Stock Assessment and Life History of a Newly Discovered Alaska Surf Clam ( Spisula polynyma) Resource in the Southeastern Bering Sea

• Published in: Canadian Journal of Fisheries and Aquatic Sciences
• Main Authors: Hughes, Steven E., Bourne, Neil
• Format: Article in Journal/Newspaper
• Language: English
• Published: Canadian Science Publishing 1981
• Subjects: Bering Sea; Alaska
• Online Access: http://dx.doi.org/10.1139/f81-158; http://www.nrcresearchpress.com/doi/pdf/10.1139/f81-158

A 1977 exploratory survey of subtidal clam resources in the southeastern Bering Sea revealed extensive concentrations of Alaska surf clams (Spisula polynyma) along the north coast of the Alaska Peninsula. Using east coast hydraulic clam harvesters, subsequent 1977 and 1978 stock assessment surveys delineated a geographically isolated stock with an estimated exploitable biomass of 329 000 ± 52 000 t and conservatively calculated potential annual yield of 25 017 t (maximum sustainable yield) of whole clams. Production fishing trials at 13 sites in 1978 produced an average catch per unit effort of 815 kg/h with a 1.84-m-wide clam harvester.Life history studies indicated the species is long-lived (25 yr), slow growing (K = 0.135), fully recruited to the spawning population at 8 yr of age, subject to low natural mortality (conservatively calculated as M = 0.19), and attains maximum cohort biomass at ages between 9.4 and 13.0 yr. Biological rationale for management measures is presented.Key words: population assessment, sustained yield, surf clams, Alaska