Invasive pike use marine corridors to colonize new Alaska territory

Northern pike are shifting via salt water to invade freshwater habitats in Southcentral Alaska, in step with a up to date learn about printed within the magazine PLOS ONE.

Researchers on the College of Alaska Fairbanks and the Alaska Division of Fish and Sport made the invention by means of gathering and examining tiny ear stones referred to as otoliths from northern pike stuck within the area. It is the first recognized documentation that northern pike are touring via estuaries, the place recent water from rivers mixes with the sea, to colonize new territory in North The united states.

The invention provides new insights into the continuing unfold of northern pike during Southcentral Alaska. A local species in Inner and Western Alaska, northern pike had been illegally offered to the Susitna River basin within the Fifties. Since then, the predatory fish has develop into established in additional than 150 lakes and rivers within the area.

Till now, the unfold of northern pike used to be considered restricted to freshwater corridors or unlawful introductions by means of folks.

“They are a freshwater fish, and it used to be idea that Prepare dinner Inlet represented a marine barrier preventing them from shifting from watershed to watershed,” mentioned Matthew Wooller, a professor on the UAF Faculty of Fisheries and Ocean Sciences and lead writer of the paper.

Wooller, who may be director of the Alaska Strong Isotope Facility at UAF, led the crew’s efforts to reconstruct the actions of pike by means of examining otoliths accrued by means of ADFG since 2019. The composition of strontium isotopes within the layers of an otolith can also be matched with chemical signatures in quite a lot of waterways, appearing the place a fish traveled throughout its lifestyles.

“Strontium varies in step with geology and placement,” Wooller mentioned. “If pike are shifting between watersheds, you’ll pick out it up by means of examining strontium within the otoliths.”

The learn about discovered 3 pike from 3 separate places with isotopic signatures matching higher Prepare dinner Inlet water, suggesting that they had occupied the inlet one day. The ones fish had been stuck in freshwater habitats that connect with Prepare dinner Inlet: Campbell Lake and Westchester Lagoon, each in Anchorage, and Vogel Lake at the Kenai Peninsula. The invention highlights the steep problem of restricting the unfold of northern pike within the area. It means that ocean-connected waterways the place northern pike were eliminated would possibly develop into reinvaded.

As environment friendly predators, pike affect local fish species akin to salmon after they invade new territory.

The newfound realization that the fish are shifting via estuaries “is solely another reason that northern pike are a poster kid of what makes an impressive invasive species,” mentioned Peter Westley, a UAF affiliate professor of fisheries who has studied northern pike of their local and offered levels for over a decade.

Whilst relating to, the brand new analysis additionally may just result in extra centered motion towards the invasive fish.

“Confirming northern pike can use this pathway gave us the tips we had to now focal point on combating this unfold and protective precious habitats,” mentioned Parker Bradley, an ADFG invasive species biologist.

Kristine Dunker, who coordinates an ADFG program to control invasive northern pike in Southcentral Alaska, mentioned “the findings will assist direct sources towards tracking spaces with out pike which are on the best chance of invasion.

“This discovery has been a step ahead, each scientifically with our figuring out of northern pike ecology in North The united states and likewise for our invasive northern pike control right here at house,” Dunker mentioned.

Together with Wooller, Bradley, Dunker and Westley, members to the paper incorporated Karen Spaleta at UAF and Robert Massengill, previously at ADFG.