Glossary
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Captive brood stock
Fish raised and spawned in captivity.
Carnivorous
Feeding on animal tissues.
Cartilaginous fishes
A major group of fishes including sharks and rays.
Cascade
A series of small steep drops increasing the velocity of the stream.
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 release or retention.
Catch curve
A graph of the logarithm of number of fish taken at successive ages or sizes.
Catch per unit 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. Ex: tons of shrimp per tow, pounds of fish per hundred longline hooks.
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 coefficient" or "force of fishing mortality".
Catch-At-Age
Number of individuals in each age class caught from one stock.
Catchment
The area which supplies water by surface and subsurface flow from precipitation to a given point in the drainage system.
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.
Channelized
A portion of a river channel that has been enlarged or deepened, and often has armored banks.
Chinook salmon
An anadromous salmonid of the genus Oncorhynchus and species tshawytscha. Also known as king, spring, or blackmouth salmon.
Chum salmon
An anadromous salmonid of the genus Oncorhynchus and species keta. Also known as dog salmon.
Coastal juveniles
Juvenile salmonids inhabiting the waters of the continental shelf.
Coded-wire tag
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.
Coho salmon
An anadromous salmonid of the genus Oncorhynchus and species kisutch. Also known as silver or hooknose salmon.
Compensatory mortality
Mortality is compensatory when the mortality rate (i.e., proportion of population affected) decreases as the population size decreases. This is in contrast to depensatory mortality, were the rate increases as the size of the population decreases.
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.
Conspecific
Individuals of the same 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.
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
A measurement of stream flow.
Cultured stock
A stock that depends upon spawning, incubation, hatching, or rearing in a hatchery or other artificial production facility.
Cycloid scales
Smooth, flat, round scales that have concentric lines called circuli, found on trout, herring, and other fish.