Nottawasaga River & Grand River

The Great Lakes are being threatened by a gluttonous, destructive and fertile foe that threatens to wipe out native fish species, devastate sport and commercial fisheries, and cause far-reaching changes to the Great Lakes ecosystem.

The Asian carp has made its way up the Mississippi River and is poised to invade Lake Michigan.

After escaping from aquaculture ponds in the southern U.S. in the 1970s and ’80s, Asian carp have spread steadily northward. In parts of the Mississippi and other rivers, Asian carp have crowded out native fish and make up as much as 90 per cent of all fish by weight. Only electric barriers in a canal near Chicago are currently keeping the fish out of Lake Michigan.

While there is no indication of the Headwaters region being in imminent danger of a carp infestation, there are many reasons for the Ministry of Natural Resources (MNR) to be both vigilant and proactive.

At present, the common carp is the only species that has established itself in the Great Lakes. Nevertheless, the MNR is aware of how it has upset the balance of the ecosystems it inhabits.

“Common carp aggressively disrupt habitat, uprooting aquatic vegetation and stirring up sediments that impacts other plants and animals,” says MNR Great Lakes research scientist Tim Johnson. “Many coastal wetlands surrounding the Great Lakes and inland lakes suffer from the presence of carp.”

A “carp exclusion system” has been operating at Cootes Paradise, on the extreme west end of Hamilton Harbour, since 1997, and carp control / eradication programs have been used in various inland waters in the U.S. for years in attempts to rebuild healthy ecosystems (abundant plant life) and fisheries.

To draw a comparison, the annual cost of controlling the sea lamprey – another invasive species accidentally introduced to the Great Lakes – is over $15 million.

Feeling the need for a coordinated plan to fight Asian carp led the MNR, with support from the Department of Fisheries and Oceans Canada, to host a “table-top exercise” in March. The exercise simulated an incident where Asian carp get into Ontario waters. The aim was to test if the agencies involved are ready to respond quickly and effectively.

“Preventing Asian carp from spreading into the Great Lakes is the most cost-effective control measure we’ll ever have,” says Ontario Minister of Natural Resources Linda Jeffrey. “This exercise was about making sure all the agencies involved work together, and identifying areas where we’re vulnerable.”

For the March exercise, participants rehearsed how they would respond if an accident on a bridge over the Thames River in southwestern Ontario caused a truckload of live Asian carp to be dumped in and near the river.

A week before the exercise, a fish importer had been fined $50,000 for trying to truck 1,800 kilograms of live Asian carp across the Windsor, Detroit border to sell in the Greater Toronto Area. It’s illegal to possess live Asian carp in Ontario.

The term “Asian carp” includes four species – bighead, silver, grass and black carp. The bighead and silver carp currently pose the biggest threat. They weigh up to 45 kilograms and can grow to more than a metre long. As filter feeders that can eat 20 per cent of their body weight a day in plankton, they’re able to grow and multiply faster than native species. In some areas in the U.S., carp populations are doubling every year.

Silver carp are also a hazard to people on the water. When disturbed by boat motors, the fish jump as much as two metres out of the water.

Of grave concern is how quickly and efficiently this fish can multiply.

The common carp, for example, matures between the ages of two and four. Females can lay anywhere from 100,000 to 2 million eggs that hatch within three to 10 days. Carp grow quickly and can live, on average, of 15 years but may live up to 50 years.

While most studies indicate long reaches of fast flowing water are needed for bighead carp to reproduce, Mr. Johnson points out that silver carp have less dependency on flowing waters and have successfully recruited in reservoirs in China and India.

With such rapid egg development, the risk of eggs succumbing to predation is lower than many native fishes whose development times are much longer.

While it has been calculated that certain carp species can travel up to 60 kilometres a day, it is difficult to ascertain how long it would take for the population to spread.

As robust and mobile as these fish are, the threat of them dominating aquatic ecosystems in Dufferin County is remote.

Should they penetrate the barriers to Lake Michigan and make their way into the other Great Lakes, the carp would spread north, circle around the north end of Michigan and into Lake Huron.

They could then, conceivably, make their way up the Nottawasaga River from Georgian Bay.

While there is no river connection between Lake Michigan and Lake Erie, there is a potential connection via Long Lake, near Akron Ohio, a potential portal that connects the Mississippi River system with Lake Erie.

This would give the carp access to Grand River.

“Scientists are currently investigating questions around rate of spread and possible areas for colonization,” explains Mr. Johnson, “and while there models can make predictions, prevention is by far the most effective management tool to prevent anticipated ecological harm associated with Asian carp.”