Flying fish: A new threat to the Iowa Great Lakes?

2012-03-22T22:30:00Z 2013-12-17T10:59:41Z Flying fish: A new threat to the Iowa Great Lakes?By Russ Oechslin Journal Correspondent Sioux City Journal
March 22, 2012 10:30 pm  • 

OKOBOJI, Iowa -- Iowa Department of Natural Resources Fishing Management Biologist Mike Hawkins is hoping construction of an electric fish fence at or near the Lower Gar outlet will come in time to prevent an infiltration of the dreaded Asian silver carp into the Okoboji chain of lakes.

The flying or jumping silver carp and bighead carp are thought to have come upstream from the Missouri and Little Sioux rivers, and over the dam at Linn Grove during periods of high water.

The two species were introduced in the U.S. by Arkansas fish farmers who wanted to clear ponds of excessive vegetation. But when floods hit the area, the carp were able to enter local rivers and streams.

While the fast growing bighead carp consumes more food than the more desirable muskies and walleyes, destroying the natural ecology of the lakes, it is the silver carp that is more feared for the same reason and because the flying fish can jump 10 feet out of the lake water and injure swimmers and boaters.

Both the bighead and silver carp have been found in nearby Elk and Lost Island Lakes, in Clay and Emmet Counties. And a bighead has been netted in East Lake Okoboji.

Hawkins said he and DNR officials are "actually assuming the silver carp is here (in East and West Lakes) as well. We're hoping though not at a density to cause a problem. The point of barrier is to prevent that from happening and stay ahead of it."

While much of the biology involving the Asian species is unknown to North America and the Upper Midwest, Hawkins says the fish may not be able to reproduce well in still lake waters.

"But nobody knows that for sure," said former Okoboji Protective Association president Phil Petersen. "There are a number of streams, like The Harbor and canals that are almost like a river, places they could breed here."

The Asian species are hard to catch because they don't bite on a hook and bait. The only way to get them is by net. And they tend to jump over a net.

Even short of breeding, the Asian carp's 15-20 year lifespan is enough to cause a problem with the ecology, Petersen added. "And after that time, even if they couldn't breed here, there could be a new supply of them."

"The chance of us having an event like we did that allowed the carp to come in was small," Hawkins explained this week. "A lot of things had to come together. And they did."

The biggest barrier to building the electric fish fence, viewed as the only preventative measure, is the estimated $700,000 cost. The DNR projects that figure after considering the Heron Lake, Minn., fence built 20 years ago and taking inflation into consideration.

Petersen and banker Neal Conover created and became co-chairs of the "Fish Barrier Fund," and have already raised more than $550,000 from area individuals, groups, and the Department of Natural Resources. The Dickinson County Board of Supervisors pledged $50,000 Tuesday.

Petersen and Conover are also seeking an appropriation from the state legislature, but admit they hold little hope of seeing that happen, even after the Iowa Senate passed a bill with an amendment to that end earlier in the week.

Another barrier is the time frame. Construction would be best done now while water levels are low. It will be difficult to begin construction until after summer has passed.

Hawkins termed the situation "a giant game of catch-up."

"The situation is forcing our hand into these extraordinary measures to make sure we don't end up with something we'll regret later on," Hawkins said. "I wish we didn't have to put up a fish barrier that costs maybe $700,000. But can we afford not to? That's the question and realization a lot of community members have some to. We can't really afford the risk."

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