Population Age Frequencies and Evidence of Multidecadal Recruitment in the Ocean Quahog

Ocean quahogs (Arctica islandica) are the longest-lived, non-colonial animal known today, with maximum life span estimates exceeding 500 years. Ocean quahogs are a commercially important species, inhabiting the continental shelf of the North Atlantic basin. While considerable information exists on the growth and physiology of A. islandica, limited information is available regarding recruitment and how the stock will respond to declines in population biomass due to fishing. A consequence is uncertainty in the biological reference points used to manage the fishery. We examined the age structure of ocean quahogs that were fully recruited to the commercial fishery (>80 mm shell length) from 4 sites covering the range of the stock within the US exclusive economic zone (EEZ) off the northeast coast of North America. Terminal goals of this study are (1) to use population age frequencies from each of the 4 sites to develop an age-length key enabling reconstruction of population age frequency, (2) to identify the periodicity of recruitment in this long-lived bivalve and (3) to develop a long-term recruitment index that will reduce uncertainty in the status of the stock and fishery by establishing a basis for improved biological reference points.