Fish aggregating devices (or FADs) are used by tuna fishers globally to attract shoals of their target species. Unfortunately, highly threatened and social silky sharks also form large aggregations – often near these floating attractions in the ocean. Bryan wants to know what’s driving these aggregations to form near FADs. He hopes that by uncovering this information, this project will help inform fisheries managers on suitable ways to mitigate silky sharks being killed near FADs when they are caught as tuna bycatch.
Animals have fascinated me since I was young. I remember gazing at sharks whenever I visited aquariums and I would sometimes ask questions that had yet to be answered. This motivated me to carry out research that would provide answers to my questions, as well as scientific insights into our friends in the sea. After earning my BSc from the University of Arizona I was able to begin my own research.
For my MSc I studied the social behaviour of lemon sharks at the Bimini Biological Field Station and then earned my PhD from Florida State University, where I studied...
To assess how environmental parameters and the social behaviour of the silky shark affect aggregation dynamics and habitat use near fish aggregation devices (FADs); and to provide fisheries managers with these data to better inform mitigation measures, which could lead to a decrease in bycatch of the species globally.
The silky shark has been identified as one of the shark species most vulnerable to overfishing and the bycatch of silky sharks near FADs has resulted in population declines around the world. The recognition of this issue is timely in view of the fact that the use of FADs is increasing rapidly. Our research will contribute to preventing the extirpation of silky sharks from fishing hotspots and will assist the global recovery of the species.
The silky shark is found worldwide, typically in tropical oceanic waters near continents or islands. Like many elasmobranch species, it grows slowly, reaches maturity late and has relatively few young. It is also highly social and often forms large aggregations, many of which unfortunately occur around FADs, devices that are used by fishers around the world to target tuna species. This association with FADs and the species’ conservative reproductive traits make the silky shark one of the shark species most vulnerable to overfishing.
Silky sharks represent more than 90% of shark bycatch in the fisheries that use FADs. The goal of our work is to conduct research that will help to reduce the global bycatch of the species. Many scientists have studied silky sharks and FAD use. We know that the sharks exhibit strong ties to these floating objects and that diel cycles contribute to this association. Given the strong social nature of silky sharks, other research has highlighted the importance of including social behaviour in studies of FAD use.
Our project addresses this scientific gap by including social behaviour in aggregation and habitat use models. We will use acoustic telemetry, with an innovative analytical model, to study the social structure of silky sharks and assess how environmental parameters and this sociality affect aggregation dynamics and habitat use. We hope to provide habitat managers with more robust information for protecting silky sharks. For example, we could find that juvenile silky sharks are more likely to aggregate near FADs at different times compared to mature adults. The overall goal of this research is to provide habitat managers with the data necessary to produce fisheries management plans that would reduce the global bycatch of the species.
Outside the USA, The Bahamas is the only place where Critically Endangered smalltooth sawfish can reliably be found. Tristan wants to ensure that protection measures in The Bahamas are understood and enforced as far as sawfish are concerned to close the current gap between policy and the people. He’ll be using aerial surveys, sonar and BRUVs, combined with interviews that draw on local knowledge, to identify essential sawfish habitats that need protection. Engaging with the community through workshops and by training students and meeting with government, Tristan intends to advocate for smalltooth sawfish protection throughout The Bahamas’ territorial waters.
Steven and Kevin are using genetic techniques to understand how Caribbean reef shark populations are connected across the extent of their range. Populations of this Endangered shark are in decline generally, but where they are managed and there is effective protection, their numbers are stable. With the integration of the correct information, Steven and Kevin are convinced that we can give Caribbean reef sharks a better shot at recovery and population stabilisation. They will also explore any barriers to connectivity, looking to the future recruitment and recovery of these sharks.
With very little information available about Endangered sicklefin devil rays, their seasonal aggregations at sea mounts in the Azores give Sophie an opportunity to learn more about their lives. She will be collecting satellite-tracking data that show how they move in the Azores’ exclusive economic zone. The information she collects will be used to develop maps of how the rays are using the zone and to identify essential areas that multiple species use. With this information at hand, Sophie hopes her work can contribute to a network of marine protected areas.