The giant hammerhead sharks (Sphyrna mokarran) are considered a migratory species, capable of traveling up to 3,000 kilometres. However, if the conditions in the area where they live are favorable, they may not embark on grand adventures.
A group of researchers studying these marine predators in the waters around Andros Island, the largest in the Bahamas, fitted sharks with tracking devices and observed that some individuals, instead of migrating to the eastern coast of the United States of America (USA) with the rest of the group, as would be expected, remain in the warm Caribbean waters.
Being the giant hammerhead sharks a species classified as “Critically Endangered” on the International Union for Conservation of Nature (IUCN) Red List of Threatened Species, scientists say that understanding the habitats they use is essential to protecting these large marine predators.
The scientists, in an article recently published in the journal ‘Frontiers in Marine Science’, led by the Saving the Blue organization, suggest that the absence of migratory behavior in some individuals (also known as philopatry) may be due to the fact that the environment they inhabit provides them with everything they need. Therefore, it becomes unnecessary to spend all the energy that would be required to swim hundreds of kilometres to reach another location with similar conditions, with all the risks that such a journey entails, including capture in fishing gear, the greatest threat to the species’ survival.
Thus, with abundant food and access to deep waters that remain cool even during the summer, the giant hammerhead sharks can stay, and some do stay, year-round in the Bahamas, where they find a sanctuary in which they can protect themselves from the threats that they would face during long migrations.
In addition to having documented this previously unknown behavior in Bahamian hammerhead sharks, the team verified, through analyses of tissue samples from some individuals, that two-thirds of their diet consists of rays and barracudas. The remaining third is made up of other smaller sharks.
