Large-Scale Closed Areas as a Fishery-management Tool in Temperate Marine Systems: the Georges Bank Experience

• Main Authors: Murawski, S. A., Brown, R., Lai, H.-L., Rago, P. J., Hendrickson, L.
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: Digital Commons @ University of South Florida 2000
• Subjects: Life Sciences; atlantic cod; Gadus morhua
• Online Access: https://digitalcommons.usf.edu/msc_facpub/2129; https://www.ingentaconnect.com/content/umrsmas/bullmar/2000/00000066/00000003/art00020

Seasonal closed areas have been an element of fishery management in New England waters since 1970 but before 1994 had limited impact on the conservation of groundfish stocks for which they were designed. Beginning in December of 1994, three large areas of historic importance to groundfish spawning and juvenile production on Georges Bank and in Southern New England, totaling 17,000 km2, were closed year-round to any gears capable of retaining groundfish (trawls, scallop dredges, gill nets, hook fishing). In the ensuing five years, the closed areas contributed significantly to reduced fishing mortality of depleted groundfish stocks. Placements of the closed areas afforded the greatest year-round protection to the shallow-sedentary assemblage of fishes (primarily flounders, skates, and miscellaneous others) and bivalve molluscs. Although the closures afforded less year-round protection to migratory age groups of Atlantic cod, Gadus morhua, and haddock, Melanogrammus aeglefinus, additional new regulations in open areas and in the Canadian portions of Georges Bank also contributed to the observed reductions in stock-wide fishing mortality rates. The areas were closed to dredge gear designed for sea scallops, Placopecten magellanicus, because of groundfish by-catch (particularly of flounders). Scallop biomass increased 14-fold within the closed areas during 1994–1998. In July 1998, total and harvestable scallop biomasses were 9 and 14 times denser, respectively, in closed than in adjacent open areas. A portion of the closed areas was designated a "habitat area of particular concern" on the basis of patterns of occurrence of juvenile groundfish in gravel/cobble sediment types. Managers reopened portions of one closed area to sea-scallop dredging in 1999, but restrictions on gear and areas fished were used to minimize groundfish by-catch and impact on juvenile cod and haddock on gravel substrates. Results from these reopenings have encouraged managers to contemplate a formal 'area rotation' scheme for scallops intended to improve yield per recruit. Closures of large portions of Georges Bank have proved to be an important element leading to more effective conservation of numerous resource and nonresource species, despite selection of the closed areas on the basis of seasonal spawning grounds of haddock and the distribution of yellowtail flounder, Limanda ferrugineus, in southern New England. In the future, factors other than fishing mortality reduction, including optimal placement to enhance larval production and to protect nursery areas and spawning concentrations, may well influence the selection of closed-area boundaries.