The speckled scallop, Argopecten circularis, in Aqua Hedionda Lagoon, San Diego County, California

Abstract

Speckled scallops, Argopecten circularis (Sowerby, 1835), were sampled at Agua Hedionda Lagoon, Carlsbad, San Diego County from March 1984 to October 1986, to obtain basic life history data. Monthly samples of scallops were collected, measured, and released to obtain length frequency data for estimates of growth, life span, and spawning period. Subsamples of scallops were collected for determination of gonadal-somatic and adductor muscle-somatic indices.In 1984 large concentrations of speckled scallops were found on the sand-silt bottom of the lagoon, closely associated with eelgrass, Zostra marina. During the course of the study the numbers of scallops declined, until their virtual disappearance at the end of 1986. Monthly length frequency plots from 24,375 scallop measurements indicate that this is a rapidly growing species with a short life span. Gonadal- and adductor muscle-somatic indices from subsamples of 1,714 scallops indicate first spawning at age one and a relationship between temperature and spawning.Based on this study management recommendations are made for the speckled scallop. (39pp.)