Invasive pike uses marine corridors to establish new territory in Alaska

An exotic species of northern pike caught in Vogel Lake on Alaska’s Kenai Peninsula is on display. Credit: Rob Massengill, Alaska Department of Fish and Game
According to a recent study published in the journal PLOS ONE, northern pike are invading freshwater habitats in southcentral Alaska through saltwater.
Researchers from the University of Alaska Fairbanks and the Alaska Department of Fish and Game made the discovery by collecting and analyzing tiny otoliths, called otoliths, from northern pike caught in the area. This is the first known record of northern pike moving to colonize new territories in North America through estuaries, where fresh water from rivers mixes with the ocean.
The discovery provides new insight into the ongoing spread of northern pike across southcentral Alaska. The northern pike, a native species of interior and western Alaska, was illegally introduced to the Susitna River watershed in the 1950s. Since then, this predatory fish has become established in more than 150 lakes and rivers in the region.
Previously, the spread of northern pike was thought to be limited to freshwater corridors or trespassing by people.
“They are freshwater fish, and Cook Inlet was thought to be a marine barrier that prevented them from moving from one basin to another,” said Matthew Wooler, a professor in UAF’s College of Fisheries and Marine Sciences and lead author of the paper. said. .
Wooler, who is also director of UAF’s Alaska Stable Isotope Facility, led the team’s efforts to recreate the pike’s movements by analyzing otoliths collected by ADFG starting in 2019. The composition of strontium isotopes in the otolith layers may be consistent with chemicals. Traces in various waterways show where the fish have traveled during their lifetime.
“Sstrontium varies by geology and location,” says Uhler. “If pike are migrating between basins, we can catch them by analyzing the strontium in their otoliths.”
The study found three pike from three separate locations with isotopic signatures consistent with upper Cook Inlet waters, suggesting they occupied the entrance at some point. These fish were caught in freshwater habitats connected to Cook Inlet: Campbell Lake and Westchester Lagoon in Anchorage, and Vogel Lake on the Kenai Peninsula. The discovery highlights the tough challenge of limiting the spread of northern pike in this region. This suggests that waterways connected to the ocean where northern pike have been eradicated may be reintroduced.
As efficient predators, pike have an impact when native fish species, such as salmon, invade new territory.
The new recognition that fish are migrating through estuaries is “just another reason why the northern pike is typical of what creates a formidable invasive species,” said Dr. said Peter Westley, UAF Fisheries Associate Professor. and introduced the series for over 10 years.
Despite the concerns, the new research could also lead to more targeted action against invasive fish.
“Confirming that northern pike can use this pathway provides us with the information we need to prevent this spread and focus our efforts on protecting valuable habitat in the future,” said Parker Blood, ADFG invasive species biologist. Mr. Lee said.
“These findings will help direct resources to pike-free monitoring areas that are most at risk of invasion,” said Kristin Dunker, who coordinates the ADFG program to manage the invasive northern pike in southcentral Alaska. It will be helpful.”
“This discovery is a step forward in our scientific understanding of northern pike ecology in North America, and in the management of the invasive northern pike here at home,” Professor Dunker said.
In addition to Wooler, Bradley, Dunker and Westley, contributors to the paper included UAF’s Karen Spareta and former ADFG Robert Massengill.
Further information: Matthew J. Wooller et al. Estuarine dispersal of invasive horctic predators (Esox lucius) identified in North America, PLOS ONE (2024). DOI: 10.1371/journal.pone.0315320
Provided by University of Alaska Fairbanks
Citation: Invasive pike uses marine corridors to colonize new territory in Alaska (January 15, 2025) https://phys.org/news/2025-01-invasive-pike-marine-corridors Retrieved January 15, 2025 from -colonize.html
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