Spatially-Explicit Fisheries Economics Simulator: A Predictive Tool of Climate-Induced Effects on Harvesting Performance

Climate regime shifts can exert bottom-up effects (through changes in stock distribution and abundance) on a fishery system followed by top-down effects (through shifts in fishing fleets and processing industry). A holistic, dynamic approach to stock assessment that can help forecast the interplay of bottom-up and top-down effects driven by climate, is needed.

The valuable Mid-Atlantic Bight surfclam (Spisula solidissimus) fishery experienced a drastic northward shift and contraction of the stock range. To understand the implications of this stock shift on the fishery, we used an individual-based model (SEFES) that integrates clam dynamics, harvesting quota system, vessel and industry catch and economics. We performed 50-year simulations on past (baseline) and future (compacted) stock ranges. We compared performance (landings per unit effort, revenue, unused quota) of different vessels associated with processing plants along the coast, as well as the resilience of the stock. The largest vessels outperformed the smallest, suggesting comparative advantage in coping with stock range changes.

Under the various harvesting scenarios, the area accounting for the majority of the catch and the surfclam dynamics are indicative of a realistic model behavior.  Our framework offers the opportunity to contrast management scenarios while accounting for more realistic fishery dynamics.