Queen conch, Lobatus gigas, is an iconic but threatened Caribbean species. The Bahamas are one of the last strongholds where conchs are still fished, but populations are in decline. The first step for protecting a species and replenishing its numbers is describing where healthy populations still exist and how they relate to disappearing populations.Our team of scientists used snorkel tow boards to efficiently count conch while collecting geolocated habitat imagery.
Earlier this month, a team from the Shedd Aquarium returned from an expedition down to the Sand Bores at the southern tip of the Tongue of the Ocean to survey for queen conch. This rugged and beautiful area has been largely uncharted since a visit by HMS ships Lark and Thunder in the mid-1800s and is still full of unknowns. The Shedd Aquarium’s research vessel, the Coral Reef II, was the perfect scientific platform for exploring the area. Our team of Shedd researchers, citizen scientists from Community Conch, Bahamian college students, and collaborators from the Smithsonian Institute and the University of Miami used snorkel tow boards (see photo on the left) to cover over 150 km of seafloor with georeferenced photography.
Now that we are back on dry land we are stitching these photos together into high resolution maps of our survey area, showing both animals and habitat. The tow boards let us cover a large area and helped us observe sporadically distributed animals in addition to conch, including marine mammals, elasmobranchs and Nassau grouper. The boards were also efficient at concentrating curious schools of large barracuda that would monitor our progress throughout their territory by swimming closely behind us and counting how many toes we had on each foot.
We documented that the ecosystem consisted of shallow rubble strewn bottom, vast expanses of oolitic sands, seagrass beds of varying density, patch reef, macroalgae flats and gorgonian plains. Most importantly, we found a thriving conch population with many happily mating aggregations of adults throughout the area, as well as juveniles and subadults distributed in the banks closer to deep water.
Unfortunately, there were also fishermen armed with traps, many illegal lobster casitas, an artifical cover board to congregate lobster, and plenty of harvested or “cracked” conch shells. Evidence of a concerted fishing effort, even over banks far from land, was a wake-up call to how timely and important conch research is in the Bahamas.
This was the first of several conch population surveys planned by Shedd in the Bahamas over the next few years. To supplement our habitat surveys, we also collected data on conch biometrics within the mating aggregations and took nonlethal samples for population genetics and the Smithsonian’s Global Genome Initiative. We plan on integrating these data to help Bahamians conserve conch into the future by providing the government with information on where conch are, and when we are not in the field, using models to describe where conch larvae may go. Together, we can use this information to better protect and preserve existing populations that may seed the next generation and keep conch in the Bahamas.
Andrew Kough joined Shedd Aquarium’s Daniel P. Haerther Center for Conservation and Research in 2015. Dr. Kough will lead fieldwork in the Bahamas to describe the larval journeys of queen conch (Lobatus gigas), an iconic but threatened species. His research focuses on the connectivity of declining conch populations and aims to uncover how otherwise separate habitats are linked by larval exchange. In partnership with a team of citizen scientists, Dr. Kough will survey previously undescribed conch populations throughout the Bahamas, taking measurements of adult population size and structure. These data will inform virtual models of queen conch larval dispersal that predict which populations exchange larvae and identify pathways of natural replenishment to better guide conservation planning. Dr. Kough earned his doctorate in marine biology and fisheries from the University of Miami, Rosenstiel School of Marine and Atmospheric Science. His dissertation research was on the larval connectivity of the Caribbean spiny lobster.