The tiger shark (Galeocerdo cuvier) is a large, far-ranging species that exhibits a variety of movement patterns depending on location and season. These sharks are managed by NMFS as part of the “large coastal” species complex under the Atlantic Highly Migratory Species Fishery Management Plan, but are occasionally observed far at sea and caught in pelagic fisheries. To investigate movements of tiger sharks, we tagged 26 individuals in Bermuda in late summer of 2009 and 2010 with fin-mounted “spot” satellite transmitters. Although a number of sharks made fairly rapid (~2 weeks) and straight-line moves from Bermuda to the Bahamas, other sharks followed meandering paths eventually reaching the Bahamas after several months. Several smaller individuals remained in Bermuda over the winter. Some sharks spent the winter months moving within relatively small, near shore areas within the Bahamas, and subsequently moved north into pelagic waters where they remained during summer months. Other sharks left the Bahamas a short time after arrival, moving into pelagic waters during winter months. Several individuals tracked over consecutive winters (>19 months) occupied similar wintering areas within the Bahamas. North-south seasonal movements for many sharks appeared to be related to water temperature, with the majority of time spent at 24-28oC. Most sharks demonstrated the ability to seamlessly shift between pelagic and insular habitats spending approximately equal time in both environments. Although movements vary substantially among individuals, tiger sharks demonstrate high mobility trophically connecting widespread and disparate marine ecosystems in the Western North Atlantic.
Available at: http://works.bepress.com/mahmood-shivji/16/