Date of Award

Spring 3-2023

Degree Type

Masters Thesis

Degree Name

Master of Science (MS)


Ocean Science and Engineering

Committee Chair

Dr. Eric Powell

Committee Chair School

Ocean Science and Engineering

Committee Member 2

Dr. Chet Rakocinski

Committee Member 2 School

Ocean Science and Engineering

Committee Member 3

Dr. Roger Mann


The Atlantic surfclam, Spisula solidissima, is a biomass dominant bivalve of the Northwestern Atlantic. The surfclam’s historic range extended from Cape Hatteras to Georges Bank, but recent decades of warming bottom water temperatures have caused the surfclam to shift its range to cooler waters north and offshore within the range of the ocean quahog, Arctica islandica. An ecotone now exists over much of the offshore range of the surfclam in which surfclams and ocean quahogs co-occur. Regulations prohibit fishers from landing both species in the same catch, limiting fishing to locations where the target species can be sorted on deck. Wind energy development on the US outer continental shelf will further restrict available fishing grounds. SEFES, a spatially-explicit model of the Atlantic surfclam fishery was used to run simulations of species overlap in conjunction with wind farm development scenarios to evaluate the consequences of fishery displacement. Model scenarios with less restrictive fishing penalties to allow on-board sorting of clams exhibited higher raw catch numbers but also greater reductions in revenue and increased cost after wind farm implementation. A 2021 at-sea survey sampling of the overlap region was also conducted with the purpose of mapping fishable concentrations of surfclams and ocean quahogs. Species overlap between surfclams and ocean quahogs is most prominent in the 40-55-m depth range where size and density of surfclams declines with decreasing temperature, indicative of newly recruited populations in offshore, cooler waters. This analysis emphasizes the potential for economic disruption of fisheries and highlights the need for regulatory changes to allow mixed catches and landings.