Effects of Acoustic Tag Attachment on Jonah Crab Molting, Growth, and Mortality.

Zicari, Stephen¹, Allex Gourlay¹, Corinne Truesdale^2,3, Melissa Omand³, Godi Fischer⁴, Kelton W. McMahon³, Skylar R. Bayer¹, ¹Department of Biology, Marine Biology, and Environmental Sciences, Roger Williams University, Bristol, RI, ²Division of Marine Fisheries, Rhode Island Department of Environmental Management, Jamestown, RI, ³Graduate School of Oceanography, University of Rhode Island, Narragansett, RI, ⁴Electrical, Computer and Biomedical Engineering, University of Rhode Island, Kingston, RI

Jonah crabs (Cancer borealis) are distributed across the southern Rhode Island continental shelf but are fished by distinct inshore and offshore fleets. It is uncertain how often crabs migrate between locations, if at all, and the regulators of this emerging fishery need more population connectivity information to sustainably manage it. ROAM tags (RAFOS Ocean Acoustic Monitoring), which detect sound over a limited bandwidth (260 Hz) emitted by RAFOS sound source arrays, may allow scientists to track the movement of crabs over 10s km. However, it is not known how attaching these tags onto crab carapaces will affect crab molting, growth, and survival over short periods of time. To address these critical questions, we collected 41 wild-caught crabs during their molting season, 85 - 120 mm in carapace width (CW), and attached ROAM tags onto 19 individuals leaving 22 untagged. Over the 53 days of the experiment, eight crabs molted and survived: four tagged and four non-tagged individuals. Chi-squared tests showed no statistically significant difference in proportion of population molting between tagged and untagged crabs (p-value = 0.54), including chi squared tests excluding deaths (p-value = 0.81). Molted crabs with no acoustic tags showed a 24.6 ± 1.8% increase in CW, and tagged crabs that molted showed a 27.8 ± 6.5% increase in CW. These results lend confidence to future deployments of ROAM tags, which open up new opportunities to track benthic organisms that are not suitable to geolocation using conventional GPS-based tags that require regular surface intervals.