A voracious, invasive fish that preys on salmon has seen its numbers grow in Lake Washington.
Muckleshoot Indian Tribe staff and fishers caught 85 northern pike during a four-week fishery in May and June during an ongoing project to net the big lake to reduce populations of non-native predatory fish.
While the tribe and Washington Department of Fish and Wildlife (WDFW) staff have sporadically encountered the ravenous predator since a first detection in 2017, the number found this year marks a worrisome increase. Last year, they saw only three.
A booming northern pike population will mean fewer salmon in the lake—and fewer chances to catch salmon, kokanee, trout and other fish for tribal and non-tribal fishers alike, said Jason Schaffler, the fisheries division director for the tribe.
“We don’t want them here. They’ll limit everyone’s opportunities in the future,” he said.
The pike were likely illegally transported and released into the lake. Pike are classified as a prohibited aquatic invasive species (AIS) under Washington state law.
Northern pike are large, growing up to 45 pounds, with spiky teeth. They are voracious eaters, mostly focused on soft-bodied fish but also willing to eat frogs and ducklings. They can reproduce quickly and severely damage ecosystems, and pose a particularly dire threat to juvenile sockeye salmon, which feed and grow in Lake Washington for up to two years before swimming into the ocean.
“They’ll eat anything they can fit in their mouths,” said Tiffany Armstrong, a biologist with the tribe. “They sit and wait for something to go by. If it’ll fit in their mouth, they’ll go after it. They eat a pretty hefty amount of salmon.”.
The tribe is exploring next steps including practicing invasive vegetation control — which would remove vegetation that serves as pike’s hunting grounds and nursing habitat — in an effort to limit the invasive fish’s reproductive output, and will delve into one question: Is the current northern pike population reproducing in the lake? If so, it may prove more difficult to control.
Coordinated response with tribe and state co-managers and expanded federal, tribal, state, and local funding partnerships will be essential to contain impacts and prevent long-term ecological and economic consequences.
In recent years WDFW also operated a state-funded project to suppress populations of non-native predatory fish that feed on salmon in Lake Washington. Despite requests from WDFW, co-manager tribes, and fishing and conservation organizations, this $1.4 million budget proviso was not funded by the State Legislature in the 2025-2027 biennium.
For now, tribal staff hope fishers know that northern pike are illegal to transplant in the lake, and should be killed immediately if caught. Pike may not be transported while alive anywhere in Washington.
If possible, fishers should also take a photo and report the northern pike by phone (1-888.WDFW-AIS) or email ([email protected]) to the Washington Department of Fish and Wildlife (WDFW) or through the online form at: invasivespecies.wa.gov/report-a-sighting.
Top: Northern pike caught in Lake Washington by the Muckleshoot Indian Tribe on May 6. Photos provided by the Muckleshoot Indian Tribe.
