CRiSP Harvest Model Glossary

Columbia Basin Research hosts this web page for archival purposes only. This project/page/resource is no longer active.
Abundance Index
The expected catch given the current year size limits and cohort sizes but the base period (1979-1981) harvest rates.
Adult Equivalence Factors
Used to adjust fishery catches to a common impact on the spawning stock. For example, on average a three year old fish harvested by an ocean fishery has less impact on the spawning stock than a five year old fish harvested by a river fishery, because some three year old fish would normally die of natural causes before they had an opportunity to spawn. Thus, one three year old fish eliminated from the ocean catch will result in less than one additional fish in the spawning stock, whereas one five year old fish eliminated from the river catch will result in one additional fish in the spawning stock.
Adult Escapement
Terminal Run fish that survive the terminal fisheries and pre-spawning mortality. Age two fish returning to the river are not considered reproductively viable and are not included in the adult escapement for each stock.
Base Period Harvest Rate
Average stock, age, and fishery specific harvest rate between 1979-1982. Harvest Rate scalars are relative to this rate.
Brood Year
The year in which a fish was propogated or spawned (i.e., the year in which the eggs were fertilized). Chinook salmon typically migrate downstream the following year (most Fall chinook), or the year after (most Spring chinook).
Catch Ceilings
Maximum catch (numbers of fish) for a fishery or group of fisheries for a specified time period. These are not established for specific stocks. This is the Pacific Salmon Commission's primary management tool.
Chinook Non-Retention Mortalities
Mortalities of legal and sub-legal chinook that are caught and brought up to the boat in coho fisheries at times when it is not legal to land and sell any chinook.
CNR (mortalities)
See Chinook Non-Retention Mortalities.
Coded-Wire-Tag (CWT)
Tiny wire tags (1.0 x 0.25 mm) inserted in the nose cartilage of salmon fingerlings or fry, typically in the hatchery, to identify the origin of an individual fish. Each tagged fish has the adipose fin clipped to indicate that it has a CWT in its snout. Scientists use CWT recoveries to estimate harvest rates and migration patterns.
Cohort
A group of fish that have the same demographic characteristics, such as belonging to the same age class of a given stock.
Cohort Analysis
Same as Virtual Population Analysis.
Enhancement
Production of fish at facilities such as hatcheries.
Escapement
Fish that are not caught by any fisheries (i.e, they "escape" the fisheries).
EV Scalar
Scalars used to adjust the average production of age one fish by a spawning stock to account for inter-annual Environmental Variability (EV).
Gillnet
A harvest method in which fish are trapped in a net stretched across their migration path. The net may either be set from a drifting boat (drift gillnetting) or from a fixed position (set gillnetting). The fish become entangled by their gill plates or jaws, and can neither back out nor move forward.
Harvest Rate Scalars
Scalars used to adjust the harvest rate during a given year compared to the Base Period.
IDL (rate)
See Inter-Dam Loss rate.
Inter-Dam Loss rate
These are actually survival rates between the last fishery and the spawning grounds. Also called the Pre-spawning mortality. IDLs are stock specific, but are not age (or size) specific. This mortality is applied to Columbia River stocks that spawn upriver from dams and is assessed after fishing mortality to account for losses between dams.
Legal (size)
Above a certain size criteria.
Maturation Rates
The proportion of a stock that is mature and ready to return to the spawning ground. These are age and stock specific and can vary across years as well. However the model does not allow for age 6 fish so the MR for age 5 fish should always be 1. The stock that is mature is considered the terminal run.
Monte Carlo Mode
Running the model using random brood year survival rates during the simulation period.
Natural Ocean Mortality
Non-fishing mortality assessed at the beginning of each year in the model. This mortality is age specific, but not stock specific.
Net Fisheries
In CRiSP Harvest, this refers to fisheries using gillnet and purse seine gears.
Pacific Salmon Commission
International regulatory agency created by the 1985 Pacific Salmon Treaty between the United States and Canada with responsibility for management of North American salmon stocks and fisheries.
Percent Non-Vulnerable
Fraction of a cohort that is below the legal size limit. PNVs vary by year, age, and fishery, but not by stock.
PNV
See Percent Non-Vulnerable.
Pre-Spawning Mortality
See Inter-Dam Loss.
Preterminal (catch)
Catch that occurs before the mature segment of a cohort begins migrating back to the spawning grounds. Thus, preterminal catches are primarily ocean catches.
PSC
See Pacific Salmon Commission.
Purse Seine
A commercial fishing system in which a school of fish are encircled by a vertically hanging net and then are trapped by closing the bottom of the net (pursing).
Recruitment
Fish from a given stock that become available (i.e., recruit) to a fishery.
Recruitment Age
The age at which fish from a given stock become available to a fishery.
Ricker Function
A popular type of Spawner/Recruit Relationship (named after Dr. William Ricker) in which the number of recruits per spawner declines exponentially. The resulting curve has a desending right hand limb (i.e., too many spawners produce fewer recruits).
Shakers
Sublegal chinook that are caught (i.e., hooked and brought up to the boat) and released (i.e., "shaken" off the gear) during directed chinook fisheries.
Spawner/Recruit Relationship
A mathematical relationship between the number of spawners in a given year and the resulting number of progeny that become available (i.e., recruit) to the fisheries in some future year. Usually estimated from historical data and used in simulation models to predict future recruitment from a given spawning stock.
Sub-legal (size)
Below a certain size criteria.
Supplementation
Artificial propogation intended to reestablish or increase the abundance of natural populations.
Terminal Catch
Catch of the mature segment of a cohort as it migrates back to the spawning grounds. Some ocean net catches that occur in nearshore waters are considered terminal catches.
Terminal Run
Mature fish leaving the open ocean and returning to the spawning grounds. Compare to True Terminal Run.
Total Catch
Sum of the Preterminal and Terminal catches.
Troll
A commercial harvest method for chinook and coho salmon, usually in the open ocean, that captures individual fish on lures or baited hooks being slowly pulled through the water.
True Terminal Run
The Terminal Run minus nearshore ocean net catches. Thus, it is the number of fish entering the natal river (as opposed to the number of mature fish leaving the ocean feeding areas). Compare to Terminal Run.
Virtual Population Analysis
A technique (sometime referred to as VPA) for reconstructing the history of a cohort of fish. By counting the number of spawners and the catches and making estimates of the natural mortalities it is possible to reconstruct the history of a cohort.