The rusty crayfish (Orconectes rusticus) had completely invaded Star Lake, as well as many other lakes in the region. About 1990 I attended a DNR workshop about the rusty crayfish held in Boulder Junction. It was the first I had heard about the animal. It was a fairly pessimistic presentation, with a report that the DNR knew of no effective means of control. We were warned that the presence of rustys meant a loss of weeks in the lake, with obvious loss of good fishing, and the displacement of native crayfish.
My son and I sampled the lake around our dock and did, indeed, find rusty crayfish--in large numbers. They are easy to identify with a rusty spot about a half inch in diameter (in adults) about midway down the body. I estimate that then, about 1990, the ratio of rusty crayfish to natives was about ten to one. For at least the last ten years we have seen no natives, even though we trap or catch, in a typical year, several hundred crayfish to make crayfish creole (take any shrimp creole recipe and substitute crayfish tails for the shrimp).
Trapping was not seen to be a viable solution, as the trapping tended to remove fish after they had reproduced.
Ted Rulseh's article in the October, 2008, Wisconsin Natural Resources Magazine suggests that intensive trapping along with encouraging predator fish (smallmouth bass being suggested) can relieve the problem. However, that article, and others, suggest that lakes infested with rustys can expect long term, and significant, ecological change.
In Star Lake the reduction in weeds is very clear. An extensive weedbed that used to be in front of our property on the north bay of the lake is completely gone. We think we have seen a reduction in the level of crayfish recently, beginning in 2007. This would correspond to the loss of the offshore weedbed. Others on the lake have not reported a reduction in the crayfish.
**** indicates no known author.