U.S. and Canada Scrambling to Prevent Invasive Carp from Reaching the Great Lakes

It seemed like a good idea at the time.

When wastewater treatment plants and catfish farmers in the deep South were looking for ways to remove weeds and eliminate parasites from their ponds in the 1960s and 70s, bringing in bottom feeding carp species from Southeast Asia felt like an environmentally friendly way to do it.

No one knew the carp would turn into an ecological menace a few decades later.

But that’s exactly what happened. Flooding and human activities enabled the carp to escape from confined ponds and sewage lagoons into the Mississippi River basin. From there the fugitive fish quickly spread across large areas of the country via the nation’s maze of rivers.

Workers “electrofishing” Silver Carp at Barkley Dam in Kentucky. Photo courtesy of U.S. Fish and Wildlife Service

The carp now dominate many waterways, lakes and reservoirs in the south, southeast and Midwest, gobbling up algae, plankton, vegetation and shellfish and forcing out native species. Like an aggressive army, they’re constantly on the move and looking to conquer more territory.

Today the United States and Canada spend millions each year trying to prevent the carp from migrating further north and invading the Great Lakes.

“We are on the verge of an unstoppable crisis for the Great Lakes region,” Molly Flanagan, vice president of the Alliance for the Great Lakes, told the Associated Press. “And now is our best chance to stop these aggressive fish from crashing our economy and environment.”

Background

Invasive carp, also known as Asian carp, are actually four different species of fish, all of which have voracious appetites:

• Grass Carp: Present in 45 states, Grass Carp are strict herbivores that can grow up to five feet long and weigh 100 pounds. They can consume a whopping 40 percent of their body weight in aquatic vegetation each day.
• Bighead Carp: Present in 23 states, Bighead Carp primarily consume algae and plankton. Adult bighead can grow up to five feet long and weigh 110 pounds.
• Silver Carp: Present in 17 states, Silver Carp also eat algae and plankton and can grow up to four feet long and weigh 60 pounds. They’re best known, however, for being able to leap 10 feet out of the water when spooked by the sound of a boat engine. There are scores of YouTube videos showing Silver Carp landing in boats, which seems pretty amusing until you contemplate how it would feel to get whacked in the head by one while cruising along at 25 mph.
• Black Carp: Not as widespread as the other species, Black Carp resemble Silver Carp but feast on snails, mussels and other invertebrates. They can grow up to four feet long and weigh 70 pounds. They’re believed to be limited to the lower Mississippi basin thus far.

Needless to say, these fish have left a trail of ecologic and economic damage as they’ve migrated northward. They have evolved into formidable species that are resilient and adaptive. They reproduce earlier in life than native species and lay more eggs. Compounding matters, they have no natural predators.

“They’re such good invaders,” Rebecca Schroeder, aquatic invasive species specialist at Canada’s Invasive Species Centre, told Innovasea Insights.

Woe Canada

Like its southern neighbor, Canada is worried about the rampant spread of invasive carp and what it could mean to its natural resources. Fisheries and Oceans Canada is keeping a close eye on the situation and doing extensive sampling and monitoring in Lake Erie, Lake Ontario and Lake Huron.

Schroeder says grass carp are the primary concern in Canada because they’re already established in Ohio’s Sandusky and Maumee rivers, which feed into Lake Erie. Her organization has been doing public outreach to teach anglers what grass carp look like and asking them report any they catch or see.

“The more eyes on the water the better,” she says.

So far there have been 30 grass carp caught in Canadian waters, but they haven’t yet become an “established” population that’s self-sustaining and reproducing. What if that were to happen?

“It would devastate our wetlands,” says Schroeder, pointing out the ripple effects on native fish, waterfowl, birds, amphibians and overall water quality – as well as the economic damage due to impacts on recreational and commercial fishing, boating and the like.

How to Stop the Carp

Various federal agencies and a number of states are trying to figure out the best way to combat the spread of carp.

“Eradication is the ultimate goal, but suppression and the prevention of carp moving upriver is really what we’re striving for,” said Mark Rogers of the United States Geological Survey.

Innovasea has been at the forefront of the battle against invasive carp for a number of years, with our acoustic telemetry technology being used across the United States to help researchers monitor carp populations, migration patterns and behavior.

Currently the most prominent deployment of Innovasea technology is at Barkley Lock in Kentucky, where the U.S. Fish and Wildlife Service is trying out the nation’s first large scale bio-acoustic fish fence, a three-year project costing $7 million.

The fence produces a curtain of bubbles, light and ear-splitting noise that stretches from the riverbed to the surface. The underwater chaos is intended to prevent the noise-sensitive carp from moving through the lock chamber on Barkley Lake and further on into the Tennessee and Cumberland rivers.

“Today is an important day in the fight against Asian carp,” Margaret Everson of the Fish and Wildlife Service said when the fence was turned on in 2019. “What we learn in Kentucky will directly inform our efforts to protect the Great Lakes.”

Researchers are using Innovasea fish tags, receivers and tracking software to study how the fish react to the BAFF and gauge its effectiveness.

“We are hoping that the BAFF research results indicate that it can successfully divert Asian carp away from dams, lock gates and perhaps out of canals leading to the lock chamber,” said Ron Brooks of Kentucky Fish and Wildlife.

In nearby Kentucky Lake, the USGS used Innovasea receivers and Fathom software to study the effectiveness of herding Silver Carp into a small area using electric and sound stimuli. The results were encouraging and more studies are underway.

Herding the carp into a particular location makes it easier for them to be harvested.

Eat or Be Eaten

Agencies are using other methods to eradicate the carp. Some states are encouraging commercial fishing operations to haul in as much carp as they can, such as Tennessee, where fishermen have removed a whopping 10 million pounds of carp over the last three years.

There are even public education efforts underway to get people to start eating carp using slogans like “If you can’t beat ‘em, eat ‘em.”

That would be an ironic way to rid ourselves of a collection of fish whose insatiable appetite is the source of the problem. But in this fish fight, nothing is off the table.