Pharos-Tribune

August 20, 2013

Biologists look to stop Asian carp

Biologists need help in curbing invasive species' progress into Great Lakes.


Pharos-Tribune

---- — BLOOMINGTON (AP) — Stop the invasion.

That’s the message biologists with the Indiana Department of Natural Resources hope anglers near Lake Monroe will heed.

The invasion they are concerned with involves several species of Asian carp that can now be found just below the dam at Lake Monroe. They are hoping people fishing in the tailwaters below the dam don’t help spread Asian carp into the lake. At this time, the biologists don’t think Asian carp have been introduced into Indiana’s largest man-made lake.

But they have had reports from some fishermen that some other anglers in the tailwater area have been catching live gizzard shad and then using them as bait in Lake Monroe, which fish can’t reach by themselves because the dam blocks them.

They also fear that some anglers may think they have caught gizzard shad but instead actually have silver carp, one of the species of Asian fish that have been spreading into Indiana rivers and streams, The Herald-Times reported.

“The tailwaters are a critical control point” in the fight to stop the spread of the Asian carp, according to Debra King, assistant fisheries biologist in Indiana’s District 5, which includes Lake Monroe.

“You can fish with live shad from [Lake] Monroe but you cannot transport them from anywhere else,” King explained. That includes the tailwater area that is actually part of Salt Creek, not Lake Monroe.

King said she first found Asian carp in the tailwaters area in 2010, while netting fish to see what species were available for area fishermen and women.

That was a surprise for the biologists, who had thought Williams Dam would be enough of a physical barrier to stop the spread of the Asian carp upstream and into the East Fork of the White River and its tributaries. But the area near Williams Dam flooded in 2008, allowing the fish to swim upstream unimpeded, eventually reaching the edge of Lake Monroe.

“We had thought the [Williams] dam would be big enough to stop them from getting into the East Fork,” said Doug Keller, aquatic habitat coordinator with the Indiana Department of Natural Resources.

Now silver and bighead carp, both invasive species of Asian carp, can be found all the way up to the dam at Lake Monroe.

If silver and bighead carp are introduced into Lake Monroe, most biologists believe the species will not be able to reproduce in great numbers because their native habitat is a river or stream. Even if that is true, the fish that do get into the lake will consume the microscopic plants and larva that desirable fish species, including crappie, bass and bluegill, eat. So, the best-case scenario would be that the carp would hinder the fish that have been stocked in Lake Monroe.

The worst-case scenario would be if the fish were to migrate upstream from the lake, where they’d be able to reproduce, allowing their eggs to hatch and populate the lake and other streams in greater numbers. If that happened, the carp would eat the food that sustains many desirable fish species.

“They could disrupt the lake in ways we don’t even think about,” King said. “They act differently when they’re not in their native habitat.”

The invasion would be expensive to try to contain and would be “impossible to control once they are in bodies of water that can’t be drained, like Monroe,” King said. “That’s why we want people to be vigilant” in keeping fish from other waters out of Lake Monroe, she explained.

Her recommendations included not dumping bait bucket water into Lake Monroe or any other body of water and disposing of leftover bait in a proper manner by placing them in the trash. Another request is to drain bait buckets before moving them to another body of water.

There are signs and posters near fishing areas that ask fishermen and women to also drain live wells and bilges on boats before leaving the lake or river. That’s because Asian carp eggs could be floating in the water in those areas.

King added that the live wells and bilges should be allowed to dry out completely before the boat is put into a different body of water. And, she said, checking for plants hitching a ride in and on boats should be something boaters do each time they leave the water.

Another problem that will develop if Asian carp get into Lake Monroe is they will hinder recreation on the lake. The most visible of the Asian fish are the silver carp, a species that will jump high out of the water when motorboats travel nearby. There are many videos on YouTube showing the fish jumping.

Since adult silver carp are “fairly commonly over 20 pounds,” they can injure boaters and water skiers, Keller said.

“We are seeing and hearing a lot of complaints in our infested rivers, the Wabash and the White,” he said. “It’s becoming a danger in our rivers,” adding that “it’s all going to be human mediated movement that will help (Asian carp) get into our reservoirs. They can’t swim into them.”

Keller said although the carp have a physical barrier keeping them out of the reservoirs, there are carp in some of the strip pits in the Greene-Sullivan State Forest area. The fish have traveled up ditches and when flood waters cause the water levels to rise, they swim into the strip pits.

Keller said once the invasive fish are in a body of water, there’s no way and no technology to get them out. That means the fish are now in the Ohio River system, up the White River and “knocking on the door of Indianapolis,” Keller said. One of the prized fishing rivers of Indiana, the Tippecanoe, is still clear of the fish in the upper region.

But vigilance of anglers and keeping barriers in place is the only hope of stopping the spread of the Asian carp.