Aquaculture for all

Grass Carp Used To Combat Aquatic Weeds

Environment Carp

Biologists with the Louisiana Department of Wildlife and Fisheries recently stocked Spring Bayou with 5,000 triploid grass carp as part of a continued effort to help control unwanted aquatic vegetation.

This is the second installment of grass carp into this complex of shallow sloughs, bayous and lakes. A stocking of 11,000 carp was made in early 2008. Unfortunately, desired results were not achieved due to the effects of Hurricane Gustav that included extensive fish kills.

Aquatic vegetation control in the system was once naturally achieved by water level fluctuations of the Red River, but a dam installed on Little River in 1955 stabilized water levels and curtailed backwater flooding. The absence of water fluctuation, combined with the introduction of the invasive aquatic plant hydrilla, has created the need for extensive control measures. Dredging, water manipulation and herbicides have all been used with limited success. Control by use of grass carp was reserved until all other methods were given ample opportunity.

While use of a biological control measure is an attractive alternative to drawdowns or the long-terms use of expensive herbicides, success using this control method is variable. Potential flood events may allow many of the stocked carp to escape the system. Triploid grass carp are sterile, thus eliminating the concern of the species forming breeding populations in the Spring Bayou or neighboring water systems. However, the risk is that remaining numbers may not be adequate to control the vegetation problem. “At this stage, when boaters aren’t even able to use the complex, we’re willing to try it,” said Mike Wood, LDWF Director of Inland Fisheries.

The stocking was a cooperative effort of the Avoyelles Parish Police Jury, Spring Bayou Restoration Team and Avoyelles Wildlife Federation. The effort received strong support from Senator Eric LaFleur and Repupblican Robert Johnson.

May 2011