Pike prowl Scout Lake

Biologists worried about spread of invasive fish

Posted: Friday, October 21, 2005

 

  Two northern pike -- along with the contents of their stomaches -- caught in Scout Lake three weeks ago by the Alaska Department of Fish and Game are displayed outside the ADFG offices in Soldotna. Pike are an invasive species that biologists say pose a significant threat to the Kenai Peninsula's wild salmon and trout populations. Photo courtesy of the Alaska Dep

Two northern pike -- along with the contents of their stomaches -- caught in Scout Lake three weeks ago by the Alaska Department of Fish and Game are displayed outside the ADFG offices in Soldotna. Pike are an invasive species that biologists say pose a significant threat to the Kenai Peninsula's wild salmon and trout populations.

Photo courtesy of the Alaska Dep

Much to the chagrin of local biologists, slimy, sharp-toothed invaders have been discovered prowling the waters of Scout Lake near Sterling.

“We’ve found pike in Scout Lake,” said George Pappas, area management biologist for the Alaska Department of Fish and Game.

Northern pike are not native to the Kenai Peninsula, but have been discovered in a number of area lakes, most notably the Mackey Lakes system north of Soldotna.

Because they are ravenous predators, pike pose a major threat to the area’s salmon and trout populations and their spread is considered one of ADFG’s biggest concerns.

“The Kenai River and Swanson River systems are out main concerns,” Pappas said.

If pike are able to get into those waters, he said it could spell disaster for salmon populations, especially coho, which thrive in slow-moving water.

“Coho fry like weedy, marshy waters,” he said. “Pike like weedy, marshy waters.”

Biologist Patti Berkhahn first discovered the pike in Scout Lake while conducting a netting project to determine the health of the lake’s rainbow trout and landlocked coho salmon. Because the lake is stocked, the department tries to keep a close watch on the fish populations.

Two years ago, Berkhahn said the netting project indicated coho stocks were strong.

“Last time there was lots of coho,” she said.

Three weeks ago, the results were shocking.

“When we went out three weeks ago, the nets went in the same place and we caught two little coho,” she said.

Biologists also caught some big pike, the largest weighing 12 pounds.

In lakes near the Mackey Lakes — where pike are believed to have been introduced in the 1960s — pike can spread through creeks or during high water events. But because Scout Lake is landlocked, its almost certain that the pike were transported there by humans.

“Bucket biologists we call them,” Berkhahn said.

It’s a misdemeanor to transport live fish without a permit in Alaska, and biologists would love to someday catch whoever is responsible for bringing the pike to the lake.

“Leave the stocking to us,” Berkhahn said.

The future of Scout Lake is unclear. Because the pike are now in control of the ecosystem, it’s unlikely ADFG will continue to stock the lake.

“We’re not in the business of feeding pike,” Pappas said.

One option for the lake is to use rotenone, a poison that cuts off the oxygen supply to fish in the lake. But its use is currently banned in Alaska, leaving few options for biologists to save a lake that has in the past served as a popular sport fishery for area anglers — especially young ones.

“One of the heavily impacted users are the kids who can’t go out on the rivers to go fishing,” Pappas said.

Berkhahn said that if the pike are allowed to stay in the lake, it’s unlikely they’ll become a popular sport fish because once they eat all the other fish in a system, their growth becomes stunted and they end up being uniformly small.

Biologists would like to act now to destroy the pike in Scout Lake before they become a source for another “bucket biologist” to move them elsewhere on the peninsula.

“If you leave it alone, you leave it as a source for the problem to continue to spread,” Pappas said.

It’s now up to the public to decide what will happen. Because funding is scarce and there’s a moratorium on using rotenone, he said it will take a public outcry to get the problem resolved.

“What does the public want will help us determine what direction we’re going to go in,” he said.

For his part, he recommended that the public make a stand against the pike sooner rather than later.

“It would behoove us to act aggressively now,” he said. “Imagine the reduction in salmon production on the Kenai River if this spreads there.”



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