Identifying the Historical Footprint of the Surfclam Spisula Solidissima and Habitat Relationships from a Long-Term Dataset of Death Assemblages and Sedimentology

The Atlantic surfclam, Spisula solidissima, is a commercially important bivalve in the Mid-Atlantic Bight. As a result of rising bottom water temperatures, the range of this species has contracted offshore and towards the northeast. The National Marine Fisheries Service has conducted surveys since 1978 to assess the abundance and location of the stock. Information regarding by-catch including shells of a suite of species, such as the long-lived Arctica islandica, was also logged. The distributions of shells mark the historical footprint of these species: comparison to their present distribution maps the degree to which their range has shifted over time. The by-catch data also permit mapping where substrate complexity exists as indicated by cobbles, rocks and boulders. Such areas may provide habitat for sessile attached species such as corals, mussels, and sponges. Avoidance of areas where large rocks and boulders exist is also desirable for the commercial fishery to reduce damage to fishing gear. The objectives of this project are to track the shift in range of the surfclam stock using the death assemblage to establish the historical footprint of this and other species and to identify areas of increased substrate complexity offering potential habitat for sessile attached organisms.