Tribe’s steelhead monitoring could inform Skagit River fisheries

Following a pandemic-necessitated break in annual data collection, the Upper Skagit Indian Tribe this year resumed a test fishery for Skagit River steelhead. 

The test fishery provides insight into how many, when and where in the river winter steelhead are returning to spawn. The 2023 data is the eighth year’s snapshot collected since 2013. 

“Before this test fishery, abundance, timing and distribution were not well-documented for Skagit River steelhead,” said Garrett Rowles, the tribe’s stock assessment biologist.

During the test fishery, the tribe’s staff ply the river by boat upstream of Sedro-Woolley. At set locations, they let out a tangle net, drift for a short time, then haul the net in along with any fish caught in its weave. 

A steelhead is pulled onto the Upper Skagit Indian Tribe’s research boat in March 2023.

The net has come in with anywhere from zero to a few dozen fish for the team to sample per site. 

After each catch, entangled fish are freed from the net and placed in an in-river enclosure near the shore. One by one, the fish are lifted in a cradle net and moved to the riverbank for examination.

The sex and length of each fish is noted, along with whether it appears the fish has already or is prepared to spawn, and whether the adipose fin is intact. (Hatchery fish have had their adipose fins clipped before release to distinguish them from natural-origin fish.) 

Each silvery body is also scanned for passive integrated transponder (PIT) tags, which track fish that previously passed through the hands of researchers.

A small portion of the tail is cut and kept for DNA analysis in a lab, along with six scales plucked from each fish.

Finally, a PIT tag is inserted into the back of any fish that don’t yet have one. If a steelhead carrying a PIT tag passes a passive integrated transponder antenna array stationed along the Skagit River, it will be detected and scanned, providing researchers with more clues as to the movements of the individual. 

After its assessment and tagging, each fish is released back into the river. 

All of the data gathered is important for understanding the health of the Skagit River steelhead population, which has long been below its historical run sizes.

“So far, this test fishery has been successful in providing information on the size, age structure and abundance of returning steelhead as well as the male-to-female ratio throughout the run,” Rowles said. 

Steelhead, like salmon, are born in freshwater streams, migrate to sea for a period of time, and return to their natal waters to spawn. Unlike salmon, steelhead can survive spawning and may complete multiple rounds of migration throughout their lives. 

A shifting focus

Since its inception in 2013, the Upper Skagit Tribe’s test fishery has twice had to adjust to new factors in fish management. First, a program producing hatchery steelhead on the river closed in 2014.

“This test fishery was originally started in an effort to better understand the progression of the early-returning hatchery steelhead run and its overlap with the later-returning natural-origin steelhead,” Rowles said. 

Later, a recreational catch-and-release fishery was opened in 2018. That fishery now occurs annually, depending on the forecast run size. 

Throughout these changes, the tribe’s test fishery has continued as a way to monitor year-by-year variations in the natural-origin steelhead run size and to help inform fishery decisions, which are co-managed by the Washington Department of Fish and Wildlife (WDFW) and tribes with treaty rights to fish the Skagit River. The test fishery runs mid-February through late April.

Mid-season this year, the National Oceanic and Atmospheric Administration’s fisheries department approved a 10-year renewal of the harvest management plan for Skagit River steelhead.

That plan concludes that some fishing can take place without jeopardizing the continued recovery of threatened fish in the Puget Sound region, including steelhead, chinook salmon and bull trout, all of which are listed under the Endangered Species Act.

“That’s a good thing, obviously. But the bad thing is there aren’t many fish,” said Scott Schuyler, the Upper Skagit Tribe’s natural resources director.

The plan allows for the test fishery, some cultural and subsistence tribal fishing, and some directed tribal harvest and recreational fishing to take place if certain thresholds are met for the estimated run size each year. The Upper Skagit, Swinomish and Sauk-Suiattle tribes developed the plan cooperatively with WDFW. 

A similar plan was in effect from 2018 through 2022, but returns were not strong enough to support fisheries in 2020 and 2022.

In the decade ahead, the Upper Skagit Tribe’s test fishery could help ground-truth how the number of steelhead returning to the river matches up with the forecast, informing an in-season update about fish abundance for tribal and WDFW co-managers. A model for this purpose is being tested, Rowles said.

“This places even more importance on the test fishery,” he said. “In-season updates on run size provide valuable information for fisheries management, as they are based on observed numbers of returning fish for that run, rather than a preseason forecast which is entirely predictive.”

Above: (Left) Garrett Rowles, stock assessment biologist for the Upper Skagit Indian Tribe, carries a steelhead from a holding pen in the Skagit River to a data-collection area on the riverbank during a test fishery in March 2023. (Right) Rowles measures the length of a steelhead while field biologist Chris Kohn takes notes about fish size, sex and whether it had spawned.   

At top: A steelhead is pulled onto the Upper Skagit Indian Tribe’s research boat during the test fishery. Photos and story: Kimberly Cauvel.