Invasive asian carp are threatening to take over Lake Erie, according to reports of sighting on both the Canadian and U.S. sides of the lake, with concerns now rising about the invasive species making it through the entire Great Lakes chain.
First introduced to North America in the 1960s and 70s by commercial fish farmers as a way to clean out ponds of plant matter, the fish with the voracious appetite -there are four species included under the heading of Asian carp: the silver, bighead, grass and black carp- has spread unrelentingly across the continent, depleting rivers and lakes of food resources and crowding out other species.
Officials say that Asian carp make up 50 per cent of the fish by weight in some parts of the Illinois River and have all but replaced native species in parts of the Mississippi River and its tributaries. In Canada, an Asian grass carp was caught earlier this year by Quebec fishers along the St. Lawrence River, with another grass carp being found in Lake Erie near Point Pelee, as well.
“We know with Asian carp we don’t want them here,” said Jolanta Kowalski, spokesperson for the Ministry of Natural Resources and Forestry, in response to the Lake Erie finding.
“They are a problem fish and will outcompete others for food. Anything we can do to avoid a population base is the route to go. They are an invasive species.” Kowalski said that the grass carp found near Point Pelee was 94.5 cm in length and weighed 10.1 kg. The carp have been known to grow to as large as 40 kg and over a metre in length.
Canadian and U.S. officials are taking steps to combat the spread of the fish, but research currently under way at the Sandusky River of north-central Ohio is being questioned for its possible contribution to the problem. According to the Detroit Free Press, the multi-year project aims to to study the breeding habits of the fish by fixing some with transponders to track them as they make their way to their breeding grounds.
And while a common practice when tracking invasive species is to sterilize them before releasing them into the wild, this practice has not been followed for the Asian carp study, authorized by the Michigan Department of Natural Resources (DNR), with the claim being that putting fertile carp back into the ecosystem is necessary to locate spawning grounds. “We have to find where the fish spawn. We can’t do that with [sterile fish],” says Tammy Newcomb, senior policy advisor for Michigan’s DNR.
Not good enough, says Nick Mandrak, with the University of Toronto, Scarborough, and expert on aquatic invasive species. Mandrak says that research has already accurately predicted spawning grounds along Ohio’s Sandusky River. “Published models in 2012 predicted within a few kilometers where in the Sandusky River they might be spawning,” says Mandrak. “Recently, some fertilized eggs were found there. Now some of the ones they’re tagging are also going up that river. We have the information, so what are we going to do? How many fertile fish do we need to let go before we decide to take action to prevent spawning — right now?”
The U.S. Geological Survey has stated that if Asian carp start breeding in Lake Erie, they will have more than enough food from the lake’s huge algal blooms to thrive.