WDFW studying chinook returns to Snohomish River basin

OLYMPIA - A study aimed at improving management of federally protected chinook salmon will get under way next week, when Washington Department of Fish and Wildlife (WDFW) biologists expand efforts to monitor and track chinook returns to the Snohomish River basin.

Biologists will be capturing, marking and releasing chinook salmon on the Snohomish, Skykomish and Snoqualmie rivers as the fish make their way upriver to the spawning grounds. Survey crews will then document the marked salmon found on the spawning grounds and caught in the sport fishery, as well as those fish that return to the Wallace River Hatchery and WDFW's Sunset Falls fishway.

Information from the study will be used to assess the accuracy of traditional methods of estimating chinook returns, said Pete Hahn, a WDFW fish stock assessment specialist in charge of the study.

"Having accurate population information is a vital part of fisheries management," Hahn said. "This study will help us improve estimates of chinook salmon abundance in the Snohomish River basin."

Crews will be capturing salmon - primarily with two soft-meshed beach seine nets - Mondays and Thursdays of each week through mid-October. The fish will be fitted with a visible anchor tag and implanted with a small "PIT" (passive integrated transponder) tag, both of which provide information on the background of each individual salmon.

Hahn asks anglers who hook a tagged salmon to call Michael Mizell, a biologist with WDFW, at 360-902-2740 and provide the tag number and information on when and where the fish was caught. He encourages anglers who are releasing salmon to leave the anchor tag in the fish.

People who find a tagged salmon carcass also are asked to leave the tag in the fish and report the tag number to Mizell.

State and tribal crews will be surveying the basin's spawning areas beginning in September. The crews will be tallying salmon carcasses and cataloging information from the fish equipped with tags.

Hahn said information collected by survey teams will allow WDFW to make a population estimate, which will be compared to other estimates made by counting salmon spawning nests, known as redds. Crews count redds by helicopter and by floating the spawning grounds in rafts.

Between 5 and 10 percent of the fish caught also will be fitted with small radio transmitters that are inserted into the stomach. The transmitters, which have a thin, flexible antenna extending from the salmon's mouth, send out a constant signal that WDFW crews can track as the fish move upstream to spawn.

"The radio transmitters will let us follow the movements of individual salmon, giving us a better understanding of where these fish go, where they hold before they spawn and what rivers and tributaries they end up in," Hahn said.

Anglers who catch and keep a hatchery salmon fitted with a radio transmitter also are asked to contact Mizell.

Funding for the study is provided by the Pacific Salmon Commission. The commission oversees the Pacific Salmon Treaty, which defines how the U.S. and Canada conduct salmon fisheries.