Connecting the Conchs in the Bahamas

Queen conch (Lobatus gigas) is at the heart of the Bahamas’ cuisine as well as its culture. Already depleted in much of the Caribbean and Gulf of Mexico, remaining queen conch populations in the Bahamas are near collapse. Shedd scientist Dr. Andy Kough will help inform the creation of protected habitats and development of a management plan for this important gastropod by describing the oceanic dispersal of tiny conch larvae.

Adrift, then settled
Like many other marine species, queen conchs begin their lives as planktonic larvae that are dispersed within ocean currents. At about a month old, and as far as 100 miles from where they hatched, they settle into seagrass bed sediments to begin building the familiar spiked-and-spiraled shell and leading a considerably less mobile life.

Conchs don’t reach reproductive age until they’re at least 3½ years old. Many times they’re collected by fishermen before that. Moreover, reproduction, and therefore replenishment of conch habitats downcurrent, can’t happen if overfishing reduces the density of conchs to the point where they can’t find each other to mate.

Mapping connectivity
If larval exchange is key to conchs’ sustainability, then knowing the dispersal pathways, or connections, among populations is key to their conservation.

To trace this connectivity, Andy and his team, which includes other researchers as well as citizen scientists, must first collect data on adult conch populations during the peak breeding season. Using Shedd’s research vessel as a basecamp in the Bahamas, they survey remote seagrass, hard-bottom and sand flat habitats to measure conch numbers and density. To cover a lot of ground quickly, the researchers use a method that’s a cross between snorkeling and sledding. Gripping the handles of a camera-equipped tow board that’s pulled by a small motorboat, they dive beneath the surface to take high-resolution photos that can be digitally pieced together into a mosaic map with crisp images of conchs, vegetation and other animals in the community.

The next step is to determine dispersal pathways. While divers can’t follow microscopic larvae through the ocean, computer tools can process data about currents, seafloor topography and movements of particles the size and shape of the larvae to create a biophysical model of those pathways. More fieldwork can confirm whether juvenile conchs are present in predicted areas.

Armed with this information, along with known fishing pressures, Andy can then recommend management strategies for the conservation of conchs. Andy’s research is in partnership with the Bahamas National Trust, Bahamas Department of Marine Resources and Community Conch, a not-for-profit organization dedicated to protecting the queen conch in the Bahamas.

Goal: Saving conch and eating it too
Queen conchs have been collected at sustainable levels by local subsistence fishers for centuries. Beginning in the 1970s, however, a commercial fishery developed for international markets, dominated by the United States, and for a growing tourist trade. Landings (the weight of the conch catch brought ashore) tripled within 20 years. Since then, landings have steadily declined as conch populations have been overfished, yet demand for conch meat remains high.

Creating a network of protected areas encompassing both where the larvae come from and where they settle, in tandem with implementing a science-based management plan, is a proven method of reestablishing healthy populations of benthic, or seafloor-dwelling, species. The connectivity study could inform the placement of new marine parks in the Bahamas. The parks would restock each other with new larvae, and as populations grew, an eventual overflow of adults into adjacent fishing grounds could once again support a sustainably managed harvest of the gastronomic gastropod aptly named queen conch.

Location

The Bahamas

About the team

Learn more about Dr. Kough and the conservation research team.

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About Dr. Andrew Kough
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. Read his full biography.