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Great Lakes Article:

Fishhook water flea appears in Lake Erie

By John Bartlett
GoErie.com- Times News
Posted 09/20/2002


Bob Wellington was fishing for walleye about eight miles northeast of Gull Point on Aug. 31 when he thought he got lucky.

The drag was heavy as he reeled in what he thought must be a big fish. Soon he noticed what looked like sheets of paper hanging from his fishing line, and his rod eyelets were clogged.

It wasn't paper, though. It was thousands of fishhook water fleas linked together — the first confirmed sighting of the invasive species of water fleas in local Lake Erie waters.

Wellington took several samples to confirm his initial identification, which proved correct.

Wellington's fish got away as he struggled with his line and the globs of fishhook water fleas hanging from it.

"I decided right then I didn't like them," said Wellington, an aquatic biologist with the Erie County Department of Health. "I knew they could be a real nuisance, but they were much worse than I expected. They are worse than the spiny water flea by 10 times at least."

The fishhook water flea is native to Eastern Europe, and first reached the Great Lakes in 1998 when it was first discovered in Lake Ontario, presumably having hitched a ride in the ballast water of an ocean-going ship.

It was found in Lake Michigan a year later.

It reached Lake Erie in 2001 when Igor Grigorovich, an exotic species researcher at the University of Windsor, Ontario, Canada, found it in the lake's western basin near the outflow of the Detroit River.

The fishhook water fleas' spread throughout the Great Lakes was expected, said Rochelle Sturtevant of Michigan Sea Grant. She set up in early 2001 a monitoring program to track the spread, location and population densities of the fishhook water flea and its cousin, the spiny water flea, which entered the Great Lakes in the 1980s and soon became well-established.

"(The fishhook water flea) is clearly expanding its range in Lake Erie and the other lakes, but the reports have been sporadic and the locations scattered," Sturtevant said.

Both the fishhook water flea and the spiny water flea are about a centimeter long. A loop, or hook, on the end of its long spiny tail that makes up about 80 percent of its total length distinguishes the fishhook water flea. The barbed-tail of the spiny water flea is without a hook. The barbs and hooks on the tails catch, pulling the tiny creatures into large blobs or sheets and enabling them to attach to fishing lines.

Fishhook water fleas — Cercopagis pengoi — and the spiny water flea — Bythotrephes cedestroemi — are zooplankton, the group of tiny animals that help anchor the food chain, said Chuck Murray, a Pennsylvania Fish and Boat Commission fishery biologist.

Among the problems posed by the two invasive species is their potential to displace native species and disrupt the food chain. They feed on other tiny species and compete with natives to become the dominant species, Murray said.

Some researchers are also concerned that the two invasive species are not as nutritious as the native water fleas and other tiny animals they are displacing. There are also reports that small fish have trouble consuming them or don't digest them well, Murray said.

Then there are the issues anglers have with them.

"I had a pretty decent fish on my line when I got tangled up with them," Wellington said. "I know that sounds like a fishy story about the big one that got away, but the fishhook water fleas are a real pain."
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