World Aquaculture December 2020

38 DECEMBER 2020 • WORLD AQUACULTURE • WWW.WA S.ORG before laying an egg mass. These masses are typically laid in coarse sand and reef rubble but can also be laid in seagrass beds (Fig. 3). Each conch egg mass holds close to 500,000 microscopic eggs, each smaller than a grain of sand. After eggs incubate, they hatch into pelagic veligers, drift with currents for 2-4 weeks and metamorphose into benthic snails in seagrass habitats. Areas where conch metamorphose are described as “ecologically unique” because nearby, seemingly similar areas are less suitable as conch habitat. Juvenile conch feed on epiphytes growing on seagrass blades. Conch reach sexual maturity in four years when they have a fully developed shell lip with a thickness of 15 mm or more. Conch have many predators during their life cycle. As pelagic veligers, they are prey for planktivores. As benthic juveniles, they are prey for sharks, sea turtles, stingrays, lobsters, fish, hermit crabs and carnivorous snails. As adults, the heavy shell of the conch provides protection frommost predators but they are still susceptible to predation by octopuses. Queen Conch Repopulation Study in The Bahamas Many researchers have suggested that using a network of Marine Protected Areas (MPAs) can serve to replenish species and provide a refuge from fishing pressure. The Bahamas National Trust has been establishing MPAs known as National Parks since 1959. Some of these Parks encompass conch breeding grounds, such as the Exuma Cays Land and Sea Park. This Park was established in 1958 and has a large population of adult queen conch that have been successfully protected. Moriah Harbour Cay National Park is a more recent MPA, established in 2002. According to local Bahamians, this Park historically had a Background In the crystal blue waters of Florida, The Bahamas and the Caribbean lives a keystone herbivore species in need of saving: the queen conch Aliger gigas (formerly Strombus gigas ) (Fig. 1). These iconic gastropods spend their days grazing in shallow seagrass beds and sand flats, helping to keep the ecosystem clean and in balance. They are economically valuable throughout the Caribbean for culinary delicacies such as conch salad, chowder and fritters, and for their beautiful pink-lipped shell and rare pearls. Conch have been heavily fished for decades, leading to a Florida conch fishing moratorium in 1985 and a number of other regulations throughout the Caribbean. In 1992, the species became a managed fishery as part of the Convention of International Trade in Endangered Species of Flora and Fauna (CITES) Appendix II. However, this listing, along with local regulations, have not been enough to slow the decline of the species. In a recent study, researchers found that, without changes in fishery practices, commercial conch stocks in The Bahamas may be depleted in 10- 15 years (Stoner et al. 2019). The citizens of The Bahamas and the Caribbean are concerned about access to this cultural food staple but the decline is most alarming for fishermen, whose traditional livelihoods are at stake, and for ecological balance in seagrass beds. Queen Conch Life Cycle The life cycle of the queen conch starts with internal copulation during the summer breeding season (Davis 2005, Fig. 2). For this to take place, conch must be at a density of at least 100/ha to find partners (Stoner et al. 2019). Females can mate with multiple males Return of the Queen: A Queen Conch Repopulation Study in The Bahamas Laura Issac Norton, Megan Davis and Catherine Booker FIGURE 1. Native geographic range of queen conch (Illustration: Bonnie Bower Dennis). FIGURE 2. Queen conch life cycle (Illustration: Bonnie Bower Dennis).