News

10 Jul

Swimmer’s Itch Control Update

Education, News No Response

Thank you to everyone who’s reported Swimmer’s Itch cases online as well as Common Merganser brood sightings–we’ve been monitoring reports and taking action on getting the broods off the lake.

The summer of 2018 is proving to be a challenging year for Swimmer’s Itch control for these reasons:

  • Winter conditions into April delayed merganser broods coming on the lake by three weeks, therefore live trapping was delayed also. Normally, all live trapping is completed by the first week in July. 
  • As trapping requires quiet conditions– no boat traffic, dogs in the water, people on docks/human activity around the trapping area–the weather related delay to trapping now makes for difficult conditions with more activity on the water.
  • This summer’s significant heat wave has resulted in an increase to the number of swimming hours on the lake.
  • Despite having relocated all 99 mergansers off the lake last year, we cannot eradicate Swimmer’s Itch, though it is at a reduced level. We continue to research what other life cycle(s) may be at work that have nothing to do with mergansers, though we still believe that the itch-causing parasite is largely cycling through Common Mergansers. This summer’s research will hopefully confirm this fact.

Lastly, a newly hatched merganser chick must be at least four weeks old before they can infect our snails with Swimmer’s Itch. Considering that, please know that seeing a brood on the lake for several days after reporting is not contributing to the itch problem.

Trapping Results

  • Seven broods of mergansers were live trapped and moved off the lake; this represents 54 individual mergansers. 
  • At least four more broods on Glen Lake need to be trapped and all effort will be made to relocate all the broods in the coming weeks. 
  • Our goal is, and always has been, to live trap and relocate 100% of the merganser broods.  

Finally, we resourced our trapping crew and equipment based on last year’s merganser brood count for three lakes – Glen, Lake Leelanau, and Lime. At the end of this year’s trapping season, we will evaluate the results. If the brood numbers are roughly the same as last year for all three lakes, we will continue our plan to share our resources as we are today.

How to Avoid the Itch

  • If possible, swim only in deep water and avoid swimming in the shallows. 
  • Swim in the later hours of the day as opposed to swimming in the morning or early afternoon. Last year’s research on “time of day” revealed the itch can be at a high level in the morning
  • Last year’s research revealed that Swimmer’s Itch is less intense in the later weeks of summer as opposed to the early weeks. 

If you do get a case of Swimmer’s Itch, remember–it is not a dangerous disease and using a topical cream with cortisone will bring relief from itching.

Please continue to report your swimmer’s itch cases at www.glenlakeassociation.org.  Thank you!

Respectfully,

Rob Karner, M.S.

Watershed Biologist


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