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Invasive Fish Found In Lost Island Lake

By Staff | Dec 6, 2011

RUTHVEN The efforts to clean up Lost Island Lake got some bad news last week when an invasive species of carp was discovered in the lake, located northwest of Ruthven. Officials of the Iowa Department of Natural Resources reported Silver Carp were found in the seine nets of commercial fishermen working on Lost Island last week.

DNR Fisheries Biologist Mike Hawkins says this is the third time this year that an invasive carp species has been found in lakes in northwest Iowa. Back in August, DNR personnel captured two bighead carp in East Lake Okoboji while conducting routine sampling and in September, a commercial fisherman caught both bighead and silver carp in Elk Lake, located south west of Ruthven.

The Bighead and Silver Carp are members of the Asian Carp family of carp, which are not native to Iowa lakes. The fish have recently invaded the Missouri and Mississippi Rivers, due to the extreme flooding in both rivers over the past summer, which allowed the foreign fish to travel past fish barriers located on the Little Sioux River.

Carp present challenges in a lake as they are bottom feeders that stir up the silt on the bottom while foraging for food, which in turns creates turbidity, or cloudy waters. Recent efforts by the DNR have included the draining of shallow lakes and marshes and the installation of fish barriers to prevent carp from moving from lake to lake. A fish barrier was completed earlier this year on the Blue Wing Marsh, east of Lost Island Lake, which drains into the lake.

For now, DNR fisheries personnel plan to continue to monitor Lost Island, Elk and East Lake Okoboji waters to assess the populations of the invasive carp to try and determine the impact they might have on the lakes. However, DNR fisheries biologists believe the invasive carp may not survive in the lakes, as they normally need a larger river system in order to reproduce, rather than a lake.

Much remains to be learned about these species; however it is unlikely that they will reproduce in lakes, since they require large river systems to successfully spawn.