by Kory Riemensperger
There’s a silent invader in Tennessee rivers, lakes and streams. Some people fear it, some are making light of it, and some are simply trying to understand it.
In the ‘70s, Arkansas fish farmers introduced two species of Asian carp, silver and bighead, to curb algae growth. In floods, the fish escaped into nearby rivers. Since then, they have swum into many American river systems. Tech fisheries professor and U.S. Geological Survey Scientist Phillip Bettoli says anecdotal evidence suggests the carp are now reproducing in Tennessee.
The silver carp is known for its tendency to jump out of the water when frightened. A single jump can start a chain reaction of frightened fish. In YouTube videos, waterskiers try to net the jumpers or even slice them with a sword.
Bettoli said that his students have brought motorcycle helmets to go fishing before: these carp can weigh up to 60 pounds; collisions with people or property can cause serious damage.
At Tech, graduate research assistant Josey Ridgway and Bettoli are developing a scientific way to understand the environmental impact of these large, invasive fish. With nets and electrofishing tools, they measure the weight, height, sex and age distribution of carp in Tennessee and Kentucky.
The age of a silver carp can be determined by examining its otolith, a bone found in the inner ear of most fish. Like the rings of a tree, examining the bone reveals a fish’s age and helps researchers study a species’ movement patterns.
“They’re not that bad in Tennessee yet,” said Bettoli. “And that’s what the fear is, particularly where we’re seeing adults reproducing, something we haven’t seen before. It could be exciting times ahead for everybody.”