They’ve deciphered diversity in mako shark DNA and sequenced white shark genomes – who’s behind the conservation genetics at SOSF-SRC?

From coastal nurseries to offshore oceanic island aggregations, endangered scalloped hammerheads travel great distances throughout their range. These highly migratory sharks often cross international ocean boundaries where their protection level may change from country to country. Their extensive journeys and widespread distribution can make conservation efforts difficult, particularly when determining their population boundaries and areas of key conservation concern. Genetics research provides keys to better understanding and managing this species, and sharks in general.

The Save Our Seas Foundation Shark Research Center (SOSF-SRC) is studying the genetics of our oceans’ greatest predatory fish, with a focus on shark species that are endangered or otherwise threatened.

A major focus of the SOSF-SRC research is the application of molecular genomic techniques to investigate the biology and assist conservation of elasmobranchs. Photo by Justin Gilligan | © Save Our Seas Foundation

Studying shark DNA enables SOSF-SRC scientists to view elasmobranch populations holistically, including by identifying links between seemingly separate populations, determining genetic diversity, understanding shark behaviour and even identifying and tracing the species and geographic origin of tissue samples through the global shark-fin trade. The SOSF-SRC’s groundbreaking research on elasmobranch DNA contributes to policy and management for better protection of vulnerable shark species.

Part of the scalloped hammerhead’s range lies within marine protected areas, but these hammerheads often travel to areas where they experience severe pressure from overfishing. In order to protect sharks like these, fisheries managers need to look at the population genetic patterns globally. Studying genetic links between populations can illuminate the movement and breeding patterns of certain species to determine areas that are critical to conserve. Some species may have a wide range, but population genetics can reveal regional populations. This distinction can determine whether conservation efforts require regional or international approaches.

Scalloped hammerhead. Photo © Pelayo Salinas

The SOSF-SRC’s mission is to aid in the understanding, management and conservation of sharks and rays by conducting impactful targeted research. One of the SOSF’s three global centres, the SRC was established in 2012 and is located at Nova Southeastern University (NSU) in Florida, USA, where it also functions as one of the university’s academic units. Although it is based in Florida, the SOSF-SRC has a global reach and studies shark species all over the world. And, as part of a university, it considers educating students to be a big part of its mission. Students train and participate in cutting-edge shark research and educational opportunities. By incorporating education into its mission, the SOSF-SRC is ensuring that its legacy passes to a new generation of shark scientists.

The SOSF-SRC is located in Florida and was established at Nova Southeastern University in 2012. Photo © Save Our Seas Foundation

The SOSF-SRC is using its DNA research to tackle another massive conservation issue. Every year, millions of elasmobranchs are caught to fuel the global shark-fin trade. Shark fins are cut off and traded around the world for shark-fin soup. By the time the fins reach their destination, it can be incredibly difficult to determine what species of shark they came from, and where it was caught. This creates a nebulous policy landscape when trying to protect endangered species. It is very difficult to trace specific species, which means that many of them slip through the cracks unnoticed. The genetic testing of shark products can result in greater accountability in this industry.

Dr Mahmood Shivji, the director of the SOSF-SRC, pioneered a rapid DNA test that can determine a shark’s species based on a small tissue sample. He has been sent shark samples from all around the world to test and has accumulated a large collection of genetic material for various species. Working in collaboration with Dr Shelley Clarke, he provided the first insight into the massive volume and species composition of the secretive shark-fin trade. By using the rapid test on randomised samples of shark fin, he and Dr Clarke were able to determine which species are most vulnerable to illegal fishing and whether conservation methods are effective in protecting them. The ability to test market samples can add a level of accountability the industry has previously not seen. Since Dr Shivji’s lab pioneered these tests, they have become widely adopted for enforcement around the world.

Dr Shivji also works closely with fisheries managers to help regulate endangered and at-risk shark species. The shark-fin trade is a complex global issue that requires cooperation and treaties between countries, particularly when a shark’s range crosses international borders. This correlates closely with research into population dynamics, such as that of the highly migratory scalloped hammerheads. Understanding the extent of a species’ range can help to institute better regulations. Knowing what species of shark has been caught is one piece of the puzzle, but it’s another to know where the shark came from.

At the SOSF–Shark Research Center samples are analysed by scientists and students working in the lab. Graduate student, Cassandra Ruck, conducting genetics research on the oceanic whitetip shark.

The SOSF-SRC and collaborators at Cornell University have also been leaders in deciphering the entire genetic make-up (genomes) of endangered shark species, including the white shark, its close relative the shortfin mako and the great hammerhead shark, to understand their unique biological properties and population dynamics.

Alongside its shark genetics research, the SOSF-SRC, in collaboration with the NSU Guy Harvey Research Institute, is also using satellite tracking on a number of shark species to better understand how they migrate through their habitat. Conservation approaches will look very different for a species with high site fidelity, which occupies a small range, and one that is highly migratory. Understanding the migration patterns of highly mobile shark species will provide insight into how the sharks react to shifts and stressors in their environment, such as climate change, and how their migrations overlap with areas of intense fishing.

Tracking data, from tagged silky sharks. Captured from the interactive website: https://www.ghritracking.org/

In a large, multidisciplinary project, the SOSF-SRC and its international collaborators are tracking silky sharks from the Galápagos Islands and studying the population genetics of this heavily fished species in the Eastern Tropical Pacific. They followed the migration of Genie, a silky shark from the Galápagos, for more than 27,666 kilometres (17,190 miles) in just two years using a satellite tracker. While some silky sharks remain close to shore and can easily be protected by marine protected areas, other individuals, like Genie, travel great distances for foraging, breeding and/or other purposes. The ability to map out travel patterns for sharks like the Galápagos silkies helps scientists to identify other important areas to protect. Silky sharks are one of the most frequently caught species for their fins. Protecting them will rely on a multi-pronged approach with international cooperation. This all begins with understanding how silky sharks utilise their habitat and how much time they spend inside and outside current marine protected areas.

Silky Shark. Photo © Matthew During

The SOSF-SRC’s multidisciplinary approach will help illuminate the ways sharks wander throughout the oceans and how they can best be protected. Deciphering global movement patterns and genetic population dynamics will provide knowledge needed for collaborative international policy. The ability to test market samples of shark fins will help scientists track which species are frequently slipping through the cracks and where additional regulation may be needed. Technological advances are answering important scientific questions as well as sparking new ones. There is so much left to learn about these creatures, but the SOSF-SRC is steadily piecing together the hidden lives of sharks.