Eelgrass (Zostera marina) Response to Bay Scallop (Argopecten irradians irradians) Dragging in New England USA

Northern bay scallop (Argopecten irradians irradians) fisheries occur seasonally in late autumn and winter in southern New England USA. Fishing effort often overlaps spatially with eelgrass (Zostera marina), an important bay scallop habitat. While bay scalloping has persisted in coastal waters of southern New England since the late 1800s, surprisingly little data exist to assess potential habitat impacts of this fishery. To address this data gap, we completed a field study in southeastern Massachusetts USA consisting of (1) low and high intensity scallop dragging at experimental eelgrass beds in Nasketucket Bay and the Westport River and (2) a control-impact assessment of a commercially and recreationally dragged bed in the Westport River. We used drop camera imagery to estimate eelgrass percent cover and side-scan sonar to assess bed extent during different seasons for three consecutive years. Eelgrass percent cover and bed extent declined at the bed exposed to high commercial and recreational dragging, but declines appeared to be related to smothering from local diatom blooms rather than physical disturbance. Eelgrass plots subjected to high intensity experimental dragging had lower winter and summer eelgrass percent cover for one of the three sampling years relative to low intensity dragged and control plots in Nasketucket Bay while no changes in eelgrass percent cover related to dragging treatments were detected in the Westport River. Results generally showed a lack of long-term impacts to eelgrass beds in response to bay scallop dragging, but other ecological effects associated with commercial and recreational fisheries warrant further consideration.