Taser-like device used on Lake Okabena to shock fish, count carp
WORTHINGTON -- With temperatures a few degrees warmer than freezing Tuesday morning, a biologist and water resource scientist launched a boat with some rather strange-looking contraptions and set out along Lake Okabena's shoreline on a quest to f...
WORTHINGTON - With temperatures a few degrees warmer than freezing Tuesday morning, a biologist and water resource scientist launched a boat with some rather strange-looking contraptions and set out along Lake Okabena’s shoreline on a quest to find carp.
Tom Langer and Jeff Strom work for Wenck Associates, a Minnesota-based engineering and consulting firm hired by the Okabena-Ocheda Watershed District (OOWD) to conduct a study of carp populations in the local lake. The results are anticipated in the next few weeks, and will provide guidance to the agency as it continues to address water quality concerns in the watershed.
Equipped with a standard shocking boat - two booms extending from the bow with dangling anodes to emit an electric charge - the men transected the lake. The anodes provided enough zap to temporarily shock the fish, causing them to float to the surface within four to five feet of the boat.
“It’s a taser for fish,” described Langer.
The fish are naturally attracted to the current, he explained. When they get close enough to realize what’s happening, they are temporarily stunned.
To accurately measure the density of carp in the lake, the men netted all of the carp that came to the surface, then weighed and measured them.
Langer said a carp density of 88 pounds per acre is considered to have a negative impact on water quality. The rough fish stir up sediment and nutrients in a lake, which reduces vegetative growth and then, in turn, affects the fishery.
The Minnesota Department of Natural Resources has conducted trap and gill netting on Lake Okabena in the past to gather data on game and rough fish populations. OOWD Administrator Dan Livdahl said those surveys have always revealed a low population of carp in Lake Okabena compared to other lakes in southwest Minnesota.
People who use the lake, however, disagree with the DNR findings. It is possible for the rough fish, which are bottom feeders, to avoid the nets. Complaints about carp populations in Sunset Bay are typical, Livdahl said.
Without a boat landing to the bay, however, Langer and Strom were hopeful they would find the carp spread out within the lake. After an hours-long search, however, Langer said they didn’t see a lot of carp, though those they found were impressive in size. He anticipates the data will show the carp population is low enough in Lake Okabena that it doesn’t have a big impact on water quality.
In addition to recording carp numbers, Langer said they noted other fish species, such as sunfish, which are good at preying on carp eggs and helping to control the carp population.
The carp study is being funded by the watershed district’s survey and data acquisition fund, established with a special $50,000 levy in 2017.