Evaluation of a Spatially-Explicit Fisheries Economics Simulator (SEFES) for the Mid-Atlantic Surfclam Fishery

The influence of climate-induced range compression on the surfclam stock of the Mid-Atlantic Bight (MAB) has engendered significant changes in fleet dispersion amongst ports and in the economics of the industry. A spatially-explicit fisheries economics model (SEFES) has been developed to evaluate how changes in stock distribution force responses in the fishery. Fishing location is determined by port location, vessel characteristics, Captain’s behavior, and stock density. The model reproduces and explains known characteristics of the fishery, including the limitation of the fishery predominately to a few 10-minute squares and the half-decadal to decadal decline of LPUE within heavily-fished 10-minute squares. The model suggests that Captains’ limited knowledge of the stock beyond their known recent fishing areas permits 10-minute squares to recover for a period between the time when a drop in LPUE forces their abandonment and the time when the fishery “re-discovers” the resource. Some 10-minute squares remain productive for the fishery over decadal time periods, even with continuous targeted harvesting, while productivity in others rapidly declines, as also is observed in today’s fishery.  Vessel speed, hold capacity, and dredge size are important determinants of the degree of dispersion of fishing among 10-minute squares.