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Great Lakes Article:

Troubled waters for lake fish

Invaders thrive as trout stock plummets

By Misty Edgecomb
Democrat and Chronicle
Published March 9, 2006

— HENRIETTA — The complex web of interrelationships in Lake Ontario never fails to surprise, said state and federal fisheries biologists who held an annual "State of the Lake" meeting Wednesday night at Rochester Institute of Technology.

The declining population of native lake trout continues to be a concern, with numbers down 50 percent since last year and 71 percent since peak populations in the 1980s. And fishermen can expect particularly challenging seasons for lake trout over the next few years because the state's stocking program, which supplements naturally reproducing lake trout populations, suffered a blow this year.

A disease outbreak at the Allegheny Fish Hatchery in Pennsylvania killed the 500,000 lake trout destined for Lake Ontario, so little stocking will be available to help the natural population this year, said Bill Culligan, Great Lakes section head for the Department of Environmental Conservation.

To stop the spread of the infectious pancreatic necrosis, or IPN, more than 700,000 fish at the Warren, Pa., hatchery were destroyed last fall.

Only about 110,000 fish could be diverted from the Finger Lakes for stocking in Lake Ontario. The impact on lake trout populations could linger for several years. But because the stocked fish will come from a hatchery known for its quality, some of that effect will be muted, Culligan said.

"We're only going to have one-fifth as many fish, but we think they're going to survive twice as well," Culligan said.

Meanwhile, fisheries surveys reported mixed news on invasive species in the lake. The round goby, a small fish native to the Black and Caspian seas, seems to be thriving. The fish has infiltrated all the Great Lakes and was first discovered in Lake Ontario in 1998. Now it has moved into the Erie Canal and is expected to colonize inland waters.

"They're reaching critical mass. They're really going to start to take off in New York," said Robert O'Gorman, a U.S. Geological Survey scientist based in Oswego.

Initially, biologists feared that the bottom-dwelling fish would push out other, native minnows and wouldn't be an attractive prey for large game fish. But studies indicate that lake trout as well as bass and cormorants are feeding on the goby.

And worries that gobies would feed so heavily upon smallmouth bass eggs that populations would plunge haven't been realized, even in the most heavily infested areas, O'Gorman said.

"Our greatest fears are not going to come true, I think," he said.

Meanwhile sea lampreys, leech-like fish native to the Atlantic coast, may be causing more problems as Great Lakes invaders. Lampreys have long been a success story of invasive species control, but as more and more rivers are cleaned up, their available habitat is expanding, O'Gorman said.

"The whole food web has changed," O'Gorman said.

One holdout from the native Lake Ontario population mix, the deepwater sculpin, seems to be making a comeback. This year's trawl surveys counted 17 of the small bottom-dwelling fish, when only five were caught over the past seven surveys. It's believed that the sculpin, which was once an important food source for lake trout, all but disappeared in the 1960s, before scientific fisheries surveys existed.

"This year we literally hit the mother lode," O'Gorman said. "I think it says a lot about our ecosystem and its ability to recover from past abuses."

MEDGECOM@DemocratandChronicle.com

 

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