The Arkansas Game and Fish Commission and U.S. Fish and Wildlife Service recently tested a new method of fish sampling on the White River that may help monitor the fight against invasive carp.
The electrified dozer trawl method streamlines two previously used sampling techniques to collect information on the populations of silver and bighead carp. These are two invasive species Game and Fish is working to reduce in Arkansas waters.
Previously, biologists would slowly motor through an area and use electricity to stun fish while simultaneously dipping them from the water using long-handled dip nets.
"Dip netting those giant carp can be extremely difficult for the person netting on the front of the boat," said Matt Horton, aquatic nuisance species coordinator for Game and Fish. "You also have some variability between how good different netters are that can make it difficult to get consistent numbers between sampling events."
The "fish dozer" takes that variability out of the equation. Instead of people using dip nets, a device called a push trawl is lowered into the water. The trawl looks like a blade of a bulldozer that's been hollowed out and outfitted with a length of netting as a catch bag that flows underneath the hull of the boat. As fish are stunned by the electric field, the boat cruises over them, securing them in the net.
Jimmy Barnett, invasive carp biologist for Game and Fish, said the dozer testing was conducted in three different scenarios along the White River to determine its effectiveness in varying aquatic habitats. Researchers are testing the experimental gear throughout the Mississippi River Basin to modify the design and technique to optimize carp capture and identify where it is most effective.
Horton said Game and Fish and its partners may be able to more accurately measure the effectiveness of carp removal efforts in some bodies of water using the dozer trawl.