News & Features

State Biologists Discover Walleye in Swan Lake

Officials investigating the case say the two walleye caught are evidence of an illegal introduction

Biologists reported catching two walleye in Swan Lake last week during a gill-net operation, marking the first time the species has been discovered in the lake and raising concerns about the illegal introduction of yet another non-native fish in Montana’s waters, according to Mark Deleray, Region One fisheries manager for Montana Fish, Wildlife and Parks.

Deleray said it’s highly likely the fish originated from an illegal introduction, a trend that has wreaked havoc on hundreds of water bodies across the state, costing hundreds of thousands of dollars to rectify.

In most cases, the illegal introduction cannot be undone, often leading to lost recreational fishing opportunities, as well as collapsing ecosystems and altered food webs.

The recent case is problematic because walleye are highly predacious and could impact the native bull trout population, as well as the kokanee salmon fishery in Swan Lake, Deleray said.

The two walleye each measured 17 inches long. Officials don’t know how long the fish had been in the lake.

State law says it is illegal to introduce or transplant fish in Montana unless authorized by the Fish and Wildlife Commission. The release of any live fish into any Montana pond, lake, stream, or river without FWP authorization is strictly forbidden. Penalties can range from fines of $2,000 to $10,000, loss of fishing, hunting, and trapping privileges, plus liability for the costs to eliminate or mitigate the effects of the violation. Anglers cannot move any live fish from the water in which the fish are caught.

Last year the Fish and Wildlife Commission took action to strengthen FWP’s response to illegal species introductions. FWP will now launch an investigation to confirm the presence and distribution of the introduced species within 30 days, and formulate a plan for responding to, and potentially suppressing or removing, the illegally introduced fish.

The actions are part of the response outlined in the new commission policy.

Deleray asked anyone with information on who introduced walleye into Swan Lake to call 1-800-TIP MONT.

Callers do not need to identify themselves and may be eligible for a cash reward of over $15,000.

Anglers are encouraged to keep any walleye caught and report additional sightings of walleye to FWP at 752-5501.