The Judas Fish: Leading Invasives to Slaughter

Biologists have tried various ways to rid Western lakes of invading lake trout, such as electrocuting their eggs or encouraging anglers to take as many of the fish as they can catch. But on Montana’s Quartz Lake, Muhlfeld and his team worked with the National Park Service to deploy a weapon they believe will greatly improve the bull trout’s odds: the Judas fish.

The crews create these Judas fish by scooping up adult lake trout, cutting them open and inserting tracking devices. Then they sew the live fish shut and release them back into the lake.

In autumn, the crews spend weeks clustered around the woodstove in a cabin on Quartz Lake, heading out at night on the nearly frozen lake, listening through headphones for the ping of sonic telemetry to track the Judas fish.

It’s a 900-acre lake, yet over a two-week period around Halloween, all the adult lake trout gather at night at the fish equivalent of a giant singles bar, at the base of an avalanche chute where cobble and boulders provide safe havens for them to spawn.

The Judas fish, living up to its biblical namesake, betrays the exact position. That’s when the biologists drop the nets and pull them in, hand-over-hand to the slaughter.

LINK (via: Discover Magazine)

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