Climate-Induced Changes in the Performance of the Mid-Atlantic Surfclam Fishery: Is Bigger Better?

Despite increasing evidence of climate-induced range shifts in marine populations, fisheries management remains based on catch projections that discount environmentally driven changes in the target species distribution. The Mid-Atlantic Bight (MAB) surfclam (Spisula solidissimus) fishery is among the most valuable shellfisheries in the U.S. and warming of the MAB has triggered a northward shift of the surfclams. To examine the effects of a northward shift in surfclam distribution on the fishery, we used an individual-based model that integrates population dynamics, vessel/industry economics and captain behavior. We performed 50-year simulations for 24 scenarios: three surfclam ranges, four boat types and two distinct captain behaviors (exploratory and conservative). As expected, vessel effort shifted northward and unused quota for the southernmost processing plant increased regardless of boat type. Interestingly, unused quota of the other four plants varied with boat type. Only the largest vessel used its entire quota for these four plants in all three surfclam ranges suggesting that the large vessels can better cope with changes in surfclam range. Our findings demonstrate the need to account for climate-driven changes in managing marine species, in particular shellfish species such as surfclams whose relatively specialized ecological niche make them prone to range shifts.