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** Archived Article - please check for current information. **

February 10, 2011

Trammel net surveys over two decades vital to managing fish populations

Recreationally important inshore fish species are now better known after 20 years of study by the S.C. Department of Natural Resources using specially designed trammel nets.

"The trammel net survey is extremely important because it helps fishery managers to better understand fluctuations in inshore fish populations due to factors like drought, unusually cold winters, and harvest," said Wallace Jenkins, fishery manager with the S.C. Department of Natural Resources (DNR). "This survey provides DNR a strong science-based foundation for recommending size and creel regulations to protect and enhance coastal fish populations." Trammel net data are also used in development of regional fishery management plans.

Trammel nets are deployed along the edge of flooded marsh, just as the tide starts to go out. The nets hold but do not injure fish as they attempt to leave the enclosed area with the tide. Biologists then retrieve the fish, record length, weight and species. They also record tag numbers of previously tagged fish and tag fish not yet tagged.

Recapturing these tagged fish over and over again helps determine the size of populations, how far they move, and preferred habitats. With more than 20 years of data collection, trammel net studies have proved vital to developing profiles of inshore fish species and how their populations have changed.

During the past 20 years, more than 17,000 trammel sets have been made, deploying almost 2,000 miles of netting, and catching 353,000 fish of 118 species. The top five catches have been striped mullet (67,168), red drum (64,796), spotted seatrout (53,889), spot (42,600), and southern flounder (18,822).

"We think red drum go through cyclical population changes, based on weather conditions during their fall spawning season," said Dr. Stephen Arnott, coordinator for the study. The trammel data also indicate that southern flounder decline markedly during years of drought, which raises salinity in coastal waters.

Trammel net studies are 50 percent funded through revenue generated by the sale of saltwater fishing licenses, the remainder through federal grants.

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