Lamprey numbers increasing

[Spiel]

Lamprey numbers increasing

LAMPREY: Local creeks part of program

 

Monday April 28, 2008

Jeff Helsdon / Tillsonburg News

 

 

The Ministry of Natural Resources is ramping up its fight against the sea lamprey in Lake Erie.

Population estimates for the invasive species in Lake Erie now sit at 16,000. Lampreys attach themselves to fish and feed on the host’s bodily fluids, often resulting in wounding or death. It’s believed lamprey made their way into Lake Erie in 1921 when the Welland Canal was deepened.

Chemical controls, called lampreyicides, have kept numbers in check, but treatment to Lake Erie streams is done on a three to four-year cycle. In addition, other measures are in place such as an inflatable lamprey barrier on Big Creek.

 

Researchers aren’t sure why lamprey numbers in Lake Erie are so high. The target is to keep the breeding population to between 2,000 and 6,000. Lampreys are present in the other Great Lakes, but similar spikes in the population didn’t occur elsewhere.

 

Fraser Neave, a larval assessment biologist with the Department of Fisheries and Oceans, said researchers aren’t sure why the numbers are up.

 

"If we focus our efforts over the next couple of years we should get the numbers under control," he said.

 

Plans to ramp up lamprey treatment include treating all lamprey-producing streams on both sides of Lake Erie in both 2008 and 2009. Locally, Big Creek and the Big Otter Creek are part of the list. In addition, trapping will take place on Big Creek to evaluate lamprey spawning success.

Lamprey abundance is a roadblock to the present lake trout recovery efforts. Although Lake Erie has a decent population of rainbow trout and other salmonoids, lake trout are the preferred host for lamprey. Lake trout are favoured hosts for two reasons - because the fish reach the large size lamprey like and because of their behaviour.

 

"Where they are in the water column (depth they live at) makes them particularly vulnerable to lamprey," Neave said.

 

Erie’s lake trout populations have been based on fish stocked on the U.S. side. Ontario’s goal in its lake trout stocking efforts is to put 50,000 fish per year in the lake for three years to establish a genetically diverse self-sustaining population.

 

"We’re facing a situation where we don’t have any native lake trout in Lake Erie," said John Copper, Ministry of Natural Resources information officer with the Lake Erie unit. "We’re trying different varieties (of lake trout) to see which is best."

 

Previous Ontario lake trout stocking efforts were unsuccessful, but it was felt the fish were released too close to shore. The plan this time is emulate the American practice of releasing the fish over deep-water shoals.

 

Preliminary work assessing the shoals on the Canadian side of Lake Erie will take place later this year prior to the stocking. Some of the shoals being considered include the Nanticoke Shoal, Tecumseh Reef at the mouth of the Grand River and a shoal off Peacock Point.

MNR researchers are also evaluating various lake trout species. One of the characteristics being sought is to find a variety that will spawn once before the fish reach the size targeted by lamprey.