Stopping the invasion
Fisheries and Oceans taking aim at the Asian carp
Two hours. That’s the time it takes Fisheries and Oceans Canada aquatic science biologists to determine if an invasive Asian carp is fertile or sterile.
And those results dictate the level of response from the federal agency, said Becky Cudmore, manager of its Asian carp program.
“It changes our level of emergency. If a fertile fish is found, our emergency level goes up and we put boats on the water,” said Cudmore from the shore of the Grand River last week in Dunnville during an Asian carp exercise.
The on-water exercise, which involved federal and provincial agencies, was a demonstration of techniques used to search for and capture Asian carp.
“This is the first on-water exercise we know of in Canada for invasive species. What we are specifically looking for and dealing with are Asian carp, which are priority for the government of Canada and province of Ontario. We are practising for an emergency situation so we are well prepared should we detect any in Canadian waters,” said Cudmore.
She said the federal agency has been tested in the past, and has implemented an emergency response to the invasive species of carp, of which there are four types — grass, bighead, silver and black.
The exercise, observed by Grand River Conservation Authority, was an opportunity to be ready for the field season, Cudmore said.
With three grass carp caught in the Dunnville area over the past number of years, she said that species is the one being targeted by Fisheries and Oceans. One grass carp caught in the area in 2013 was 104 centimetres long and weighed 14 kilograms. Testing at the time confirmed the carp was sterile.
“The grass carp do a great job, almost too good of a job, at eating aquatic plants that form part of the wetland habitat.”
Native fish depend on those habitats and if they were to disappear, there would be a decline in native fish populations, Cudmore said.
“A lot of those species we rely on for recreational and commercial uses. And those wetlands are really valuable for waterfowl. The loss of wetlands would be devastating for the Great Lakes ecosystem.”
Cudmore said the grass carp are at a stage in the invasion process that “we weren’t aware of.”
“We knew that they had been arriving and showing up here and there,” she said, adding a fertile grass carp was found in the Canadian waters of Lake Ontario in 2015.
“Invasions go through stages. First the fish show up here and there, then they show up more frequently and that becomes arrival, and then they start to reproduce and establish the next generation and start to spread and have an impact.”
She said grass carp are at the arrival stage now, and the federal agency must work to ensure the fish don’t reproduce and establish themselves in the ecosystem.
Part of the exercise, she said, was about the various agencies working together to co-ordinate efforts to stop the invasion.
“We have to be more in emergency mode now and respond and remove them.”
The capture of the grass car pin Lake Ontario was a surprise, Cud more said, as the agency had made Lake Erie its priority. It now works on both lakes.
“We’ve captured more over time, but we’re out looking more. It’s hard to say if there are more out there or we’re just better at catching them now.”
Cudmore said with a shoreline full of areas with vegetation and woody areas, from fallen trees, the Grand River is one body of water that needs to be watched. She said grass carp like really big rivers and like to hide in the vegetation and woody areas.
Other factors that influence where the invasive carp species may include the depth and flow of a body of water, the number of sunny days and water temperature. All of those factors are plugged into a computer model that can give an idea of where the fish may be found, and Fisheries and Oceans staff can go and check those areas to see if the model is correct.
The agency is now up to 36 early detection sites that it visits at least once a year to check for the invasive fish, and there are other sites it visits more frequently, as many as three to four times a year.
Cudmore said some people argue nothing should be done with the invasive species, that they should be allowed to establish themselves and they’ll eventually level out, much like the common carp did.
“The common carp species has been here 200 years and the population has levelled out,” she said, adding that species caused damage over time when introduced to the Great Lakes system.
“Are we willing to live with the consequences of what would occur over the next 200 years? We’re not, we’re going to ensure the carp don’t get a hold in the system.” dajohnson@postmedia.com Twitter: @DaveJTheTrib