WDFW teams with commercial trollers to improve data on chinook salmon harvest

OLYMPIA - Scientists with the Washington Department of Fish and Wildlife (WDFW) teamed with commercial fishers this year on a pilot project that used advanced genetic tests to quickly determine the origin of chinook salmon caught off the coast.

By employing high-tech tools to analyze the DNA of salmon tissue samples, WDFW scientists determined within a day the home watershed of many chinook salmon caught during the eight-week commercial troll fishery off the Washington coast. In those waters, several different salmon stocks mingle, including both harvestable and protected weak populations.

WDFW has conducted genetic tests of commercial and sport-caught salmon for two decades, but processing the samples often took weeks, said Scott Blankenship, a geneticist with the department.

"This collaborative approach allows us to gather near real-time information about the stock composition of harvested salmon while a fishery is still in progress," Blankenship said. "That could further help in directing fishing fleets away from weak salmon stocks and toward abundant harvestable fish."

While the project shows potential, several more years of collaborative work will be needed before biologists can determine how to best use these new methods more widely in fishery management, Blankenship said.

Several commercial trollers - who fish with hooks and lines - participated in the project, which took place in May and June. Once a salmon was caught, they entered the harvest location and time with a Global Positioning System, took scale and tissue samples, measured the length and noted whether it was a wild or hatchery salmon. Hatchery salmon are marked with a missing adipose fin.

When the trollers returned to port and unloaded their catch, the information was delivered to WDFW's Molecular Genetics Laboratory, where technicians processed the tissue samples.

Results are being compared with data gathered through traditional methods used by WDFW to determine salmon stock composition in the ocean troll fishery.

Blankenship said preliminary data from the project shows the percentage of Puget Sound chinook caught during the May and June commercial fishery matches the department's preseason expectations. There were some variations, however, including a higher than expected catch of upper Columbia River summer and fall chinook.

"With the help of commercial fishers we can work to improve our understanding of the distribution of salmon stocks in Washington's ocean waters and better manage harvest to protect wild fish," Blankenship said.