Aspects of distribution, transport and recruitment of Alaska plaice ( Pleuronectes quadrituberculatus) in the Gulf of Alaska and eastern Bering Sea: comparison of marginal and central populations

Abstract

Shelikof Strait in the Gulf of Alaska appears to be near the extreme warm southern end of the spawning range of Alaska plaice ( Pleuronectes quadrituberculatus). The spawning location, larval transport, and retention in the nursery area are documented from analysis of historical ichthyoplankton surveys of the region. Data from juvenile and adult trawl surveys were analysed to characterise the nursery areas. Aspects of the spawning distribution, population dynamics and juvenile nursery habitat characteristics in the Gulf of Alaska were compared with those in the primary area of its distribution in the eastern Bering Sea. In the Gulf of Alaska, concentrated spawning appears to be localised on the narrow shelf between 50 to 100 m depth on the north flank of the Shelikof Strait Sea Valley and in several other areas. Larvae drift downstream with prevailing currents. Most juveniles are located in water less than 50 m deep over a mud or sand bottom. Over its range, the mean biomass of plaice is related to the amount of suitable juvenile nursery bottom habitat. The abundance of the marginal Gulf of Alaska population is more variable than the main stock of the eastern Bering Sea. Because the continental shelf in the Gulf of Alaska is narrow and suitable habitat is fragmented, it is proposed that the population of Alaska plaice in the Gulf of Alaska is limited by recruitment to suitable nursery habitat, and that there is a dynamic interplay between the landscape ecology and larval drift due to highly variable currents.