Abundance and Sizes of Bay Scallops in Heterogeneous Habitats Along the Gulf Coast of Florida

Southern bay scallops (Argopecten irradians concentricus) form the basis of a recreational fishery along Florida\u27s Gulf Coast. Recent declines in scallop abundances have led to significant harvest restrictions. As a way to gain insight into influences on scallop abundances and size, surveys of bay scallops and coastal habitats were conducted in two relatively undisturbed, shallow estuaries along the north-central Gulf Coast of Florida. Scallop abundances did not vary significantly between years or between locations kilometers apart. Shell heights did vary significantly between years at locations kilometers apart; however, these differences were not consistently related to differences in chlorophyll concentrations in the water column or distributions of benthic habitat classes. At the 100-m scale within locations, scallops were not proportionally distributed across the major habitat classes (i.e., Syringodium filiforme, Thalassia testudinum, mixed seagrass assemblage, other seagrasses, and areas of no/low seagrass cover). In general, proportionately more scallops were observed in association with S. filiforme, T. testudinum, and mixed seagrass habitats. Bay scallops collected from S. filiforme and areas of no/low grass cover were consistently 1-3 mm larger than those collected from T. testudinum and mixed seagrass assemblages. These results suggest the importance of S. filiforme and T. testudinum as habitats for bay scallops. The results also point to the need for further investigation into possible functional differences among seagrass species that may influence the ecology of bay scallops at a small spatial scale and the need for closer examination of scallop movement that may allow for active habitat selection. The work presented here, plus further efforts to elucidate the drivers of small-scale differences in scallop abundances and sizes, will benefit managers who seek to enhance scallop fisheries or protect and restore coastal habitats