Fish and Game out to kill pike before pike kill salmon

LAKE INVADERS

Posted: Sunday, October 15, 2006

 

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  Nelson motors the skiff to another net as Strait enters data about the day's catch. Photo by M. Scott Moon

Jerry Strait, a fisheries technician with the Alaska Department of Fish and Game, picks a small pike from a setnet on a small lake near Soldotna in the Soldotna Creek drainage. The department is working to rid area lakes of the predacious non-indigenous fish.

Photo by M. Scott Moon

Jerry Strait reserves a few weeks each year to fish two Kenai Peninsula lakes for one of the country’s most popular sport fish. In his pursuit of the fish, Strait is ruthless. He doesn’t care if it’s an adult or a juvenile, the size of his arm or the size of his pinkie, if it reaches his hands it’s a goner, and if he could he’d empty the two lakes entirely of the long-nosed sport fish, also known as the northern pike.

The two lakes where Strait gillnets for northern pike are part of the Soldotna Creek drainage where the invasive fish species has taken a strong hold, and in some areas decimated local fish populations.

On Monday, Strait, a fisheries technician for the Alaska Department of Fish and Game, and Jennifer Nelson, also a fisheries technician for the department, searched for northern pike as they slowly maneuvered a boat between each of the 12 gillnets set around the perimeter of a small lake in the Soldotna Creek drainage.

 

The size and number of pike have gone down significantly on some of the lakes where the Department of Fish and Game has setnets.

Photo by M. Scott Moon

Fish and Game is using the gillnets in an effort to control the northern pike, which if allowed to continue its spread from the Soldotna Creek drainage to the Kenai River and Moose River, could devastate populations of coho salmon, trout and other sport fish in the Kenai River drainage.

Northern pike are native to Interior and Western Alaska, but not the Kenai Peninsula where they have been illegally released and threaten native fish species, which have not had thousands of years to develop a balanced coexistence with the voracious predator.

The northern pike is so voracious in its eating habits that it often eliminates all other species of fish living in the lakes into which it is introduced.

 

Pike are eating machines that can do a lot of damage to indigenous species like coho salmon, Strait said. Lakes where pike normally live are deeper than the species likes to hunt so other fish can escape them, but shallow lakes where young coho live offer no refuge, he said.

Photo by M. Scott Moon

Most of the large lakes in the Soldotna Creek drainage and the small lake from which Strait and Nelson pulled fish Monday have suffered this sad fate.

“It only takes one bucket of fish and if the conditions are right, they take over,” Strait said.

Old-timers talk about all the rainbow trout and salmon that used to inhabit the lakes before they were replaced by northern pike, Strait said.

Fish and Game asked that the lake Nelson and Strait fished on Monday remain unnamed by request of the lake’s owner, who has allowed the department access to the lake in its effort to control northern pike. The lake concerns Fish and Game because it is one of three lakes that harbors northern pike and is directly linked to Soldotna Creek.

Like Fish and Game, the lake’s owners would also like to see the northern pike disappear from the lake.

“They’d love to see it go back to the way it used to be with rainbows,” Strait said.

 

Nelson motors the skiff to another net as Strait enters data about the day's catch.

Photo by M. Scott Moon

During the 15 days that Strait and Nelson gillnetted the lake in the spring and 10 days they had so far gillnetted the lake this fall, they caught nothing but northern pike.

So it was with surprise that Strait untangled a juvenile coho salmon from one of the gillnets on Monday.

Nelson, who manned the motor at the back of the boat, craned her neck to see the unusual find, as Strait freed the deceased fish from the gillnet and dropped it into a green tub alongside a handful of northern pike.

Rather than taking the juvenile coho as a sign of the lake’s recovery, however, Strait guessed the approximately three-inch fish probably entered the lake over a beaver dam separating the lake from a creek.

“We’ve had so much rain that it probably allowed the coho to swim past the beaver dam,” he said.

But compared to when Fish and Game seriously began control netting the lake in 2004, the number of northern pike caught in the lake has dropped sharply, said Strait, who has participated in a control netting project targeting two Soldotna Creek drainage lakes since 2002.

 

Jennifer Nelson and Jerry Strait work from a small skiff to pull pike from setnets on a lake near Soldotna in the Soldotna Creek drainage.

Photo by M. Scott Moon

“When we first came here there were a lot more pike,” he said.

As he pulled an empty gillnet out of the water, Strait said he once remembered finding more than 36 northern pike in the same net.

After 15 days of gillnetting this spring, Strait and Nelson caught 0.02 fish per netting hour, compared to 0.14 fish per netting hour in the spring of 2004. In other words, they caught 7 times as many fish per netting hour in the lake in the spring of 2004 as they did this spring.

In Sevena Lake, the second lake that has been targeted in the control netting project, gillnetting has reduced the northern pike population to the point where native fish appear to have made a comeback.

“We made a big impact in Sevena,” Strait said. “We made room for a lot of other species.”

Dolly Varden trout, coho and rainbows have appeared in Sevena Lake in growing numbers as the number of northern pike have declined. In response, Fish and Game stopped gillnetting two weeks short of completing a three week plan to gillnet the lake this fall. Fish and Game pulled the nets early to avoid killing rebounding native fish and because the number of northern pike being caught in the lake had dwindled.

On their last day of netting Sevena Lake, Strait said he and Nelson caught just three northern pike.

But while control netting appears to have successfully reduced northern pike populations in these two lakes, control netting can never eliminate a lake’s northern pike problem, said Rob Massengill, a research biologist with the Fish and Game Division of Sport Fish.

“We know we’re not going to get rid of them, we’re just trying to knock their numbers down,” he said, referring to the control netting project.

By reducing northern pike numbers in the two lakes, Fish and Game hopes to reduce the chances of the fish spreading from the lakes to Soldotna Creek and from there to the Kenai River and Moose River drainage.

Of the eight large lakes in the Soldotna Creek drainage, seven are known to have northern pike. Of the lakes in the drainage containing northern pike, the two lakes targeted by the control netting project and Tree Lake are directly linked to Soldotna Creek, which flows into the Kenai River. The Moose River also flows into the Kenai River and is a primary source of concern.

Although stray northern pike have been found in the Kenai River and Moose River drainage, Fish and Game hopes to prevent a reproducing northern pike population from establishing itself in either of theses areas as they have in the Soldotna Creek drainage.

Northern pike prefer slow-moving, weedy water, so the chances of the fish establishing a reproducing population in the fast-flowing Kenai River are low. But biologists fret over what might happen should a reproducing population of northern pike find its way into the slow-moving, weedy Moose River.

“That’s our sitting duck,” Massengill said. “If the Kenai River were as slow as the Moose River we would probably have pike up to our eyeballs.”

Unfortunately, the preferred habitat of the northern pike is also the preferred habitat for rearing coho.

Each year 20 to 40 percent of the Kenai River drainage coho population rear in the Moose River drainage.

While Fish and Game tries slow the spread of northern pike and decimation of coho, trout and other native fish species with control netting, it is also collecting stream flow and water quality data to help the department determine what other options might work to control pike.

“There’s a full spectrum of tools out there to kill pike, but most of them really wouldn’t go over well here,” Massengill said.

Techniques used to knock out or control northern pike populations in other parts of the country include, bombing, draining, chemical treatments and control barriers.

To be chemically treated a lake must be land locked to prevent the chemicals from spilling into non-target waters. Only a small handful of northern pike lakes on the peninsula are landlocked and might be considered candidates for chemical treatment, such as Scout Lake and Arc Lake.

As for draining most of the peninsula’s pike lakes extend into marshy areas and would be difficult to empty. Massengill did not address the bombing option, but said control barriers may be the most viable option for controlling the spread of northern pike from many of the peninsula’s lakes.

Control barriers would be used to prohibit fish moment in and out of lakes harboring northern pike, reducing the chances of the fish spreading into new territory.

Whatever techniques are proposed to control northern pike populations, none will be adopted until all interested agencies and the public have had an opportunity to weigh in on the options, Massengill said.

Responding to the northern pike problem, like any invasive species problem, is costly, and while the people who have illegally released the fish into the peninsula’s waters likely did not have malicious intentions, the consequences of their actions have been grave, he said.

“They taste good and they’re fun to fish for,” he said. “But with some of the salmon species we have here they’re not going to be real compatible. And they’ve already done a tremendous amount of damage to our stocked lakes and to the Soldotna Creek drainage.”

Patrice Kohl can be reached at patrice.kohl@peninsulaclarion.com.



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