Abstract
The development of offshore wind structures in the northeastern U.S. will contribute to renewable energy goals, but will overlap with many marine species as well as economically important fisheries. High voltage transmission cables from offshore wind farms emit electromagnetic fields (EMFs) that elasmobranchs may detect using sensory organs known as ampullae of Lorenzini. However, sensitivity to EMFs varies by species due to differences in the number and arrangement of pores, the length of subdermal canals within the ampullae of Lorenzini sensory network, and the habitats they reside and regions they forage. For species who reside or forage in benthic regions, exposure potential to EMFs may be substantially higher than pelagic species due to proximity to the cables. This study quantified the vulnerability of two economically important elasmobranch species, smooth dogfish (Mustelus canis) and winter skate (Leucoraja ocellata), as a function of physiological sensitivity to electromagnetic fields and spatial exposure to the cables. The first ampullary pore maps were constructed for both species in order to better understand their potential sensitivity to EMFs. Using GIS, cable routes from offshore wind farms were overlayed with winter skate and smooth dogfish distributions to quantify: 1) the footprint of the transmission cables from each of the region’s offshore wind projects that overlaps with habitat of either species and 2) the proportion of both species’ geographic range within the study area that is potentially impacted by offshore wind development. Pore counts ranging from 1052 to 1924 indicate that M. canis has a relatively high resolution electrosensory system compared to other Carcharhiniformes. An average pore count of 476 in L. ocellata indicates a lower resolution. Offshore wind cable placement off the coasts of New York, Rhode Island, and Massachusetts are within regions of high biomass for both species. Nearly 27% of fall 2015-2019 M. canis distribution was intersected by offshore wind transmission cables, indicating the species is likely at high risk for direct effects from EMFs. Spring and fall L. ocellata exposure is lower at 10% and 8% respectively, but proximity to the benthos suggests that true exposure to EMFs is likely higher than that of M. canis. Based on pore maps and GIS analyses, M. canis has both high sensitivity to electric fields and high exposure to OWF transmission cables, and L. ocellata has low sensitivity and high exposure.