Is the tiger shark Galeocerdo cuvier a coastal species? Expanding its distribution range in the Atlantic Ocean using at‐sea observer data

Abstract

The occurrence of tiger shark Galeocerdo cuvier in the Atlantic Ocean was assessed using at-sea observer data from multiple pelagic longline fisheries. Geographic positions of 2764 G. cuvier recorded between 1992 and 2013 and covering a wide area of the Atlantic Ocean were compared with the currently accepted distribution ranges of the species. Most records fell outside those ranges in both the Southern and Northern Hemispheres, which strongly suggests that the distribution range of G. cuvier in the open ocean is considerably larger than previously described.

A new map of the tiger shark (Galeocerdo cuvier) genetic population structure in the western Atlantic Ocean: Hypothesis of an equatorial convergence centre

“…Possible reasons for tiger shark movements around or towards Fernando de Noronha Archipelago might include: (a) 70% of the insular shelf is a marine protected area, which has extensive reef formations that harbuor an abundant fish fauna, and it is also used as a breeding ground for several reef and pelagic fishes, marine turtles, reef‐dwelling elasmobranchs, and seabirds (Conference of the Parties to the UN Convention on Biological Diversity 2012), representing an equatorial Atlantic offshore prey's oasis; (b) telemetry satellite data demonstrate that tiger sharks tagged in Fernando de Noronha can either travel west to the South American continent or move across the Atlantic basin towards Africa (Afonso et al, ); (c) detailed onboard observer data from multiple Atlantic fishing fleets suggest that tiger sharks may use equatorial latitudes as a connecting corridor to perform transoceanic migrations across the Atlantic (Domingo et al, ); (d) those transoceanic movements along the equatorial Atlantic might be bidirectional, from the Americas to Africa and vice versa, given the complex current and counter‐current system of this region (Stramma, ); and (e) genetic evidence suggests that the south‐western Atlantic Ocean was likely a historical connection linking tiger shark populations from the Atlantic and Indo‐Pacific via dispersal around South Africa (Bernard et al, ; Naylor et al, ). Thus, there seems to be a high possibility that tiger sharks migrating to the northern and southern Western Atlantic converge on Fernando de Noronha Archipelago for foraging or simply because the area is the closest route in the equatorial region.…”

“…Tiger sharks are captured in many fisheries as bycatch and the species is currently listed as Near Threatened by the International Union for Conservation of Nature Red List (Simpfendorfer, ). The tiger shark is a widespread species that demonstrates home range behaviour over large spatial and temporal scales (Domingo et al, ; Papastamatiou et al, ). Tiger shark populations comprise, at least in part, individuals that maintain large territories and return to specific areas on a regular basis (Bernard et al, ; Heithaus, ; Lea et al, ).…”

Genetic population structure and demography of an apex predator, the tiger shark Galeocerdo cuvier

“…Data from pelagic longline fisheries have highlighted the importance of the pelagic realm to a species originally described as coastal (Domingo et al., ; Polovina & Lau, ). More recently, tiger shark individuals have been recorded moving over several thousands of kilometers distances (Ferreira et al., ; Hammerschlag, Gallagher, Wester, Luo, & Ault, ; Holmes et al., ; Lea et al., ; Werry et al., ), including crossing ocean basins (Afonso, Garla, & Hazin, ; Heithaus, Wirsing, Dill, & Heithaus, ; Kohler, Casey, & Turner, ; Kohler & Turner, ).…”

A Perspective on Future Tiger Shark Research

“…Satellite telemetry (Lea et al, 2015;Meyer et al, 2018) and catch records (Polovina and Lau, 1993;Domingo et al, 2016) show tiger sharks make offshore migrations in both the Pacific and Atlantic. Adult tiger sharks in the Atlantic undertake repeated annual migrations which track latitudinal shifts in sea surface temperatures (SST) (Lea et al, 2015(Lea et al, , 2018.…”