That is why we are participating in a coalition of 14 other lakes to seek the necessary funds to support research and control efforts, ideally on Glen Lake. Other lakes in Northern Michigan, such as Higgins Lake, that have not had a strong deterrent history like Glen Lake, have witnessed dramatic problems. Given Common Merganser counts are increasing despite increased harassment, we believe the risk of swimmer’s itch on Glen Lake could be increasing. However, last summer, the brood number increased to three and each brood had a higher number of young bringing the new resident Common Merganser population to a total of 30, compared to nine in the prior year. Our only metric to measure effectiveness has been brood/bird count, and we have been able to keep the number of broods between one and two per summer. With GLA’s inability to obtain highly restricted trapping permits, we were relegated to a HARRASSMENT STRATEGY from 2010 to the present. After three years of fecal analysis of a wide variety of bird species on Glen Lake, the Common Merganser was identified as the primary bird host and constituted the vast majority of swimmer’s itch cases. After MUCH debate, GLA conducted three years of research (with SICON’s founder) in the mid-80’s. This WAS the only treatment for 30+ years from the 50’s to 80’s. Historically, we tried to kill the snails by copper sulfate treatment, but that was ineffective (snails repopulated after expiration of the two hours of chemical potency). The key to success in our treatment of swimmer’s itch is to BREAK THE LIFECYCLE of the parasite in one of the two hosts. (NOTE: there are nine species of parasites that cause swimmer’s itch in Michigan.) Cercariae are shed by Stagnicolous snails that are infected by parasites transmitted by avian hosts, the common Merganser in our case (presently). Conducting this research on Glen Lake will drastically mitigate the risk posed by more common mergansers on our lake.Ĭercarial larva is the parasite that causes swimmers itch on Glen Lake. Consequently, we are working with a state coalition of 15 lake associations and Sicon (now back in business) to find the dollars to support the research required by the state before it will lift the moratorium on trapping mergansers. However, we are concerned that our current harassment strategy could be losing its effectiveness. We feel that we have been fortunate to date, especially in comparison to other neighboring lakes, having benefited from all the diligent time, energy and money ($350,000) invested over the last two decades. The harassment was aimed at reducing the number of broods coming on the lake in the summer along with preventing bird loafing on any particular shoreline. From 2010 to present, GLA’s approach was “limited” to recommending topical creams (“Itch Guard”), swimmer education, and Common Merganser harassment. Part of the reason was SICON, LLC went temporarily out of business and the permits were denied pending further research, thus interrupting our control strategy using SICON as our strategic partner.
We have the longest working relationship with SICON, Inc., the world leader in swimmer’s itch research, education and control.Ĭommon Mergansers are a federally protected migratory species (US Fish and Wildlife Service), and a moratorium was placed on trapping and relocating broods on Glen Lake from 2009 to present. We were also the first lake association to obtain a major grant ($200k) from the State of Michigan Department of Commerce (mid-80’s) to support these programs. GLA was one of the first lake associations in the nation to live trap and relocate Merganser broods (two campaigns spanning ten years) with the help of SICON, LLC which was able to obtain the necessary state and federal permits. Our research in the mid 80’s helped define the life cycle of swimmers itch on Glen Lake, i.e., one snail species and one bird species. The Glen Lake Association (GLA) has a 30-plus year effort in the research and control of swimmer’s itch. History of Glen Lake’s Swimmer’s Itch Management Programs What it means to be a Glen Lake Guardian.Glen Lake Association 2015 annual meeting.Assistance in Becoming a Glen Lake Guardian.
Fisheries, Wildlife, Recreation & Water Safety.
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