Connecting the Conchs in the Bahamas

Queen conchs (Lobatus gigas) are integral to the cuisine and the culture of the Bahamas. 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 is conducting research on the dispersal of this important snail to inform conservation and management strategies that will keep conch on the menu for future generations.

Adrift, then settled
Like many other marine species, queen conchs begin their lives as planktonic larvae that disperse on ocean currents. At about a month old, and as far as 100 miles from where they hatched, conchs end their larval journey and settle into shallow nursery habitats. Here the snails begin building the familiar spiked-and-spiraled shell and leading a considerably less mobile life.

Conchs take years to mature and reproduce. The best indicator of a conch’s age is the thickness of its shell. A conch with a shell 15 millimeters, or about half an inch, thick is likely reproductively mature. Unfortunately, many times conchs are legally collected by fishermen before they grow to that size. Reproduction, and therefore replenishment of conch habitats downcurrent, can’t happen if overfishing reduces the density of adults 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 where remaining adult conch populations are. Using Shedd’s research vessel as a basecamp in the Bahamas, they survey remote seagrass, hard-bottom and sand flat habitats to count conchs and measure 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 pulled by a small motorboat, they dive beneath the surface to count conchs and take photos to describe the ecosystem beneath them.

The next step is to determine dispersal pathways that link habitats where the researchers found conchs. While divers can’t follow microscopic larvae through the ocean, biophysical computer models can combine data about currents, seafloor topography and conch biology to simulate the movements of virtual larvae and predict potential planktonic pathways.

These data are passed along to conservation partners lobbying for management strategies supported by sound science. Our research is in partnership with the Conchservation Campaign, a group of not-for-profit organizations, spearheaded by the Bahamas National Trust, that are working together for a sustainable future for queen conchs.

Goal: Saving conch and eating it too
Queen conchs have been collected at a sustainable level 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. The fishery expanded and thrived for a couple of decades, but conch populations have since declined, and the fishery is overexploited in much of its range. Yet the demand for conch meat, and therefore fishing pressure, remains high.

So what is the solution? Our research will provide policymakers with data on population assessments, protected area efficacy and larval connectivity for queen conch in the Bahamas. Together, these data can be used to inform the future placement of a network of protected areas that exchange larvae and replenish stocks of conch and other species. Ultimately, we want a sustainable fishery that features a healthy population of conch both in the ocean and in the bellies of Bahamians.

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.