A killer is stalking the waters of Southcentral Alaska, lurking in the shadows and ambushing our wild salmon and trout! Many Southcentral lakes and streams are already empty of everything but the killer: northern pike. Soon many of our sportfishing opportunities may be gone.
This message is part of the northern pike awareness campaign the Kenai Fish and Wildlife Field Office (KFWFO) and the Alaska Department of Fish and Game (ADFG) will be promoting throughout the coming year. This outreach effort includes television and radio public service announcements, videos, newspaper articles, posters, brochures, and flyers.
Invasive northern pike are causing serious problems with native and stocked fish populations on the Kenai Peninsula. They have also severely damaged some salmon populations in the Susitna drainage and the Anchorage bowl. Northern pike are native to most of Alaska north and west of the Alaska Range where they are an important sport and subsistence fish, but they are not native to Southcentral Alaska. Northern pike do coexist with salmon and trout in much of their native range but even there they can still reduce fish populations, especially if the habitat is suitable for northern pike such as shallow, weedy, slow-moving water where they can hide and ambush prey. Northern pike prefer to feed on salmon and trout over other fish species and have even been known to prey on baby loons and ducks.
Some have speculated that the eggs of pike may stick to waterfowl or floatplanes causing new introductions. While this mechanism is remotely possible, if it were common, northern pike would have been in Kenai Peninsula lakes long before the 1970s and in lakes that are not accessible by vehicles. Future illegal introductions can hopefully be prevented with increased understanding that this action is both detrimental to native fish populations and has legal ramifications (considered a Class A misdemeanor).
Some lakes on the Kenai Peninsula that once supported populations of rainbow trout, Dolly Varden and juvenile salmon are now devoid of those species. Areas like the Moose River and Swanson River are highly vulnerable to invasive northern pike because of vast amount of suitable pike habitat present and abundant rearing salmon and trout found in both. Currently, KFWFO and the ADFG are working on a plan to remove invasive northern pike from Stormy Lake. Stormy Lake is linked to the Swanson River which supports popular coho salmon and trout fisheries that could be damaged should Stormy Lake northern pike establish themselves in the Swanson River.
As with all invasive species, there are no easy "fixes" to eliminate northern pike from a water body once it becomes established. The Alaska Department of Fish and Game have used netting and control barriers on several area lakes and streams to reduce pike populations. However, these are only short-term fixes because catching all the pike in a water body is nearly impossible.
Draining a lake is often highly impractical, so another way to control an invasive fish is through the application of chemicals. Rotenone, a natural plant derivative, has been used successfully in the United States since the 1930s. Rotenone is easily absorbed through the gills of fish and aquatic insects and renders them unable to use the oxygen absorbed in their blood. It does not affect non-gill breathing organisms such as mammals, birds or humans when applied in the concentrations used to eliminate northern pike. Rotenone quickly breaks down into non-lethal compounds and naturally degrades with warm temperatures and sunlight, allowing waters to be restocked or naturally repopulated by native species.
Continued adverse impacts to natural water environments, fisheries, and the economy on the Kenai Peninsula are certain if no actions are taken to control or eradicate northern pike populations. With continued efforts, we believe that removing or containing northern pike on the Kenai Peninsula is an attainable goal.
These goals can only be accomplished with the cooperation of the public. You can help by not transporting any northern pike into lakes or streams on the Kenai Peninsula, and if you catch any, keep and report them. The Kenai River Sportfishing Association and the Kenai River Professional Guide Association are offering a $5,000 reward for information leading to the conviction of someone introducing northern pike into Kenai Peninsula water bodies.
To report illegal activity, call the Alaska Department of Fish and Game Invasive Species Hotline at 877-468-2748. For more information on invasive northern pike in Alaska, please visit the Alaska Department of Fish and Game website at: http://invasive.adfg.alaska.gov.
Cheryl Anderson is a Fish and Wildlife Biologist with the Kenai Fish & Wildlife Field Office, 907-262-9863. Check their website at http://alaska.fws.gov/ or Facebook page at http://www.facebook.com/pages/USFWS_Region-7-Fisheries-and-Habitat/180349382004304.
Previous Refuge Notebook articles can be viewed on the refuge website at http://kenai.fws.gov/. You can check on new bird arrivals or report your bird sighting on the Kenai National Wildlife Refuge Birding Hotline at 907-262-2300.