First record of the European Giant File Clam, Acesta excavata (Bivalvia: Pectinoidea: Limidae), in the Northwest Atlantic


  • Jean-Marc Gagnon Collections Division, Canadian Museum of Nature, P.O. Box 3443, Station "D", Ottawa K1P 6P4
  • Richard L. Haedrich Department of Biology, Memorial University of Newfoundland, St. John's, Newfoundland A1B 3X7



Acesta excavata, European Giant File Clam, Limidae, Northwest Atlantic, fjord, Newfoundland


Two large bivalve specimens collected in Bay d’Espoir, a deep fjord situated on the south coast of Newfoundland, are described and identified as belonging to the species Acesta excavata (Fabricius 1779). In situ observations onboard the manned submersible PISCES IV and color videos have provided information on the vertical distribution, density and habitat of the species. Maximum abundances of about 15 large individuals/m2 occurred on sheltered rock outcrops at depth ranging from 550 to 775 m, where warm (6°C) continental slope water is found. Differences in shape and thickness between the valves of the two specimens appear to be related to the degree of exposure to rock falls (i.e., sheltered versus exposed habitat). Prior to this account, the European Giant File Clam had never been encountered west of the Azores Islands in the North Atlantic.