Stock Assessment

The purpose of the Tulalip Stock Assessment Laboratory (TSAL) is to collect and analyze biological samples and data from juvenile and adult salmon and steelhead in regional fisheries, hatcheries, and streams in order to responsibly co-manage natural resources under the Tribes’ jurisdiction as mandated under existing treaties, court orders, and terms and conditions of permits and management plans.

Because today’s hatchery operators must monitor hatchery fish after release and their potential for genetic and ecological interactions with natural-origin juvenile and adult fish, a number of different types of marks and tags are given to the Tribe’s hatchery fish before the juvenile fish are released. First, all (100%) of the Chinook, coho, and chum salmon raised by the Tribe are uniquely marked by hatchery of origin and brood year when they are tiny eggs by changing the water temperature in particular sequence that can be identified later in set patterns in their otoliths. Otoliths are calcium carbonate mineral deposits sometimes called “stones” or “ear bones” that form daily rings as they are deposited inside the fish’s head, resembling the annual growth rings in trees. Temperature changes form marks on the otolith rings similar to bar codes that can later be read in our lab. Small rubbery adipose fins near the tail are removed from approximately 5 million juvenile Chinook and coho salmon originating from the Tulalip hatchery annually. An additional 450,000 of the tribe's juvenile Chinook and Coho hatchery production are marked with small metal "coded-wire" tags that are inserted into their snouts before they are released. These tags can be identified later using metal detectors and their laser-imprinted tag numbers read under the microscope.

After release, the Tribe conducts an extensive sampling program to recover thousands of these marks, tags and tissue samples from juveniles in regional streams, estuaries, and the marine areas of Puget Sound and later, when they return as adults, from regional fisheries, hatcheries, and rivers. The fin clips help to externally identify them in fisheries as hatchery fish while they are still alive so that the clipped hatchery fish can be kept in mark-selective fisheries, while the unclipped natural-origin fish can be released. The coded-wire tags, along with the otoliths, are sampled at the docks to estimate the stock composition in the fisheries, which enables the Tribes to continue to demonstrate that their fisheries in Tulalip Bay are principally targeting the hatchery production with very little impact on natural stocks. A combination of otoliths, tags, and clips recovered from the adult spawners in regional rivers and hatcheries are used to identify hatchery-origin fish and estimate their abundance on the local spawning grounds of the Snohomish basin. Scales are collected to identify the ages of natural-and hatchery-origin fish, how long they lived in rivers and in the ocean, and estimate their growth rates; while other tissue samples are collected for DNA analysis to identify the genetic composition and population structure of the naturally-spawning populations are from, examine run timing, and estimate gene flow between natural- and hatchery-origin fish.