A variety of eastern Bering Sea (EBS) flatfish including yellowfin sole (Limanda aspera), rock sole (Lepidopsetta bilineata), flathead sole (Hippoglossoides elassodon), and Alaska plaice (Pleuronectes quadrituberculatus), co-occur in various degrees in EBS trawl fisheries, impeding attempts to obtain single-species management targets. A further complication is the bycatch of Pacific halibut (Hippoglossus stenolepis); halibut bycatch limits, rather than single-species catch quotas, have been the primary factor regulating EBS flatfish harvest in recent years. To examine bycatch interactions among the EBS flatfish listed above, an equilibrium mixed-species multifishery model was developed. Equilibrium yield curves, scaled by recent average recruitment, are flat topped or asymptotically increasing, reflecting low fishing selectivity during the first several years of life and low growth relative to natural mortality. A linear programming analysis indicated that relaxation of the halibut bycatch constraint at the optimal solution of catch by fishery would produce approximately 20 times more flatfish yield than a similar relaxation of any flatfish catch quota. A strategy for establishing halibut bycatch limits that considers the foregone revenue in the halibut and flatfish trawl fisheries reveals how the choice of halibut bycatch limit is affected by the management goal for the flatfish complex.
Using ecologically based relationships to predict distribution of flathead sole Hippoglossoides elassodon in the eastern Bering Sea
