Red king crab ( Paralithodes camtschaticus ) formerly represented one of the most lucrative fisheries in the Bering Sea and Gulf of Alaska. Following rapid capitalization, the fishery exploded in the late 1970s with peak catches nearing 70,000 tons in the eastern Bering Sea alone, but in the early 1980s the productivity of this fishery collapsed by over an order of magnitude. Despite extensive management effort, harvest levels have remained fairly low and stable for the last 15 years. Factors in the life history of Alaskan red king crab and the Bering Sea ecosystem are discussed, especially as they pertain to continued low crab biomass. Reduction in crab abundance due to natural predators, habitat and resource limitations, and human impacts may present "bottlenecks" to future recruitment at a number of different life history stages. These stages include egg and larval supply, the early benthic phase, pre-fishery juveniles, and breeding adults. There is evidence that an environmental "regime shift" may have occurred in the late 1970s characterized by warming sea surface temperatures, altered circulation patterns, and changes in the productivity patterns of the Bering Sea and Gulf of Alaska. Since this period, a number of potential predators and resource competitors of the red king crab have increased in abundance, including pelagic planktivores and a number of invertebrate and benthic fish species. The suite of changes in the ecosystem since the 1970s may have altered the relative importance of survival at different ages as the ultimate regulator of population abundance and fishery recruitment in red king crab. We suggest that the successful management of this species, and sensitive species in general, relies on attention to the species' particular life history patterns and population bottlenecks. Specifically, management must focus on identifying and reducing anthropogenic impacts on valuable species. These impacts may be direct, such as capture in fisheries, or may be indirect, impacting the target species via effects on other species with which it interacts. We use this ecosystem management approach (the "Critical Intersections Approach") as a model to suggest a shift in red king crab management. Present scenarios for red king crab concentrate on maximizing female biomass, but this approach may not be sufficient to increase population levels. Evidence exists that total egg supply may not be the primary limiting factor presently controlling crab abundance in the Bering Sea. Rather, survival during early post-settlement stages may regulate overall recruitment to the fishery. Given this possibility, we present a hypothetical biological and economic management plan that encompasses, (1) near-shore trawl management areas to protect crab nursery habitat, (2) deeper-water trawl management areas to protect breeding stock, (3) encouragement and incentives to fisheries that reduce crab-predator biomass, (4) establishment of ITQs for the fishery, (5) introduction of mandatory increased utilization of harvested crab, and (6) integrating a research program into the management plan.
low crab biomass
Document Type: Research Article
University of Washington, School of Fisheries, Box 357980, Seattle, WA 98109
National Marine Fisheries Service, National Marine Mammal Laboratory, 7600 Sand Point Way NE, Seattle, WA 98115
National Marine Fisheries Service, Sustainable Fisheries Division, P.O. Box 2166B, Juneau, AK 99802
Channel Islands National Marine Sanctuary, 113 Harbor Way, Santa Barbara, CA 93109
September 1, 1998