An apex predator, tiger sharks (Galeocerdo cuvier) are a widely spread shark species. In addition to their oceanic roving nature, the striped skin creatures also inhabit coastal regions, including coral reefs and atolls. Near Little Bahama Bank, a shallow region of water has become a hotspot for female tiger shark activity, so much so that the area was nicknamed Tiger Beach. Research into the area has revealed that females spend prolonged periods of time in the area (up to 180 days).
Researchers from the University of Miami and the University of New England recently performed a multi-year, multi-season study of the region’s female tiger sharks to understand their gestation habits. The study, published in February in Aquatic Biology, made use of the same imaging technology used by medical professionals on pregnant women.
“Although lethal sampling has historically been considered the most effective approach for collecting reproductive information from elasmobranch fishes, non-lethal approaches such as ultrasonography and analysis of plasma sex steroid hormones have become feasible and/or practical sampling alternatives,” the researchers wrote in their paper.
Between 2011 and 2014, the researchers recorded the reproductive status of 59 female tiger sharks.
“Our results indicate that Tiger Beach is a high-use site for the female tiger sharks of mixed life stages,” the researchers wrote. And “also suggests that Tiger Beach may function as a refuge habitat, allowing females to reach maturity free from male mating harassment, as well as functioning as a gestation ground where gravid females can benefit from year-round calm warm waters, which may reduce the gestation period and accelerate embryo development.”
This information is critical for conservation. Though Tiger Beach is located in the Bahamas Exclusive Economic Zone, which protects it from shark fishing, tiger sharks and other migratory marine predators are facing decline across the globe, according to the Univ. of Miami.
“Although the results of this study suggest that Tiger Beach is occupied by sharks of mixed life-history stages, it is not known how long or to what extent individuals utilize Tiger Beach or the protected Bahamian waters,” the researchers wrote. “If gravid females spend little time within the sanctuary and/or give birth outside the sanctuary, they may be vulnerable to exploitation when they leave the area.”
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