Overview

Adequate conservation and management of shark populations is becoming increasingly important on a global scale with declines documented worldwide. Successful management of these species requires detailed information on their movement and distributions. However, generating such information for large-bodied sharks is challenging, as they typically move over long distances, are logistically difficult to capture and, as upper-trophic predators, are naturally low in abundance. The three species of the large-bodied hammerhead complex, i.e. great, scalloped and smooth hammerheads, epitomize such challenges, they are target or bycatch species in a variety of fisheries, and as a result, substantial population declines have occurred in many areas. In the U.S. Atlantic all three species are caught in commercial fisheries, however due to their sensitivity to capture (i.e. high at-vessel mortality) reducing quotas or prohibiting landings will not decrease mortality. Thus, alternative methods for their management are urgently needed. In the Bahamas they are protected via the Shark Sanctuary, however little is known about how they use the Bahamas Archipelago. Some research on great hammerheads indicates seasonal residency to islands during the winter months, but Andros Island with its expansive, unaltered habitats offers a year-round, abundant source of food. This research will use a variety of scientific tools, from animal trackers to chemical analysis to examine the movement behavior and ecological role of both species, identifying key habitats, migratory pathways, determining spatio-temporal overlap with fisheries and ultimately generating key data for their improved management and protection.

Conservation concern

Great, scalloped and smooth hammerheads are large-bodied and highly-mobile shark species that fulfill the role as apex predators throughout their range and as such are important for ecosystem stability and functioning. However, due to these species being a target or bycatch species in global fisheries, they have experienced substantial population declines throughout their range. This has led to the species being listed on the Convention on International Trade in Endangered Species (CITES) Appendix II in 2013. Further, great and scalloped hammerheads were listed on the Convention on the Conservation of Migratory Species of Wild Animals (CMS) Appendix II in 2014 and smooth hammerheads were added to Annex I of the CMS Memorandum of Understanding for migratory sharks in 2018. Additionally, scalloped hammerhead sharks were the first shark species protected under the U.S. Endangered Species Act. Subsequently hammerheads were identified in 2017 as a priority group that would benefit the most from improved management. Strategies to reduce the risk of interaction with fisheries, bycatch mortality and increase the post-release survival are needed for all three species and an improved understanding of their movement ecology can help us in making management as efficient and as well-informed as possible.

habitat, space and resource use of the great hammerhead shark

Movement ecology of the large-bodied hammerhead complex with implications for management of great, scalloped and smooth hammerheads in the North Western Atlantic

To gain an insight into our Jupiter work you can watch two short videos HERE and HERE.

Seasonal movements and residency of scalloped hammerheads to and from underwater seamounts in the Gulf of California and off the Southern coast of Mexico