Superior Fisheries

Highlights of Lake Superior fisheries management

No. 11 December 2002

Editor’s Note: Feel free to reproduce all or part of Superior Fisheries in your organization’s newsletters. We welcome your comments.

Chinook salmon update

The numbers of returning adults from this year’s chinook salmon run are in. The French River trap and seining operation caught a total of 106 individuals this fall. Of these, 66 fish were of the Lake Huron strain stocked in 1999-2002. These fish were stocked in an attempt to revitalize the Minnesota chinook program after declining returns to the French River of Minnesota strain fish made the program unsustainable. Criteria to evaluate this program include having enough fish return to enable spawning of 75 pairs of disease-free fish. This criterion will be applied in each year, 2003-2006. In 2002, the run size limited spawning to 27 pairs of fish. However, this was the first year Lake Huron strain fish were old enough to spawn. The next two years will give a better indication of the viability of this program, with two reproductive age year-classes expected to return in fall 2003 and 2004.

Knife River ground-water survey

Through a partial grant from the US Fish and Wildlife Service and matching support from the DNR, an aerial survey will be conducted to identify sources of ground water that provide important habitat for trout and salmon. Special technology including a thermographic sensor and several other cameras that record specific wavelengths of light will help flag areas of suspected ground water seepage. The aerial data gathering and outside ground-truthing fieldwork for this project will start early this winter. Identification of these resources should prove to be a valuable planning tool to focus restoration and habitat initiatives. We’ll keep you updated on the progress of this project as it gets underway.

Lake trout assessments

Each year, we conduct assessments of adult lake trout in May and juvenile lake trout in summer to monitor abundance and to assess the progress of restoration. Lake trout abundance has stabilized in recent years, and the proportion of wild fish has increased. In the May assessment, the abundance, measured as catch-per-effort (CPUE), was 39.9 fish per 1,000 meters of net, and was similar to abundances measured from 1996 to 1999, which ranged from 35.3 to 46.6 fish per 1,000 meters. In May more than 70% of the adults caught were wild fish, which is the second highest percentage in recent years. During the summer juvenile lake trout assessment, the CPUE of wild fish was 99.9 fish per 1,000 meters of net and 82% of the fish caught were wild fish. These are the highest values recorded since lake trout restoration began, and the continuing upward trend in wild lake trout abundance is encouraging.

New boat ramps and need to recognize fishing nets

Although there are only about 20 active commercial fishermen operating in the Minnesota waters of Lake Superior, there is potential for increased interaction with boat anglers. Anglers who are now using the new Taconite Harbor and Twin Points access sites may not be aware of local gillnet locations and markings. By law, gill nets must be marked by one orange or red flag on the lakeward or easterly end, and two flags, either orange or red over a second white flag on the shoreward, or westerly end of the net set.

Most locations where commercial gillnets are set are used year after year. Boat operators are urged to avoid crossing between flags, which may indicate a net or anchor line in place, which could tangle with your gear. Suspended nets can require up to a thousand feet of line between the net and anchor. These illustrations depict a typical float net and bottom net used by the commercial fishery in Minnesota waters of the lake.

Happy holidays from the Lake Superior Area Fisheries staff!