Distribution and abundance of the Pacific razor clam, Siliqua patula (Dixon) on the eastside Cook Inlet beaches, Alaska

Abstract

Three questions were asked about the population of the Pacific razor clam Siliqua patula (Dixon) on eastside Cook Inlet beaches: (1) can density be estimated by a three-stage stratified random sampling plan; (2) can age composition data be used for age-structured population estimation; (3) does substrate composition affect clam density? Field studies of Coho, Ninilchik and Clam Gulch beaches obtained precise density estimates for Clam Gulch beach only (coefficient of variation = 14.6%, 1988, and cv = 13.6%, 1989). A heavily exploited area of high density at Clam Gulch was resampled extensively in 1989 to determine if a significant harvest rate was detectable. No significant harvest rate was detected. A catch-at-age model was successfully applied to age-structured data, and estimates of abundance for ages 4 through 11+ in years 1977 to 1989 were generated. There is some evidence from substrate analyses that clams are found in higher abundance where grain sizes 0.125 to 0.400 mm predominate.