Understanding impacts of the sea scallop fishery on loggerhead sea turtles

Project leads: Samir Patel and Liese Siemann

Collaborator: Heather Haas, NEFSC Protected Species Branch

Funded by: NOAA Sea Scallop Research Set-Aside

Sea turtles are long lived species that on a yearly basis can exhibit high levels of behavioral plasticity. To determine accurate trends for these species, particularly in the context of fisheries interactions, larger sample sizes and long-term studies are required. This project has accrued one of the largest datasets from in-water sampling of sea turtles at a foraging ground, a particularly rare and difficult approach to studying these animals, allowing us to examine the distribution and behavior of loggerhead sea turtles in order to better understand sea turtle interactions with the scallop fishery and reduce sea turtle bycatch. We have been able to identify spatial and temporal “hot spots” on the fishing grounds, as well as turtle behaviors that impact bycatch rates. Over the past ten years of data collection, CFF and its partners have used a variety of techniques to study loggerheads, including satellite telemetry, in-water videography, morphometric measurements, and blood and tissue sampling. Each year we discover new behaviors and face unexpected challenges that limit our ability to develop trends. For example, we are starting to notice a shift in seasonal behavior, with turtles spending more time in the Mid-Atlantic Bight (MAB) beyond the date range (May – Oct) required for use of turtle chain mats and the turtle-deflector dredge. In a companion project funded by the Saltonstall-Kennedy grant program, we projected loggerhead distribution based on sea surface temperature and determined that this trend will likely continue, with loggerheads arriving earlier in the MAB and moving farther north into scallop fishing grounds in Southern New England and on Georges Bank, expanding risks to turtles from the scallop fishery.

Sea Turtle out of the net  Kathy Ann 5.2

Release of a loggerhead after affixing a satellite tag (ESA permit 18526).


Still image from ROV footage of a loggerhead walking along the sea floor (ESA permit 18526).

turtle surfacing v SST.jpg

Satellite tag data can be used to look at the relationships between turtle behavior and environmental parameters. This plot shows the relationship between sea surface temperature and time turtles spend on the surface.