Dean’s research is focused on the biology and ecology of the smalltooth sawfish, and he concentrates his efforts around the island of Andros in the Bahamas. As the largest island in the Bahamas, Andros is the least densely populated and its remote west side is nearly pristine. Dean collects blood from smalltooth sawfish to assess reproductive status, muscle samples for food web analyses and fin clips for genetic studies. He tags each sawfish, which is then tracked by satellites and acoustic receivers, to know more about where these animals move, what they do and how best they can be conserved.
I am a fish ecologist with interests in the biology of exploited and poorly studied estuarine and marine taxa. Much of my research addresses specific biological gaps necessary for the management and conservation of coastal and deep-water sharks and rays, including research on endangered smalltooth sawfish. My interest in sharks stems from being raised fishing and exploring Florida’s Gulf coast. I received Bachelor’s degrees in marine science and biology from the University of Miami and a PhD in fisheries science from the College of William & Mary’s Virginia Institute of Marine Science. I was a post-doctoral researcher and faculty member...
Our primary goal is to conduct research that supports and promotes the recovery of the Critically Endangered smalltooth sawfish in The Bahamas. Our objectives are to determine the population size and viability of this sawfish population, to assess the probability of recovery and to determine what habitats are critical to its continued survival.
Sawfish are among the most imperilled of all families of sharks and rays. All five species in the group are currently listed as Endangered or Critically Endangered. The Critically Endangered smalltooth sawfish is endemic to the Atlantic basin and its only known viable populations are in the USA and The Bahamas. Our research seeks to address questions and provide data that assist efforts to promote the recovery of this iconic species.
Sawfish include five living species of very large rays and all are listed as Endangered or Critically Endangered according to the IUCN Red List of threatened species. Sawfish have a large toothed rostrum that is used for defence and immobilising prey, but it also makes them vulnerable to fishing nets. The smalltooth sawfish is found only in the Atlantic and the USA supports the most robust population of the species, although it has declined severely due to overfishing, including harvest for the rostra (which are sought as curios), and habitat loss. In 2003, the smalltooth sawfish became the first marine fish listed as Endangered under the US Endangered Species Act. Our research suggests that a reproducing population of smalltooth sawfish exists also in The Bahamas, primarily on the western side of the island of Andros. With SOSF support, in 2016 we were the first to ever witness the birth of baby sawfish, thus confirming that sawfish give birth in Andros. Our tracking data from sawfish tagged in the USA and The Bahamas suggest that these populations are isolated and their recovery may be critical to the recovery of the species. For this reason, the IUCN Shark Specialist Group has designated the US population a ‘Lifeboat’ and The Bahamas’ population a ‘Beacon of Hope’ in its 2018 ‘Saving sawfish: progress and priorities’ update. The western side of Andros is remote and pristine and much of the sawfish habitat lies within Andros West Side National Park. Our data suggest the sawfish population in Andros is much smaller than that of Florida, despite the habitat being comparable. This may be due to differences in protective habitat, available food, density of sharks that compete for food or the number of predators that feed on young sawfish. We seek to unravel these mysteries to assess the likelihood of recovery of The Bahamas’ sawfish population.
Key challenges to sawfish conservation are the ability to estimate and monitor changes in population sizes and to identify habitats critical to survival and recovery. We seek to determine the relative size of the Bahamian smalltooth sawfish population compared to the US population, to define habitats that are critical to survival (such as nursery habitats) and to examine ecological processes that influence changes in The Bahamas’ smalltooth sawfish population. We will use our baited line surveys and records of sawfish sightings to estimate the relative abundance of smalltooth sawfish and coastal sharks that serve as competitors or potential predators to the sawfish. We will examine the overlap between sawfish and sharks in the Andros food web, as a proxy for determining shark species that may compete with sawfish for prey as well as those that may prey on juvenile sawfish. Smalltooth sawfish will be implanted with long-term acoustic transmitters that, along with previously tagged sawfish, are detected by existing SOSF-sponsored acoustic receiver arrays in Andros and Bimini. These data will be used to monitor sawfish residency and long-term movements and migrations as functions of temporal and spatial fluctuations in variables such as tidal cycles and salinity over days, seasons and years. This will also allow us to monitor how often adult females return to known habitats to give birth. We will use blood samples to determine whether females are mature and reproductively active. Genetic material from adult female and young-of-year sawfish will be used to potentially link offspring with their mothers and determine how frequently females return to give birth. In addition, our data will provide baseline information concerning primary sawfish habitat should development take place that affects the habitat negatively.
Anna is collecting genetic information from white shark fin clips to assess this species’ population size in South Africa. Using close-kin mark-recapture analysis instead of traditional methods, she hopes to provide an accurate account of South Africa’s white shark population size. She also aims to develop a monitoring protocol that can use genetic samples collected during shark net and drumline patrols by the KwaZulu-Natal Sharks Board. This information is needed in South Africa, where the conservation of a protected species is balanced against concerns about bather safety, and where sharks are caught in bather protection gear.
Faqih is filling the gaps in the scant knowledge of giant guitarfish in Java’s Karimunjawa National Park marine protected area (MPA). Karimunjawa is located near Northern Java’s main fishing grounds, but evidence of giant guitarfish caught in some of the use-zones of the MPA hints that the park may be a sanctuary for the species. Managing giant guitarfish in Karimunjawa requires species-specific information.
Faqih’s project is a socio-ecological one to help inform management and draws on new information about relative abundance and distribution, historical occurrence and fishing pressures to paint a contemporary picture of the species in the park.
Cindy wants to know if bonnethead sharks in the Eastern Pacific constitute a third, cryptic species. The Bonnethead complex need clarification in all its distribution range, and Panama is a key country to solve this question since we have the Caribbean sea and the Pacific Ocean. By collecting fin clip samples to compare species at the genetic level and collecting specimens to compare how they look (morphology), Cindy hopes to resolve the taxonomy of Sphyrna tiburo vespertina – that is, whether it’s a cryptic third species for bonnetheads in the region. Her information can help update the IUCN Red List for bonnetheads and improve fisheries policies in Latin America where bonnethead sharks are commonly caught.