Performance of low-profile skimmer trawls in the inshore shrimp fishery of North Carolina

摘要

A gear development study was conducted during May-June 1995 comparing the catch composition of shrimp (family Penaeidae) and finfish bycatch in a standard high-profile skimmer trawl (3.7-m vertical height) and a low-profile skimmer trawl (0.9-m vertical height) in the North and Newport rivers, North Carolina. As opposed to the traditional otter trawl, a skimmer trawl is a net attached to frames and pushed rather than pulled by the vessel. The low-profile net was designed by commercial fishers in the hope of reducing finfish bycatch and the capture of floating debris. The objective of the study was to determine whether a reduced vertical height actually reduced finfish bycatch, while minimizing losses of brown shrimp Penaeus aztecus and pink shrimp P. duorarum. White shrimp P. setiferus were not present during the study period. Total shrimp catches (including discard shrimp) with the low-profle net were significantly smaller than with the high-profile net. Brown shrimp catches were smaller by 39.1%; pink shrimp catches were not significantly different, probably because of low abundance during the study period. Subsamples indicated that the proportion of finfish biomass in the total catch to shrimp biomass was similar between the two nets: 2.08:1 (67.5%) for the low-profile net and 1.63:1 (62.0%) for the high-profle net. Of the six commercially important finfish species caught, only spot Leiostomus xanthurus and Atlantic croaker Micropogonias undulatus had different length frequency distributions in the two nets. Brown shrimp catches were significantly smaller in the low-profile net, regardless of light conditions, tide stage, or lunar phase. The low-profile net did not reduce bycatch under most conditions: however, it does permit shrimping under moderate wind conditions, in areas where tight turns are mandated, when large amounts of floating debris are present, and in shallow water.