Treaty tribes and partners are looking for juvenile chinook salmon where they aren’t expected to be found.
In partnership with King County, the Suquamish and Tulalip tribes want to know where and how many juvenile chinook salmon are using non-natal streams in Puget Sound during their migration to the ocean.
From February through May, scientists are looking at 35 streams throughout central Puget Sound, from Mukilteo to Dash Point on the eastern shores, from Point No Point to Olalla on the western shores, and on Bainbridge and Vashon islands.
Juvenile chinook recently have been observed taking refuge in freshwater creeks and estuaries along shorelines that are not known to support chinook spawning, said Steve Todd, the Suquamish Tribe’s salmon recovery biologist.
“Because central Puget Sound has lost much of its natural estuary habitat, non-natal streams may be important rearing habitats for juvenile chinook,” he said.
Scientists at the Tulalip Tribes and Skagit River System Cooperative have a model based on findings from small stream surveys in the Whidbey basin, said Todd Zackey, the Tulalip Tribes’ field studies program manager.
“This study is to see if and how juvenile chinook use central Puget Sound, and update and refine the model developed for the Whidbey basin,” he said.
Chinook salmon populations and their habitat have been impacted by human-driven changes, such as pollution, deforestation and development. Puget Sound chinook are listed as threatened under the federal Endangered Species Act.
Objectives of the study include identifying when and where juvenile chinook salmon are rearing within Puget Sound, and determining where juvenile chinook may rear based on habitat features, said Theo Suver, a field biologist with the Suquamish Tribe’s ecosystem recovery program.
The study’s first data collection included surveying the quality of habitat conditions in the first 150 meters of the selected streams last fall, including looking at channel gradient, channel width, presence of woody debris, water temperature and conductivity.
This spring, scientists are electrofishing the same reaches, counting and measuring all species found. Electrofishing sends an electric circuit into the water, stunning the fish or encouraging them to swim toward the electric field for survey collection.
A fin clip from sampled chinook is sent to the Washington Department of Fish and Wildlife to be analyzed for river origin or genetic assessment of the stock. Water samples taken by the Suquamish Tribe will be tested for eDNA to compare electrofishing and eDNA methods to determine fish presence.
A juvenile coho salmon sampled from Klebeal Creek in March. Story and photos: Tiffany Royal
