Lake Ontario fishery threatened by invasive species

[Spiel]

Lake Ontario fishery threatened by invasive species

 

 

March 14, 2008

Thomas J. Prohaska / buffalonews.com

 

 

LOCKPORT — Invasive species and fluctuating populations of game fish and their prey will continue to keep the Lake Ontario fishery in a state of flux, state officials said at a meeting here Thursday.

 

The Department of Environmental Conservation’s “State of Lake Ontario” session drew about 50 anglers and charter boaters to Cornell Cooperative Extension’s 4-H Training Center at the Niagara County Fairgrounds.

 

Robert O’Gorman, a field station supervisor for the U.S. Geological Survey, told the audience that populations of alewife and rainbow smelt in the lake have fallen to near-record low levels. Those species are among the favorite foods of trout and salmon.

 

“I can’t really give you a reason,” he said, although he speculated that the heavily stocked trout and salmon species used to bolster the fisheries are simply chowing down heavily on their favorite prey. He also said antipollution measures that sharply reduced the discharge of phosphorus into the lake decades ago may be hurting the alewife and smelt.

 

O’Gorman said that’s because phosphorus triggers the growth of plankton, which the alewife and smelt like to eat.

 

Dan Bishop, a DEC regional fisheries manager, reported that the average weight of the chinook salmon in the lake, a popular fish among anglers, is lower than a few years ago.

 

But Vince Pierleoni, owner of Thrillseeker Fishing Charters in Olcott, said that’s not all bad. He said his customers think the slimmed-down chinooks fight harder. “That’s the sport,” he said. “They have less fat. We think they’re more physically fit.”

 

But one thing his customers don’t like is lake trout with gashes in their sides caused by sea lampreys, a parasite fish that’s on the rise.

 

Dan Connerton of the DEC said the lake trout population has fallen by about 80 percent of its levels of 15 years ago, while the number of lamprey gashes in the lakers they’ve tested are on the rise. He said with the lake trout population crashing, lampreys are attacking other trout species and also going after salmon.

 

Pierleoni said lampreys like clean water, and the Great Lakes are getting cleaner all the time.

 

“There’s an international effort to restore lake trout across the Great Lakes,” said Jana Lantry, a DEC biologist. But she said first-year survival of stocked lakers has been “really poor” and no one knows for sure why that is. Pierleoni said lampreys like to eat freshly hatched lake trout.

 

Lantry said 453,000 baby lakers were stocked in Lake Ontario last year, and that number should rise this year.

 

O’Gorman said another alien invader has entered the lake in ballast water discharged by foreign merchant ships: the “bloody red shrimp.”

 

The quarter-inch crustacean has been found in large numbers in the stomachs of alewifes, perhaps meaning that they could make a food source for that key species. But O’Gorman said no one is quite sure what the shrimp are eating, and it might take a decade to figure out their overall impact.

 

“It’s a whole new lake, a whole new ecosystem, a whole new food web,” he said.