Asian carp update

Flying carp coming to a lake or river near you

The term “Asian carp” refers to four species of carp native to the rivers of China and Southeast Asia. All are capable of growing larger than 60 pounds.

Like the common carp, imported from Europe in the 1800s, the fish are in the minnow family.

They’re big minnows.

And like the common carp, Asian carp are quick to establish populations and spread.

The four Asian carp include the grass carp, black carp, silver carp and bighead carp.

The grass carp (aka white amur) was imported for aquatic weed control. The other three — black carp, bighead carp and silver carp — were imported for various aquaculture purposes.

All four Asian carps live in rivers and are thought to require flowing water for successful spawning.

Black carp eat molluscs: snails and freshwater mussels.

Snails are the intermediate host for flukes that infect catfish and hybrid striped bass. Black carp, by ridding the pond of snails, breaks the chain of hosts and eliminates flukes in catfish and hybrid striped bass.

Asian carp of present and greatest concern are bighead carp and the silver carp, collectively called “bigheaded carps” by biologists.

Bighead carp eat zooplankton and, therefore, competes with the adults of a few fish, such as paddlefish and shads, and the young of almost all fishes.

Silver carp are the “flying carp” that exhibits frenzied jumping when boats pass nearby. Of the two bigheaded carps, silver carp appear to be the greater threat in waters in and around Mississippi.

Silver carp eat phytoplankton, which form the base of the food web upon which all fish depend.

Silver carp are abundant in some areas of the Mississippi River and become particularly abundant in floodplain lakes.

Here’s a brief summary of the status of bigheaded carps in Mississippi and neighboring states:

Arkansas: Common to abundant in the Mississippi River, the lower Arkansas River, the lower Black River, the lower St. Francis River and the lower White River.

Louisiana: Abundant throughout the Mississppi River to Head of Passes, the lower Red River and throughout the Atchafalaya Basin. Expansion is expected up the Red River.

Mississippi: Abundant in the Mississippi River, floodplain lakes and the lower Yazoo River, but tributaries have not been thoroughly assessed.

Asian carp have entered the Tennessee River via the Ohio River, and are present in Kentucky Lake.

According to Tyler Stubbs, MDWFP northeast district fisheries biologist, a few adult silver carp have been collected in Pickwick Lake, but the fish have not yet entered the Tenn-Tom Waterway.

It is apparent these fish thrive in our rivers and connected waters, and that they are capable of rapid upstream expansion.

I would expect bigheaded carp to rapidly become abundant if they enter the Tenn-Tom. The shallow, nutrient-rich system closely resembles the Illinois River system where bigheaded carps can exceed 2,000 pounds per acre in shallow river lakes.

While a series of locks and dams separate the 10 lakes in the Tenn-Tom Waterway, locks and dams are not a barrier to these rapidly expanding exotics.

Asian carp are considered a major threat to aquatic ecosystems and human health and safety, and millions of dollars have been spent attempting to contain them. Systems evaluated and in place include electric barriers, seismic water guns, bubble screens, carbon dioxide diffusers, strobe lights and various combinations of these deterrents.

I’ve learned not to underestimate technological development, but at present most of these systems only repel or reduce passage of most Asian carps.

The electric barrier installed to keep Asian carp from moving from the Illinois River into Lake Michigan might be working, but many argue it will not prevent the invasion.

The presence of Asian carp can be monitored by testing the water for their DNA, a surveillance technique called eDNA. Asian carp eDNA has been detected in Lake Michigan in the vicinity of where the Illinois River, via the Chicago River, enters Lake Michigan.

And small fish are less vulnerable to electric fields than large fish, and critics of the barrier question whether it will effectively stop passage of small Asian carps.

Unfortunately, based on their rapid expansion throughout the Mississippi River basin, I can only conclude that invasion of the Tenn-Tom Waterway by Asian carp is not a question of if but when.