Swimmer’s Itch Study in Leelanau County
Lakes, Maddie Messner, Oakland University April 21
GLA Guardian Seminar: Tree Planting Workshop May 14
11 a.m.-noon, The Leelanau School
Presented in conjunction with the Leelanau
Leelanau Conservancy Annual Native Plant Sale May 27, 28
* Visit our calendar page for details on these events and others, including time and place.
To assist the Glen Lake Community in restoring their properties, The GLA will be sponsoring two seminars:
SEMINAR 1: Arbor Day workshop-Learn, Plan, and Execute
Please make plans to join an informative panel discussion on succinct next steps you can take to plant your property with trees, shrubs and groundcover. We will focus on “take-aways”. Following moderated presentations by the Leelanau County Conservation District, a Forester and a Landscaper, there will be a robust question and answer period. We will then continue discussions over a casual lunch, courtesy of a generous sponsor. Following lunch, we will adjourn to the school gymnasium for an opportunity to visit vendors that are able to supply the products and services needed to accelerate the natural growth on your land. Free tree saplings will be available from the Leelanau Conservation District.
When: Friday, April 29, Leelanau Schools Karman Activity Center (1 Old Homestead Rd, Glen Arbor)
Times: 10:30-Noon Panel Discussion; Noon-2:00 PM Lunch and Vendor Tour
Co-sponsor: “Re-Arbor Glen Arbor” Task Force
Seminar 2: Tree Planting Workshop
GLA also plans to co-sponsor (with the Leelanau Conservation District) a “hands on” tree-planting workshop on Saturday, May 14, at a site to be determined. Please mark this date on your calendar. Free tree saplings will also be available. Details on this seminar with be available on the GLA web site calendar and an email blast sent to the membership. It will also be advertised in the Leelanau County Enterprise.
WHERE HAVE WE BEEN?
The Glen Lake Association (GLA) has a 30-plus year effort in the research and control of swimmer’s itch. Our research in the mid 80’s helped define the life cycle of swimmer’s itch on Glen Lake, i.e., one snail species and one bird species.
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. 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. We have the longest working relationship with SICON, Inc., the world leader in swimmer’s itch research, education and control.
WHERE ARE WE NOW?
Common 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. 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. From 2010 to present, GLA’s approach was “limited” to recommending topical creams (“Itch Guard”), swimmer education, and Common Merganser harassment. 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.
WHERE ARE WE HEADED?
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. However, we are concerned that our current harassment strategy could be losing its effectiveness. 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. Conducting this research on Glen Lake will drastically mitigate the risk posed by more common mergansers on our lake.
Cercarial larva is the parasite that causes swimmer’s itch on Glen Lake. (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).
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. 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). This WAS the only treatment for 30+ years from the 50’s to 80’s. After MUCH debate, GLA conducted three years of research (with SICON’s founder) in the mid-80’s. 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.
With GLA’s inability to obtain highly restricted trapping permits, we were relegated to a HARRASSMENT STRATEGY from 2010 to the present. 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. 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.
Given Common Merganser counts are increasing despite increased harassment, we believe the risk of swimmer’s itch on Glen Lake could be increasing. Other lakes in Northern Michigan, such as Higgins Lake, that have not had a strong deterrent history like Glen Lake, have witnessed dramatic problems. 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.