect detrimental to people or to the propagation, cultivation, or conservation of animals, or other aquatic life.

Transboundary -- Refers to U.S. and Canadian border, transboundary pollution refers to pollution originating in Canada.

Transferrin -- Transferrin is a serum protein that is characterized by its specific ability to reversibly bind iron and other metal ions and exhibits a high degree of polymorphism.

Transition period -- A period of environmental change during which a population increases or decreased to a new stable equilibrium level.

Trap -- To catch or take in fish from a stream, or a device which does so.

Trap and haul program -- A program to collect fish at a given point, transport them to a different point, and release them.

Travel corridors -- Paths animals use during their migrations.

Treaty Indians -- Indian tribes with treaties with the US Government which guarantee certain fishing rights on and off the reservations.

Treaty tribes -- Any Indian tribe recognized by the United States government, with usual and accustomed fishing grounds, whose fishing rights were reserved under a treaty and have been affirmed by a federal court.

Trend -- (1) A statistical term referring to the direction or rate of increase or decrease in magnitude of the individual members of a time series of data when random fluctuations of individual members are disregarded. (2) A unidirectional increasing or decreasing change in the average value of a variable.

Tributary -- A stream that flows into another stream, river, or lake.

Troll fishery -- A type of commercial salmon fishery taking place in marine waters where gear is limited to multiple lures or baits trolled behind the boat, attached to lines suspended from long poles or outriggers.

Truncate caudal -- Said of the margin of the caudal fin when it is squared off as in some catfish.

Trunk myomeres of lampreys -- The number of body segments between the last gill opening and the cloacal slit.

Tule -- Fall chinook stock native to the Columbia River tributaries.

Turbidity -- "The term ""turbid"" is applied to waters containing suspended matter that interferes with the passage of light through the water or in which visual depth is restricted."

Turbine -- A mechanism in a dam that rotates with the force of water and produces electricity.

Turbine intake screens -- Large screens, which may have moving or non moving parts, designed to be placed in a dam's turbine intake at an angle to deflect juvenile fish from the intakes into a bypass system.

Type N coho -- A coho stock that rears in ocean waters off the mouth of the Columbia River and northward to the northern Washington coast.

Type S coho -- A coho stock that rears in ocean waters off the mouth of the Columbia River and southerly to northern California.

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U.S./Canada Pacific Salmon Treaty -- Signed in 1984 and ratified by Congress in 1985 as the Salmon Treaty Act, this treaty governs the harvest and rebuilding of certain salmon stocks in Alaskan, Canadian and the continental United States.

Uncontracted water -- A volume of water in a storage reservoir that is not assigned for other purposes, such as irrigation.

Undulating -- To move in waves. Referring to the movement of a female fish's tail in a waving motion used to move gravel for the construction of a redd.

Unknown stock -- This description is applied to stocks where there is insufficient information to identify stock origin or stock status with confidence.

Upriver Bright stock (URB) -- A stock of fall chinook destined for the Columbia River and several tributaries upstream from The Dalles Dam. These fish enter the Columbia from early August with the peak of the run at Bonneville Dam in early September.

Upriver stocks -- Salmon and steelhead stocks that spawn in the Columbia River or its tributaries above Bonneville Dam.

Upwelling -- The movement of nutrient rich waters from the bottom of the ocean to the surface.

Urban runoff -- Storm water from city streets and gutters that usually contains a great deal of litter and organic and bacterial wastes into the sewer systems and receiving waters.

Usable Stock -- The number or weight of all fish in a stock that lie within the range of sizes customarily considered usable (or designated so by law). Also called; *standing crop.

Utilized Stock, Utilized Population -- The part, by number, of the fish alive at a given time, which will be caught in future.

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Velocity -- In this concept, the speed of water flowing in a watercourse, such as a river.

Velocity barrier -- A physical structure, such as a barrier dam or floating weir, built in the tailrace of a hydroelectric powerhouse, which blocks the tailrace from further adult salmon or steelhead migration to prevent physical injury or migration delay.

Ventral fins -- See pelvic fins.

Vermiculations -- Irregular lines or impressions like worm tracks.

Viable population -- A population in a state that maintains its vigor and its potential for evolutionary change.

Virtual Population -- Utilized stock.

Virtual population analysis (or cohort analysis) -- An analysis of the catches from a given year class over its life in the fishery. If 10 fish from the 1968 year class were caught each year for 10 successive years from 1970 to 1979 (age 2 to age 11), then 100 fish would have been caught from the 1968 year class during its life in the fishery. Since 10 fish were caught during 1979, then 10 fish must have been alive at the beginning of that year. At the beginning of 1978, there must have been at least 20 fish alive because 10 were caught in 1978 and 10 more were caught in 1979. By working backward year by year, one can be virtually certain that at least 100 fish were alive at the beginning of 1970. A virtual population analysis goes a step further and calculates the number of fish that must have been alive if some fish also died from causes other than fishing.

Viscosity -- A measure of the resistance of a fluid to flow. For liquids, viscosity increases with decreasing temperature.

Vomer -- The most anterior bone of the roof of the mouth; may bear teeth.

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Warmwater fish -- A broad classification on non-salmonid fish that generally have at least one spiny ray, have pelvic and pectoral fins located behind the gills, and are usually suited for water that consistently exceeds 70 degrees F.

Wash -- (1) To carry, erode, remove, or destroy by the action of moving water. To be carried away, removed, or drawn by the action of water. Removal or erosion of soil by the action of moving water. (2) A deposit of recently eroded debris. (3) Low or marshy ground washed by tidal waters. A stretch of shallow water. (4) (Western United States) The dry bed of a stream, articularly a watercourse associated with an alluvial fan, stream, or river channel. Washes are often associated with arid environments and are characterized by large, high energy discharges with high bed-material load transport. Washes are often intermittent and their beds sparsely vegetated. (5) Turbulence in air or water caused by the motion or action of an oar, propeller, jet, or airfoil.

Washout -- (1) Erosion of a relatively soft surface, such as a roadbed, by a sudden gush of water, as from a downpour or floods. (2) A channel produced by such erosion.

Wasteway -- An open ditch or canal that discharges excess irrigation water or power plant effluent into the river channel.

Water banking -- An administrative system for renting surplus water.

Water budget -- A provision of the Columbia River Basin Fish and Wildlife Program that calls for increasing Columbia and Snake River Flows during the spring fish migration with the intent of increasing downstream survival of migrating juvenile salmon and steelhead.

Water Conservation -- The physical control, protection, management, and use of water resources in such a way as to maintain crop, grazing, and forest lands, vegetative cover, wildlife, and wildlife habitat for maximum sustained benefits to people, agriculture, industry, commerce, and other segments of the national economy.

Water Pollution -- Generally, the presence in water of enough harmful or objectionable material to damage the water's quality.

Water quality -- A term used to describe the chemical, physical, and biological characteristics of water, usually in respect to its suitability for a particular purpose.

Water Resources -- The supply of groundwater and surface water in a given area.

Water rights -- "Priority claims to water. In western States, water rights are based on the principle ""first in time, first in right,"" meaning older claims take precedence over newer ones."

Water yield -- The quantity of water derived from a unit area of watershed.

Waterfall -- A sudden, nearly vertical drop in a stream, as it flows over rock.

Watershed -- An area of land thats total surface drainage flows to a single point in a stream.

Watershed management -- The analysis, protection, development, operation or maintenance of the land, vegetation and water resources of a drainage basin for the conservation of all its resources for the benefit of its residents.

Watershed project -- A comprehensive program of structural and nonstructural measures to preserve or restore a water shed to good hydrologic condition. These measures may include detention reservoirs, dikes, channels, contour trenches, terraces, furrows, gully plugs, revegetation, and possibly other practices to reduce flood peaks and sediment production.

Watershed restoration -- Improving current conditions of watersheds to restore degraded fish habitat and provide long-term protection to aquatic and riparian resources.

Watt -- A measure of the rate at which energy is produced, exchanged, or consumed.

Weak stock -- "Listed in the Integrated System Plan's list of stocks of high or highest concern; listed in the American Fisheries Society report as at high or moderate risk of extinction; or stocks the National Marine Fisheries Service has listed. ""Weak stock"" is an evolving concept; the Council does not purport to establish a fixed definition. Nor does the Council imply that any particular change in management is required because of this definition."

Weir (dam) -- A dam in a river to stop and raise the water, for the purpose of conducting it to a mill, forming a fishpond, or the like. When uncontrolled, the weir is termed a fixed-crest weir. Other types of weirs include broad-crested, sharp-crested, drowned, and submerged.

Weir (fish trap) -- Usually a barrier constructed to catch upstream migrating adult fish.

West side forests -- The 11 National Forests in Washington, Oregon, and California that lie partly or wholly west of the Cascade Mountain Range crest. They are the Gifford Pinchot, Mendocino, Mt. Baker-Snowqualmie, Mt. Hood, Olympic, Rouge River, Siskiyou, Siuslaw, Six Rivers, Umpqua, and Willamette National Forests.

Wet meadow -- Areas where grass predominate. Normally waterlogged within a few inches of the ground surface.

Wild populations -- Fish that have maintained successful natural reproduction with little or no supplementation from hatcheries.

Wild Rivers -- Rivers or sections of rivers that are free of impoundments and generally inaccessible except by trail, with watersheds or shorelines essentially primitive and waters unpolluted.

Wild stock -- A stock that is sustained by natural spawning and rearing in the natural habitat, regardless of parentage (includes native).

Wildfall -- Trees or parts of trees felled by high winds.

Wildlife -- Mammals and birds, game and non-game species that are not domesticated.

Wildlife tree -- A live tree retained to become future snag habitat.

Windthrow -- A tree or trees uprooted or felled by the wind.

Woodland -- Forest land producing trees not typically used as saw timber products and not included in calculation of the commercial forest land allowable sale quantity.

Woody debris -- Referring to wood in streams.

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Xeric -- Dry.

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Year class (or cohort) -- Fish in a stock born in the same year. For example, the 1987 year class of cod includes all cod born in 1987, which would be age 1 in 1988. Occasionally, a stock produces a very small or very large year class which can be pivotal in determining stock abundance in later years.

Yearling -- A one year old fish.

Yield -- The weight or number of fish removed by fishing during a defined time period.

Yield-per-recruit -- The expected lifetime yield-per-fish of a specific age (e.g., per age 2 individual). For a given exploitation pattern, rate of growth, and natural mortality, an expected equilibrium value of Y/R can be calculated for each level of F.

Yolk -- The food part of an egg.

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Zooplankton -- Small aquatic animals that are suspended or swimming in water.

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