Salmonid Stock Inventory (SaSI)

Abundance -- the size of a salmonid  population or of a component of the population expressed as  numbers of  fish.

Allele -- One of two or more alternate forms of a gene.

Anadromous fish -- Fish that hatch in fresh water, mature in salt water, and return to fresh water to spawn.

Brood year -- the offspring of parents that spawned during a single spawning season.  The 2000 brood of a stock would be the offspring of the fish that spawned in 2000, regardless of the age of the spawners.

Coded-wire tag (CWT) -- short (about 1 mm long) lengths of wire imprinted with a numeric code that are implanted in juvenile salmon prior to release or outmigration.    When recovered, the code on the tag provides specific information about the individual's tag group (e.g., tagging location (for wild fish), location and timing of release, special hatchery treatments).  A tagged hatchery fish usually has its adipose fin removed to signal tag presence. 

Chronically low -- in SaSI this term refers to production or survival that has been lower than expected for an extended period.  The status of stocks judged to have chronically low production would be rated depressed or critical.

Composite (production type) -- spawning in both the natural environment and in a hatchery or other artificial production facility.

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.

Cultured (production type) -- spawning, incubation, hatching, or rearing in a hatchery or other artificial production facility such as a spawning channel or spawning beach.

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

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

Escapement -- That portion of a run that is not harvested and escapes to natural or artificial spawning areas.

Extinct stock -- A stock of fish that is no longer present in its original range, or as a distinct stock elsewhere. Individuals of the same species may be observed in very low numbers, consistent with straying from other stocks.

Fingerling -- Juvenile salmonids up to nine months of age and generally two to four inches in total length.

Fish-days -- the number of fish counted multiplied by the number of days over which counts were made.  Fish-days are used to estimate escapements, particularly in areas where spawners are passing through but generally not spawning.  Fish-days provide a “snapshot” of the escapement.

Fry --  Young salmonids that have emerged from the gravel and are up to one month in age.

Gene -- A specific unit of genetic material (DNA) that encodes the information for a single inherited trait.

Genetic analysis -- In SaSI, comparison of allele frequencies (for allozymes or DNA sequences) to determine genetic similarities and differences among stocks of fish.

Hatchery origin -- the progeny of fish that were spawned in a hatchery or other artificial production facility.

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

Hybridization -- The interbreeding of fish from two or more different stocks or species.

In-river run size -- the abundance of the run entering a river or river system, after all marine harvest mortalities, but prior to any in-river fishing mortalities.

Independent tributary -- A small stream flowing directly into marine waters.

Index area -- a portion of a stream in which spawner or redd densities are thought to be typical for the entire stock.   In some cases the counts can be expanded to total escapement estimates for  the stock.

Long-term negative trend -- about ten years of stock data showing a consistent decline in a production or survival parameter.  The status of stocks showing a long-term negative trend in production would be rated depressed or critical.

Mainstem -- A major stream channel which is joined by numerous tributaries.

Management Unit -- a stock or group of stocks which are aggregated for the purpose of achieving a desired spawning escapement objective.

Mixed (stock origin) -- a stock composed of commingled native and non-native parents and/or by mating between native and non-native fish or a previously native stock that has undergone substantial genetic alteration.

NMFS (National Marine Fisheries Service) -- the branch of the National Oceanic and Atmospheric Administration, Department of Commerce, which is responsible for administering the federal Endangered Species Act for most anadromous salmonids in the U.S.  NMFS is now known as NOAA Fisheries.

Native (stock origin) -- an indigenous stock of fish that has not been substantially impacted by genetic interactions with non-native stocks or by other factors (such as artificial selection) and is still present in all or part of its original range.

Non-native (stock origin) -- a stock of fish that has become established outside of its original range.

Natural-origin recruit (NOR) -- The offspring of fish that spawned in the natural environment and which also spawn in the natural environment.

Outmigrating juveniles -- salmonid smolts that are migrating from fresh water to saltwater.

Productivity -- a stock’s intrinsic rate of increase, which determines the stock’s ability to withstand mortality. 

Redd -- a depression in streambed gravel dug by a female spawner where she deposits her eggs. 

Return year -- fishmaturing and returning to spawn in a single spawning season.

Short-term severe decline -- Two of the last five years of stock production or survival data showing a marked drop.  This criterion serves as an early warning that a stock may be experiencing a decline so that corrective measures can be taken before serious damage occurs.  The status of stocks showing a short-term severe decline in production would be rated depressed or critical.

Spawning escapement -- the number of salmonids of a single stock on the spawning grounds that presumably spawned.

Stock -- a group of fish within a species which is substantially reproductively isolated from other groups of the same species. 

Terminal area -- the portion of the migration route of fish returning to fresh water to spawn where a stock or multi-stock run of fish splits off from a larger mixed run of fish.  Terminal areas may be in marine waters or fresh water.

Terminal run size --  an estimate of the number of fish of a species entering a terminal area. 

Total escapement -- an estimate of the escapement of an entire stock, often based on counts of spawners or redds in representative portions of the stock’s spawning areas.

Unfed fry -- hatchery fish that are released shortly after emerging from gravel and are not fed enough that significant growth occurs prior to release.

Wild (production type) -- spawning and  rearing in the natural habitat, regardless of parentage (includes native, non-native and mixed stock origin).