PUYALLUP – Fewer juvenile wild chinook are migrating out of the Puyallup River this year, likely because winter floods washed away chinook redds before the fish had a chance to emerge from the gravel nests.
The Puyallup Tribe of Indians counts outgoing chinook with a smolt trap in the lower Puyallup River. The trap allows young salmon to be safely captured and released, providing an estimate of the watershed’s productivity. Smolts are juvenile salmon undergoing “smoltification,” a physiological process that allows them to survive their transition from fresh to salt water.
In early May, more than halfway through the out-migration season, only 34 chinook have been caught in the trap. That’s down from 2,500 chinook last year.
Because only a portion of the young chinook are caught in the trap, the must carefully analyze capture data before determining the size of the outmigration. A mild winter in 2007 resulted in the largest wild chinook outmigration ever recorded in the river: 89,000 wild chinook.
“It is possible that we’re seeing just a very late out-migration, but its much more likely that the chinook were killed during the winter floods,” said Russ Ladley, resource protection manager for the tribe.
A flood in 2006 had a similar impact on the 2007 out-migrating chinook population. After analysis, the tribe determined that only 10,000 chinook left the watershed that year, down from a peak of 60,000 fish in 2005.
“Because of habitat degradation, spawning and rearing habitat throughout the Puyallup watershed is limited,” Ladley said. “One flood can do a lot of damage.”
Historically, floods in the Puyallup Watershed were not as dangerous to salmon. “The nature of the watershed has changed dramatically, with dikes being built up right next to the river. An increase in impervious surfaces such as parking lots make stormwater all the more destructive,” Ladley said. “Water flows through the system at a much higher rate now, making floods more destructive for people and salmon.”
Low numbers of juvenile chinook migrating out to the ocean this year will mean even fewer adult chinook returning in three or four years from now, and that will mean restricted fisheries. “Chinook fisheries on the Puyallup, even fisheries on abundant hatchery stocks, are driven by impacts to the number of wild chinook returning in a particular year,” Ladley said. Puyallup River chinook are part of the Puget Sound stock listed as “threatened” under the federal Endangered Species Act.
“To sustain strong chinook runs from year to year, the fish need habitat to support them,” Ladley said. “In the past few years the tribe has worked with partners throughout the watershed to restore habitat for juvenile salmon, but those projects have only covered a fraction of the entire watershed.”
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For more information, contact: Russ Ladley, resource protection manager, Puyallup Tribe of Indians, (253) 845-9225. Emmett O’Connell, information officer, NWIFC, (360) 528-4304, [email protected].
