Restoring bay scallop (Argopecten irradians) in Rhode Island: Progressand pitfalls of the North Cape oil spill program

摘要

In 1996, the North Cape ran aground, releasing 828,000 gallons of oil into Block Island Sound, Rhode Island. Damages included the loss of 150 million surf clams (Spisula solidissima) and 648,000 other bivalves. Settlement was reached in 2000, and state and federal trustees prepared a restoration plan. The plan aims to restore lost shellfish biomass (due to direct loss and foregone production) and ecologic function by releasing shellfish seed. Target species are quahog (Merceneria mercenaria), northern bay scallop (Argopecten irradians), and eastern oyster (Crassostrea virginica). Selection of bay scallop restoration sites was based on habitat and a history of scallops. In September to October 2003, 2.1 million hatchery grown, disease-free scallops with a mean size of 28 mm were released into Ninigret, Green Hill, Potter, and Quonochontaug Ponds. A strong public outreach program helped to gain public support for, and assistance with, the scallop release. During 2004 monitoring surveys were undertaken to determine the abundance and biomass of scallops in the seeded ponds, and comment on the survivorship and growth of the scallop seed. These surveys utilized a stratified random transect design, with divers searching 2 m x 50 m strip transects. Each seeded area was considered an independent stratum, with the unseeded area being stratified by broad habitat type. Post-release surveys conducted in 2003 indicated encouraging scallop survival, although predation by high densities of starfish and crabs were noted at some monitoring sites. The 2004 surveys indicate high mortalities between years. The results are discussed and some options for future restoration are presented.