The Development of Bycatch Reduction Technology in the Southeastern United States Shrimp Fishery

Abstract

Shrimp trawl bycatch is a significant source of fishery induced mortality for managed species including red snapper (Lutjanus campechanus Poey), Spanish mackerel (Scomberomorus maculatus MitcheU), and weakfish (Cynoscion regalis Baloch, Schneider) in the southeastern United States. These species have been overfished and are under both state and federal management plans which include regulations mandating reduction of shrimp trawl bycatch mortality. In 1990 the U.S. Congress passed amendments to the Magnuson Fishery Conservation and Management Act (16 U.S.C. 1854) which called for a research program that included the design and evaluation of approaches for reducing shrimp trawl bycatch mortality. A strategic planning initiative addressing finfish bycatch in the Gulf of Mexico and southeastern Atlantic shrimp fisheries was developed by the Gulf and South Atlantic Fisheries Foundation through funding and guidance provided by the National Marine Fisheries Service. A cooperative research plan was developed in 1992 which included the identification, development, and evaluation of gear options for reducing bycatch in the Gulf of Mexico and southeastern Atlantic shrimp fisheries. Between 1990 and 1996 one hundred and forty five bycatch reduction conceptual gear designs contributed by fishers, net shops, gear technicians, and biologists were evaluated. Sixteen of these designs were tested on cooperative commercial shrimp vessels by observers under the southeast regional cooperative bycatch program. Analyses of data from commercial vessel testing indicates that two bycatch reduction designs have potential to significantly reduce shrimp trawl bycatch for weakfish and Spanish mackerel in the southeastern Atlantic and two designs have the potential to significantly reduce red snapper bycatch in the Gulf of Mexico. The fisheye and the extended funnel bycatch reduction devices have been mandated for use in the southeastern Atlantic shrimp fishery and the fisheye and Jones/Davis bycatch reduction devices have been mandated for use in the Gulf of Mexico shrimp trawl fishery.

Effectiveness of bycatch reduction devices (BRDs) in the ocean shrimp (Pandalus jordani) trawl fishery

“…Fisheye BRDs (Watson et al, 1999) were allowed in 2001-2002, but were banned in 2003 because they were much less effective than soft-panel and rigid-grate BRDs, which are the only types now allowed (Figs. 1-3).…”

“…Research experiments on bycatch reduction devices (BRDs) have shown many types to be effective at reducing the bycatch of fishes in shrimp and prawn trawls (Isaksen et al, 1992;Broadhurst, 2000;Watson et al, 1999). However, few have been quantitatively evaluated after adoption to determine what level of bycatch reduction was achieved in the fishery.…”

Kemp's Ridley Sea Turtle Saga and Setback: Novel Analyses of Cumulative Hatchlings Released and Time-Lagged Annual Nests in Tamaulipas, Mexico

“…Briefly, according to Watson et al (1986), soft panel separator gear for trawls, designed originally for cold-water shrimp fisheries in the 1960s, were the first turtle excluder gear evaluated for the shrimp fishery. Testing and development in commercial fishing conditions in the Gulf of Mexico indicated a rigid grid was needed due to the diversity in the sizes and types of fish bycatch that clogged or ripped soft panels (Watson and McVea 1977). Oravetz and Grant (1986) describe the adaptation of the "jellyball" shooter, a hooped grid with a slit at the top inserted by Georgia shrimp fishermen ahead of the cod end of the trawl to exclude jellyfish.…”

Size selection of cod by rigid grids—Is anything gained compared to diamond mesh codends only?

“…a narrow selection range (SR; the di erence in length between the 25 and 75% capture probabilities), is preferred. Rigid sorting grids were rst introduced into shrimp trawl sheries to reduce the by-catch of turtles (Watson and McVea, 1977) and juvenile sh (Isaksen et al, 1992). Grids were later modi ed to perform as size selective devices (Larsen and Isaksen, 1993) and a large number of size selective grid designs have been tested in a variety of sheries (Anon, 1998).…”