Lamprey control a multi-pronged effort
The Great Lakes and its fisheries were changed forever when sea lamprey gained access to lakes.
Sea lamprey are native to the northern Atlantic Ocean and its tributaries. The completion of the Welland Canal in the early 1900s allowed the lamprey past Niagara Falls and into Lakes Erie, Michigan, Huron and Superior. The native fish in these lakes, which did not evolve with the new predator, were devastated.
Lamprey feed by using their sucker-like mouth and latching onto the side of fish. The lamprey then feeds on the fish by sucking the blood of the fish through the circular spot created by its teeth. If the fish survives the attack, it is left with an open circular wound, which can get infected and eventually cause death.
The Great Lakes Fisheries Commission was formed in 1954 as an agency for the United States and Canada to work together for fisheries management and sea lamprey control. The two countries tried previously to work together on fisheries in the Great Lakes but it took sea lamprey to finally cause it to occur.
Over the years much research has gone into lamprey management and new technologies have evolved. Lampricide, a chemical that was found to control lamprey but not have huge impacts on native fish, is one control method that is used.
A yellow dye is added to the lampricide to make humans aware of its presence. Farmers are advised to turn off their irrigation systems when the lampricide is used during the nine to 12 hours of the treatment and to leave it off for 24 hours afterwards. Lampricide can have an impact on some broad-leafed plants. It does not bioaccumulate in the environment.
Lampricide isn’t the only control method. Near County Road 1, an inflatable dam is used to stop lamprey passage on Big Creek, reaching heights of up to two feet.
Gary Caron, a retired conservation officer who started in Simcoe in 1981, works on a contract basis controlling lamprey numbers at the dam. Next to the dam is a fishway with two cages that allows water flow to continue. Lamprey and fish are attracted to the flow and captured in the cage.
“They can jump quite a ways but they can’t jump that high,” he said.
Caron’s job is to check the cage daily in the spring when the lamprey are running up the creek. He also has to clean the debris out of the cage.
“They used to contact me if they need someone to work down there,” Caron recounted. “The last time was when I retired 12 years ago. They were looking for a replacement for the job. I asked if I could bid on the job.” He has continued to do the job every spring since.
Caron has an idea when the lamprey come in due to water temperature. He runs the trap a couple of weeks before he gets any in it. He also continues to run it for two weeks after he catches the last one.
When lampreys are captured, Caron is to mark 50 per cent of them with a fin clip up to 25 per day. He puts the fin-clipped lamprey back in Big Creek at Reg. Rd. 45.
“When I catch them again, I weigh them, measure total length and then sex them,” he said. “I cut them open and see if it is a male or female to see what shape their gonads or eggs are in to see if it’s still maturing or mature or ripe (eggs are free flowing).”
He finds 98 per cent are maturing. The lamprey with fin clips that he catches a second time are weighed, measured, sexed and then disposed of, along with any over the count of 25.
They are also passed by a scanner to see if there is a microchip in them. There were microchips put in lamprey in the St. Clair River and they are scanned to see how far the lamprey travel. Any with microchips are frozen after the information is recorded and sent to the lab in Sault Ste. Marie. There, the microchips are removed to see where the chips were originally installed.
Typically, it takes two hours a day to go through the cage and assess the lamprey, but there are times when there are more and it takes four hours. The day Caron was interviewed he caught 38, plus 10 recaptures. Some days he catches 200. There has been up to 400 per day caught. Two years ago, the year after lampricide application in Big Creek – which isn’t done every year- there were only 68 caught all season.
Caron’s job also entails recording all the fish that are captured in the cages and then releasing them on the upstream side of the dam. He sees rainbow trout, catfish, speckled trout, brown trout, perch and even a couple of Atlantic salmon.
For the anglers who are reading this, he predicted the upswing in perch numbers caught this year should be a good sign for the perch fishery in the Inner Bay.