Effects of commercial fishing on local abundance of Pacific cod (Gadus macrocephalus) in the Bering Sea

• Main Authors: Conners, M. Elizabeth, Munro, Peter
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2008
• Subjects: Biology; Ecology; Fisheries; Bering Sea; Pacific
• Online Access: http://hdl.handle.net/1834/25481

Groundfish fisheries in the southeast Bering Sea in Alaskahave been constrained in recent years by management measures to protect the endangered Steller sea lion (Eumetopias jubatus). There is concern that the present commercial harvest may produce a localized depletionof groundfish that would affect the foraging success of Steller sea lions or other predators. A three-year field experiment was conducted to determine whether an intensivetrawl fishery in the southeast Bering Sea created a localized depletion in the abundance of Pacific cod (Gadusmacrocephalus). This experiment produced strongly negative results; no difference was found in the rate of seasonal change in Pacific cod abundance between stations within aregulatory no-trawl zone and stations in an immediately adjacent trawled area. Corollary studies showed thatPacific cod in the study area were highly mobile and indicated that the geographic scale of Pacific cod movementwas larger than the spatial scale used as the basis for current no-trawl zones. The idea of localized depletionis strongly dependent on assumed spatial and temporal scales and contains an implicit assumption that there isa closed local population. The scale of movement of target organisms is critical in determining regional effects offishery removals.