WILLOW, ALASKA — The Alaska Department of Fish and Game closed the Deshka River and the Susitna River drainage to sport fishing for king salmon under a state emergency order. The number of king salmon returning to the Deshka River to spawn failed to meet minimum standards from 2022 to 2025. According to the agency, the number of king salmon observed swimming past a state-operated weir in 2025 was the lowest on record.

Northern pike are an invasive species in areas south of the Alaska Range, a 600-mile expanse of mountains. They were likely introduced illegally in Alaska in the 1950s and have since spread throughout much of Southcentral Alaska, including more than 150 waterways around Anchorage and in the Matanuska-Susitna region.

A peer-reviewed paper published in the journal Biological Invasions in February 2024 found that northern pike in Southcentral Alaska are consuming more prey as water temperatures warm. The study, led by researchers at the University of Alaska Fairbanks, contrasted the stomach contents of pike from the Deshka River in 2021 and 2022 with samples from a decade prior. Year-old northern pike in the recent samples had eaten 63 percent more, with increased consumption rates observed across all age groups.

Mean air temperatures in the study area have warmed by approximately 3 degrees Fahrenheit since 1919 and by 0.8 degrees Fahrenheit in the decade preceding the study. Peter Westley, a University of Alaska Fairbanks fisheries professor, stated, "Their ability to capture prey goes up when it's warm and then their consumption demands go up." Scientific models included in the study predict a 6 percent to 12 percent increase in northern pike appetites by 2100.

Research conducted by the University of Alaska Fairbanks and the Alaska Department of Fish and Game determined that northern pike can navigate through saltwater. This conclusion was based on studying the chemical signatures present in the otoliths, or ear bones, of pike caught near Anchorage and on the Kenai Peninsula. The research team inferred that these predatory fish traveled through Cook Inlet, a 180-mile estuary that connects the Gulf of Alaska with Anchorage and major river systems. The Alaska Department of Fish and Game has previously eradicated northern pike on the Kenai Peninsula.

Mike Williams, a retired Army veteran, described the impact of the pike invasion. He and his wife, Paula, formerly operated a remote sport fishing lodge near Mount Susitna, which depended on salmon and trout from Alexander Creek, a tributary of the Susitna River. Williams said that approximately two dozen fishing lodges once operated in the Alexander Creek drainage, but most closed in the early 2000s. By 2009, their EagleSong lodge was the last remaining fishing lodge in the area. "Everybody shut down and boarded up and left to find work," Williams said. He added that the abundance of bears, wolves, and ducks in the area has decreased since the decline of salmon in Alexander Creek.