Fishing Practices Under Maximum Retainable Bycatch Rates in Alaska's Groundfish Fisheries

Most groundfish species managed by the North Pacific Fishery Management Council are closed to directed fishing for a portion of the fishing year for various reasons, the most common being the attainment of the total allowable catch (TAC) or the seasonal allowance of the TAC. Bycatch of non-targeted groundfish species for which directed fishing is closed may be retained in other fisheries up to a maximum retainable bycatch (MRB) level established by regulation as a percentage of the directed catch retained during a fishing trip. For some species, MRB percentages are generously set at levels that exceed “natural” bycatch rates to maximize the opportunity to retain these non-targeted species while reducing overall harvest rates. When the bycatch species is more economically valuable than the target species an incentive exists to “top off ” by targeting the bycatch species until the MRB level is attained. We contrast 2 fisheries in which topping-off behavior was previously anecdotally reported. Because of differing species spatial distributions, some rockfish fisheries, Sebastes and Sebastolobus, in the Gulf of Alaska usually have an observed sablefish Anoplopoma fimbria bycatch rate below the prescribed MRB. These natural bycatch rates were estimated based on National Marine Fisheries Service survey and observer program fishery data. The estimated bycatch rates were reasonably precise with most coefficients of variation less than 50% for species of interest. By examining the observed catch from individual trawl hauls in a geographical information system, we were able to demonstrate topping-off behavior with more valuable sablefish in the rockfish fishery. The temporal and spatial targeting patterns of individual vessels were tracked, and distinctive hauls with sablefish as the dominant catch were identified. Similarly, shortraker Sebastes borealis and rougheye S. aleutianus rockfish are more valuable than Pacific ocean perch S. alutus in the Aleutian Islands, and there were anecdotal reports of topping-off with the shortraker–rougheye management complex of rockfish. However, our analysis did not reveal strong evidence of this practice. Authors: DAVID R. ACKLEY is a fisheries management specialist with the National Marine Fisheries Service, Sustainable Fisheries/Alaska Region, P.O. Box 21668, Juneau, AK 99802. David R. Ackley’s email: david.ackley@noaa.gov. JONATHAN HEIFETZ is a fishery research biologist with the National Marine Fisheries Service, Auke Bay Laboratory, 11305 Glacier Highway, Juneau, AK 99801. Acknowledgments: Sue Salveson of NMFS, Alaska Region — edits and contributions to original drafts of this paper. Gordon Kruse of the Alaska Department of Fish and Game — his insight and suggestions. The National Marine Fisheries Service Observer Program — data contributions. Funding from the Alaska Fisheries Information Network (AKFIN) also made this paper possible.