
The St. Mary’s River produces more sea lamprey than all Great Lakes tributaries combined.
By Howard Meyerson
Sault St. Marie, Ont. — Anglers on the St. Mary’s River may notice a change in water levels in the river’s rapids in June and July. An experimental sea lamprey trapping effort below the Brookfield Renewable Power Co. hydro-dam there requires higher flows at night when spawning lampreys are more active, said Great Lakes Fishery Commission staffers.
This is the second season of the experiment and the flow-change agreement between GLFC and the power company. Researchers say the river produces more lampreys than all other Great Lakes tributaries combined. The trapping experiment is testing net designs and the effectiveness of changing the dam’s flow regime.
“There are about 15,000 spawning sea lamprey in the river,” said Mike Siefkes, the GLFC sea lamprey program specialist. “We now capture about 4,700 lampreys at all the trap sites on the river. We get 3,500 at the power site.
“That’s about 23 percent of the river population and we are looking to improve our trapping efficiency and double that to 60 to 70 percent, closer to 9,500 to 10,000 lampreys.” Continue reading →