DV-15-16 Comparative Genetics of Soft-Shell Clams in Penobscot Bay & the Gulf of Maine

Jennifer Couture Phillips
University of Maine School of Marine Sciences

The soft-shell clam fishery on the coast of Maine has significant economic and cultural value to the state. In recent years, community fishery managers in areas where clam populations have declined have taken to seeding hatchery-raised juvenile clams onto mud flats to bolster populations. One threat to the survival of the seeded clams is the occurrence of harmful algal blooms of the species Alexandrium, which are especially damaging to juvenile clams.

Field and lab experiments have identified a genetic mutation in some soft-shell clams that allows them to thrive in the presence of Alexandrium; however, when Alexandrium is not present, these same clams don’t do as well as clams lacking the mutation. Knowing which populations are likely to thrive in a given area will help managers make decisions about clam flat seeding and restoration. This project will analyze the DNA of clams in Penobscot Bay, where Alexandrium blooms are rare due to constant flow of surface water out of the bay. In this absence of Alexandrium blooms, it is hypothesized that the Bay will have fewer clams with the resistant mutation, and that the clams would be genetically isolated from other Gulf of Maine populations due to a lack of larval transport into the bay. The results will help shellfish managers make decisions about sourcing clam seed. This project is part of a larger study of the genetic make-up and gene flow structure of Gulf of Maine clam populations.

Sea Grant funds: $4,000