The Upper Skagit Indian Tribe is tracking Skagit River juvenile steelhead before they out-migrate to salt water – if they out-migrate to salt water.
The tribe has been tagging juvenile steelhead with passive integrated transponder (PIT) tags for a few years to collect information about freshwater production in tributaries to the Skagit River. This year, they also are using Juvenile Salmon Acoustic Telemetry System (JSATS) tags, which can be detected at a greater distance than a PIT tag.
Steelhead smolts are collected in screw traps in Hansen Creek near Sedro-Woolley and Illabot Creek near Rockport. Upper Skagit natural resources staff implant fish with both tags.
Acoustic receivers at 11 locations along the Skagit River between Marblemount and Fir Island collect information about the juvenile fish while they’re in the river. In addition, Upper Skagit’s natural resources department is conducting mobile surveys using a receiver attached to the bow of a boat.
“Our goal is to gather biological knowledge about juvenile steelhead survival and the propensity to migrate to the salt water while refining the methodology along the way,” said Mike LeMoine, Upper Skagit fisheries biologist.
Steelhead have been listed as threatened under the Endangered Species Act (ESA) since 2007. Skagit River steelhead account for approximately 40 percent of all the steelhead in Puget Sound. The Upper Skagit Tribe wants to learn more about what might influence the migratory life history of Skagit River steelhead to develop an independent recovery plan and improve management.
Juvenile steelhead can leave freshwater habitat between their first and fourth year of life, and return from the salt water after one to five years. Because steelhead are genetically indistinguishable from rainbow trout in the Skagit River, understanding the factors driving migration is important.
Currently there is a lot of effort to understand steelhead early marine survival, LeMoine said. This research aims to fill in the data gaps for residualized steelhead – those that don’t out-migrate.
Already, researchers have observed a correlation between water temperature and steelhead behavior. With higher river temperatures since 2015, steelhead have been leaving the river at a younger age than before, which will likely influence how they survive to become adults.
“Oncorhynchus mykiss can mature either in the salt water as steelhead or fresh water as a rainbow trout,” LeMoine said. “Because they can interbreed with the other form, we must understand factors that influence survival and migration.”