Arctic Science Journeys
Radio Script
1997

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Alaska's Pillaging Pike
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STORY: Dozens of rivers with Indian names like Deshka and Yetna, as well as hundreds of lakes, make up Alaska's Susitna River watershed just north of Anchorage. Anglers once came from all over the world to catch lunker rainbow trout and king salmon. But that was 40 years ago.

Today, the salmon are still there, but the rainbow trout, as well as trophy size grayling and other native species, are all but gone. What happened to them can be explained in just two words--northern pike. Dave Rutz is a biologist with the Alaska Department of Fish and Game who manages the Susitna's fisheries.

RUTZ: "The northern pike is a predator and it pretty much eats everything that moves. Looking at stomach contents, I found a variety of species of fish inside of them, as well as mice, ducks, pieces of wood. Anything that floats they tend to attack."

And that's the problem. Rutz says pike in the Susitna river, its lakes and tributaries, are decimating native fish species. How they got there in the first place is a bit of a mystery, since pike are not native to southcentral Alaska. He says sport fishermen likely transplanted them in the 1950s from lakes elsewhere in the state. Although the Susitna watershed itself is huge, about the size of Indiana, Rutz says it was only a matter of time before pike wiped out native fish.

RUTZ: "They've really changed the population structure in a lot of the systems flowing into the Susitna. In the shallow lakes, and in those slow-moving tributaries, there are several that have been completely wiped out. The only thing they feed on now is themselves. They are real cannibalistic."

California biologists were recently confronted with a similar problem when someone released northern pike into one of that state's lakes. Officials there responded with a biodegradable poison called Rotenone that killed every fish in the lake. Officials plan to restock the lake with native trout and salmon. Poison wouldn't work in the Susitna River. Dave Rutz.

RUTZ: "We're not even thinking about that. We have a lot of real productive streams that are the driving force of this system. In order to wipe out northern pike you'd wipe out every salmon stream in the whole valley. And you probably still wouldn't get to the northern pike."

So to combat the pike, biologists in Alaska have lengthened the fishing season and eliminated catch limits. But Rutz says fishing alone isn't going to keep pike in check. He says people have to stop transplanting pike into places they don't belong.

OUTRO: For Arctic Science Journeys Radio, this is Robert Hannon reporting from Fairbanks, Alaska.