Recycling of hatchery summer steelhead in the lower Cowlitz River presents minimal risk to wild fish in the system, a preliminary U.S. Geological Survey study says.
“Intensive monitoring of the key spawning tributaries failed to detect a single fish during the spawning period,’’ according to the executive summary of the research, done in 2012 and 2013.
The Washington Department of Fish and Wildlife and Tacoma Power also participated in the research.
Historically, summer steelhead returning to Cowlitz Salmon Hatchery were recycled to the lower river to give sportsmen a second chance.
Recycling ended over the concern that non-native hatchery steelhead might stray into lower Cowlitz tributaries and cause negative effects on the native wild winter steelhead known to spawn in the streams.
The Columbia River Salmon and Steelhead Endorsement Advisory Board approved a grant of $140,000 to study the recycling of steelhead. The money came from the $8.25 fee paid by anglers who fish the Columbia River and its tributaries.
Summer steelhead enter the Cowlitz beginning in May and return to the hatchery through early December.
Some are used as spawning stock, while the excess go to food banks.
The steelhead sport fishery on the Cowlitz is very popular.
A total for 549 summer steelhead were captured at Cowlitz Salmon Hatchery in the summer of 2012, tagged and released downstream near the Interstate 5 Bridge. All the recycled fish had a visible white tag, and a hole punched in their opercle (gill cover). Twenty percent of the fish were radio-tagged.
Three fixed telemetry monitoring sites were established on the main Cowlitz River and eight additional sites were deployed on tributaries of the lower Cowlitz where wild winter steelhead are known to spawn.
Mobile tracking from a boat also was conducted in October and November of 2012 and January of 2013 to locate radio-tagged fish.
A creel survey and voluntary angler reports were used to determine the number of recycled steelhead caught by sportsmen.
Researchers determined that 50 percent of the recycled steelhead returned to the hatchery. The average elapsed time from recycle release to recapture at the hatchery was nine days.
Eighteen percent of the recycled steelhead were caught by fishermen within about 10 days.
When river flows were increasing, steelhead were more prone to return to the hatchery. When river flows were decreasing, sport catches were better.
No radio-tagged steelhead were detected in any tributaries except one fish that spent approximately seven days during early September in the Toutle River.
Almost one-third of the recycled steelhead made at least two trips between Cowlitz Trout Hatchery and the barrier dam near Mayfield Dam. Some fish made as many as six trips.
Radio-tagged steelhead that remained in the lower Cowlitz during the December-January spawning period were observed between Ostrander Creek and Cowlitz Trout Hatchery.
There was no accounting for 32 percent of the recycled steelhead.
“Findings from the radio telemetry study suggest that unreported harvest or mortality could explain a large portion of those fish that were not reported as having been removed from the river,’’ the study says.
Ten of the 11 steelhead that were determined to have died or regurgitated their transmitter were close to popular boat ramps and fishing locations.
“This observation would suggest that anglers contributed to this distribution because we would expect these transmitters to be more randomly distributed throughout the system if mortality or transmitter regurgitation was occurring through random chance,’’ the study says.
The failure to find any of the recycled steelhead in the spawning tributaries also was supported by observations from weir traps operated by the Department of Fish and Wildlife on Salmon, Olequa and Delameter creeks.
Wolf Dammers, district biologist for the Department of Fish and Wildlife, said the field work on a second year of research is done and a report is anticipated in the spring.
The Cowlitz Fishery Technical Committee, which includes the state and federal fish agencies and Tacoma Power, need to review the research, he said.
Tacoma Power operates the hydroelectric dams on the Cowlitz and finances hatchery operations.