Conserving oyster reef habitat by switching from dredging and tonging to diver-harvesting

Commercial fishing for demersal fishes and benthic invertebrates, such as mollusks and crabs, is commonly undertaken with bottom-disturbing gear that can inflict damage to seafloor habitats (Dayton et al., 1995; Engel and Kvitek, 1995; Jennings and Kaiser, 1998; Watling and Norse, 1998). Habitat damage from dredges and analogous gear, designed to excavate invertebrates that are partially or completely buried beneath the surface of the seafloor, is generally much more severe than the damage caused by bottom trawls (Collie et al., 2000). Furthermore, impacts on and recovery from bottom-disturbing fishing gear vary with habitat type; generally smaller effects and more rapid rates of recovery are found for infauna in sedimentary habitats and the most severe and long-lasting damage in biogenic habitats that emerge from the seafloor (Peterson et al., 1987; Collie et al., 2000). Such biogenic habitats include seagrass beds, fields of sponges and bryozoans, and invertebrate reefs. Biogenic reefs that provide important ecosystem services such as habitat for other organisms include not only tropical coral reefs but also temperate reefs constructed by oysters (Bahr and Lanier, 1981; Lenihan et al., 2001), polychaetes like Petaloproctus (Wilson, 1979; Reise, 1982), and vermetid gastropods (Safriel, 1975). The recovery of such emergent invertebrate reefs is a slow process because of the relative longevity of the Conserving oyster reef habitat by switching from dredging and tonging to diver-harvesting