Age and Growth of the Giant Pacific Sea Scallop, Patinopecten caurinus, from the Strait of Georgia and Outer Washington Coast

Abstract

At any given age, giant Pacific sea scallops, Patinopecten caurinus, from an inner coastal area of Washington (Strait of Georgia) were about 1.5 times as large as those from an outer coastal area (near Destruction Island). Annuli were apparently formed during the winter. Lee's phenomenon, i.e., a slower estimated growth for young animals when calculated from successively older individuals than the true average growth, occurred m the outer coast data but not in the Strait of Georgia data. Differences in size between populations at the same ages apparently resulted from differences in the amount of growth during early years of life, because growth rates in later years differed little. Differences in growth rate were more likely to be due to hydrographic conditions than to infestations by boring annelids. Growth rate of the scallops in the Strait of Georgia was similar to that reported for the species off Kodiak Island, Alaska, to about 135 mm; thereafter, Strait of Georgia scallops grew more slowly.