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Comparisons between a skimmer trawl and an otter trawl in the North Carolina shrimp fishery / by J. Stuart Coale.

Author/creator Coale, J. Stuart author.
Other author/creatorRulifson, Roger A. (Roger Allen), 1951- degree supervisor.
Other author/creatorEast Carolina University. Department of Biology.
Format Theses and dissertations and Archival & Manuscript Material
Production Info 1993.
Descriptionv, 58 leaves : illustrations, map ; 28 cm
Supplemental Content Access via ScholarShip
Subject(s)
Summary The skimmer trawl, used in Louisiana exclusively for shrimping, is pushed in pairs alongside the vessel, whereas the otter trawl is towed behind the vessel. Shrimp fishermen in North Carolina use the otter trawl, a highly unselective type of gear, which catches an incidental and unwanted (unmarketable) mix of species known as bycatch. The purpose of this study was to compare the skimmer trawl and otter trawl fisheries and the different methods used in each, as well as to determine if the skimmer trawl tends to reduce bycatch and improve bycatch survivability in North Carolina waters. Gear comparisons were conducted at night in inshore protected waters using a skimmer trawl vessel and a comparably-sized otter trawl vessel fishing in close proximity. For each gear type, bycatch was quantified by species, and live well experiments were used to determine bycatch survivability. On average throughout the study, the skimmer trawl caught less bycatch (mean = 0.47 kg/min) than the otter trawl (mean = 0.66 kg/min), and had the lowest bycatch rate (mean = 0.30 kg/min) and fish-to-shrimp ratio (mean = 1.38) during the peak of the white shrimp season. The skimmer trawl proved very effective for catching white shrimp (Penaeus setiferus): this species comprised 23.3% of the total skimmer trawl biomass compared to 5.1% of the total otter trawl biomass. On the other hand, brown shrimp (Penaeus aztecas) comprised only 6.1% of the skimmer trawl biomass compared to 16.8% of the otter trawl biomass. Of the 20 different species tested in live wells, 15 species showed decreased mortality when caught by skimmer trawls. Significant differences in length frequencies between the two gears were observed for five finfish species. Use of the skimmer trawl in the North Carolina shrimp fishery may increase white shrimp catch while reducing bycatch and mortality rates of most species.
General noteSubmitted to the faculty of the Department of Biology.
General noteAdvisor: Roger A. Rulifson
Dissertation noteM.S. East Carolina University 1993
Bibliography noteIncludes bibliographical references (leaves 51-53).
Genre/formdissertations.
Genre/formAcademic theses
Genre/formAcademic theses.
Genre/formThèses et écrits académiques.

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