Effects of Fishing Practices, Gear Parameters and Gear Configurations on Target and Incidental Catch in the Southern Flounder (Paralichyths lethostigma) Gillnet Fishery of Pamlico Sound, North Carolina

Abstract

In North Carolina, the southern flounder (Paralichyths lethostigma) fishery is one of the most valuable finfish fisheries in the state. A large portion of this fishery occurs during the fall (September 15 to December 15) in the southeastern area of Pamlico Sound, North Carolina, and is conducted with gillnets. The increase in the number of gillnets employed in this fishery has begun to raise concerns among fishery managers and conservationists. These concerns include the reputation that gillnets have for catching large amounts of bycatch, an increase in the number of stranded sea turtles in the area during the southern flounder fall gillnet season, the incidental take of seabirds during gillnet operations and the incidental capture of red drum in southern flounder gillnets.

This study was conducted during the 2000 and 2001 fall southern flounder season to determine the impacts of gillnets on sea turtles, seabirds, red drum, other finfish and invertebrates in Pamlico Sound, North Carolina. The purpose of this study is to examine the catch-per-unit-effort (CPUE) of the target (southern flounder) and bycatch species that is occurring in the southern flounder gillnet fishery of southeastern Pamlico Sound, North Carolina. It is hypothesized that the CPUE of the target and bycatch species will differ between the two areas (deep and shallow), the halves of the fishing season, gear parameters, soak time and gear configurations. The objectives of this study are: 1) To characterize the bycatch composition and distribution that is occurring in the southern flounder gillnet fishery, 2) To test experimental gillnet configurations in an effort to reduce bycatch (emphasis on sea turtle bycatch) without reducing target catch in the deep area of the fishery, and 3) To suggest reasonable and prudent regulations for the fishery.

The sea turtle bycatch was mostly composed of juveniles and subadults Kemp's ridley, green and loggerhead turtles. The majority of the finfish bycatch was composed of Atlantic menhaden and weakfish. Horseshoe crabs composed the majority of the invertebrate bycatch.

Data analyzed from this study has determined that area was a significant factor affecting sea turtle and red drum bycatch. Other factors significantly affecting sea turtle bycatch included length and height of gillnet fished. Mesh size and length were significant factors in red drum and seabird bycatch. Effort was the only significant variable in the finfish analysis. Analysis of the southern flounder CPUE determined that twine size, length, height and soak time are all significant variables. Even though fishing season was not a significant factor in the analysis, the majority of observed sea turtle, seabird and red drum interactions occurred in the first half of the fishing season.

Tie down configuration was an insignificant factor in the sea turtle, seabird and finfish CPUE analysis. However, it was a significant factor in the southern flounder CPUE analysis. Analysis of the experimental gear configurations determined that configuration was a significant variable. The low-profile configuration caught significantly less finfish and invertebrate bycatch than the control and double-lead line configurations. The low-profile configuration also caught significantly less southern flounder than the control.

I suggest that the following regulations be implemented to reduce bycatch of all species in the fall southern flounder gillnet fishery of Pamlico Sound, NC. 1) Move the starting date of the fishery back to October 1. 2) Raise the minimum mesh size to 14.6 cm and lower the maximum mesh size to 16 cm. 3) Implement the use of the low profile configurations for the deep area of the fishery.