Incidental fishing mortality may be responsible for the death of ten billion juvenile sea scallops in the mid-Atlantic

Abstract

A single large year class in the mid-Atlantic consisting of an estimated 1.31 × 1010 sea scallops was observed in 2003. This year class was 1.1 to 1.6 times larger than the entire scallop stock in any year between 2004 and 2009. Over half of these scallops vanished between 2003 and 2004. This apparent mortality episode was not likely to have been caused by a shift in environmental conditions or by biological factors such as predation, senescence, or food limitation. However, the bulk of fishing effort during that year was focused on the mid-Atlantic. During fishing operations these scallops were brought to the surface through water temperatures above the lethal limit and exposed to high air temperatures before being returned to the sea floor several hours later. Therefore, this mass mortality was likely the result of incidental fishing mortality. The recruitment event was reported to managers on 2 July 2003; however, the area remained open to fishing for another 13 mo before the Elephant Trunk Closed Area was established. Although the Elephant Trunk Closed Area has provided substantial landings for the past 5 yr, the potential of the 2003 recruitment event was only partially realized. Achieving the full benefit of extreme recruitment events requires close ecological monitoring of the target species, real-time abundance and size distribution data, and a management system that can respond rapidly. © Inter-Research 2011.