By Ray García
Plankton are the preferred food of silver and bighead Asian carp, two of the four main Asian carp species threatening to invade the Great Lakes.
It’s a food source in decline in their current breeding areas. But the fish are still finding lots to eat, making them a greater threat to extend their range, according to a recent study.
These carp eat algae, mussel excrement and many other non-living organic materials, according to the study published in Freshwater Biology earlier this month.
The carp are also capable of fasting for long periods and traveling long distances, said Peter Alsip, a data analyst at the Cooperative Institute for Great Lakes Research in Ann Arbor who led the study. That could be bad news for the Great Lakes.
The fish don’t appear to be overly dependent on plankton and likely wouldn’t suffer if it isn’t around.
“If [Asian carp] chose to go out there, they could mitigate their weight loss and manage their weight loss by feeding flexibly on these different prey items throughout the water column,” Alsip said.
The carp prefer shallow water but can make the journey through deep water to find better areas for food and breeding. These fish have overtaken the Illinois River, which leads to Lake Michigan through the Chicago-area.
“They’re not going to necessarily reside there as these fish will probably want to seek out areas with more food,” Alsip said. “These off-shore areas might just serve as migration corridors for the fish as they seek out these more food-rich waters.”
Preventing the movement of the carp is crucial to keeping them from getting into the Great Lakes, where fishing is a $7 billion industry. They could wreak havoc to the ecosystem, as the carp can take food from native fish and other aquatic life.
The Associated Press reports that the U.S. Army Corps of Engineers this year proposed installing noisemakers, electric barriers and other deterrents near Joliet, Illinois, to keep them away. The new equipment would cost at least $778 million.
“When you consider the possibility that these fish can feed on different prey types and feed at different depth, that really re-enforces the importance of investing in prevention,” Alsip said.
This story was produced by a partnership between WKAR and Michigan State University’s Knight Center for Environmental Journalism.