Validation of Age Estimation in Geoduck Clams using the Bomb Radiocarbon Signal

Abstract

ABSTRACT Geoduck clams (Panopea generosa Gould 1850) are large, deep-burrowing bivalves distributed from southeast Alaska to Baja California. This species supports a lucrative fishery in the states of Washington and Alaska, as well as in British Columbia, Canada, and geoduck aquaculture currently supplies approximately 30% of the market. To manage this species effectively, it is important to elucidate the population age structure. Geoduck ages are currently estimated by counting valve growth rings. We used bomb radiocarbon (14C) to validate geoduck age estimates derived from counts of growth bands in thin-sectioned valve inner hinge plates. Seven specimens with presumed birth years before, during, and after the bomb testing period (1957 to 1967) were sampled from the first 3–5 y of growth, and subsequently assayed for 14C using accelerator mass spectrometry. The 14C values from each of our specimens compared with reference 14C chronologies for the northeast Pacific were in accord at estimated birth years....