Biologists will study lake trout population

By MIKE RICHESON

Bigfork Eagle

This fall, biologists will sample fish in Swan Lake to determine how many lake trout have invaded the lake. Anglers first began noticing lake trout in the Swan in 1998, and evidence is mounting that the population is growing rapidly.

The lake trout is a non-native fish for Swan Lake, and its presence threatens the bull trout and kokanee fishery in the lake. Swan Lake is one of the few places in the nation where anglers can keep one bull trout per day.

The fish sampling will take place over a three-week period in late September using large trap nets and short-set gill nets. Biologists will capture the fish alive, mark them and release them. Returns of marked fish will allow the experts to estimate the number and size distribution of lake trout. A select number of adult trout will also be radio-tagged to learn about fall spawning movements and locations.

To sample the fish, biologists will use up to three trap nets, deployed on the bottom in deep water. Long leads will steer fish into holding chambers in the trap nets and they will be checked daily. Biologists will also use gill nets that will be checked regularly to reduce fish injury. The goal of the sampling is to capture, mark, and release alive as many lake trout as possible, so that a population estimate can be achieved. Boaters and others should watch for marker buoys and avoid the trapping areas, which will be rotating around the lake. The boat ramp will be signed with information during this survey.

The lake trout study on Swan Lake is being conducted through a collaborative interagency effort under a collection permit issued by Montana Fish, Wildlife and Parks. This net sampling will be carried out by a contractor under the supervision of the U.S. Fish and Wildlife Service and data analysis will be conducted by the Montana Cooperative Fishery Research Unit from Montana State University. Cooperators include Montana Fish, Wildlife and Parks, the U. S. Fish and Wildlife Service, U.S. Forest Service and Bonneville Power Administration. The cooperators urge anglers to sharpen their skills at fish identification and to report any lake trout caught in Swan Lake to FWP at 752-5501.

Future meetings with Swan Lake residents and angler interest groups will be held to answer any questions about the project. Contact any of the named parties for more information if interested in scheduling a presentation. More information about the Swan Valley Bull Trout working Group and this project is available by clicking on "Swan Valley Bull Trout Working Group" information on the Montana Trout Unlimited Web site: www.montanatu.org.