Spiny Water Flea Found in Trout Lake

Sep 26, 2014

Vilas County’s Trout Lake has a new invasive species.  Spiny water fleas were found earlier this week by a fisherman who noticed them attached to his gear. 

Jake Walsh, PhD student at the UW Madison Center for Limnology, says the finding is significant because there aren’t many northern lakes that have the invasive. 

“Given how much Trout Lake means to Vilas County I would say it’s a huge deal.  Also that we found them here at a pretty high density I would say is a pretty big deal.”

Spiny water fleas eat zooplankton…which means less food for fish, and fewer organisms to eat algae.  In Madison’s Lake Mendota, Walsh says the fleas are thought to have given rise to murkier water. 

Walsh says boaters should take extra precautions when leaving Trout Lake.  He says boats and equipment should be clean and dry for at least 24 hours before being using in another lake, because spiny water fleas can be hard to detect. 

“When they get abundant in the water column, you’re picking them up and you don’t seem them like you see Eurasian water milfoil.  So it makes them tough to clean off your boat.  But also when they get really abundant in the late summer and fall, there’s just a lot of them to pick up.” 

Water flea eggs are also hardy and can survive for months in lake sediment that could be picked up by a boat anchor.

Walsh says it’s not clear how long the fleas have been in Trout Lake.

Walsh says the invasive shouldn’t interfere with any of the research projects going on at the Trout Lake Research Station...though researchers will be taking extra steps to prevent contamination of nearby lakes.