World Aquaculture December 2020

WWW.WA S.ORG • WORLD AQUACULTURE • DECEMBER 2020 39 thriving conch population but now only a few conch can be found. As a way to address the decline of queen conch, we set up a queen conch repopulation study within the MPA. The project was a partnership among Florida Atlantic University Harbor Branch Oceanographic Institute, The Exuma Foundation, The Bahamas National Trust and The Bahamas Department of Marine Resources. This project aimed to repopulate a historic conch habitat with conch translocated from spawning populations. Study Methods Moriah Harbour Cay National Park is located near George Town, Great Exuma, Bahamas (Fig. 4). We conducted a 12-wk study fromMay 26 to August 16, 2019 using a large circular enclosure 42 m in diameter and 76 cm high. It was installed by SCUBA divers in 2.5-4.5 mwater depth in a backreef area. Signs were attached to the enclosure to inform snorkelers that the conch inside the enclosure were part of a research project (Fig. 5). The enclosure encompassed sand and reef rubble areas as well as large areas of thick seagrass including Thalassia testudinum , Syrngodium filliforme , and Halodule beaudette (Fig. 6). This mixed habitat ensured that the conch that were translocated into the enclosure would have access to sufficient food resources. An effort was made to locate conch from nearby areas to stock the enclosure but insufficient numbers were found. Instead, conch were purchased from local fishermen (US$ 3.00 each) from their recent harvests. The fishermen collected these conch from fishing grounds about 100 km away from the research site. Because the conch were destined for market, the fishermen had knocked holes in their lips and strung the conch together in groups of five (Fig. 7). This practice helps fishermen to keep track of the conch during transportation and in the water prior to selling them. Once purchased, shell length of each conch was measured and a livestock tag was attached to identify each individual (Fig. 8). A total of 251 conch (47.5 percent male, 52.5 percent female) were stocked into the enclosure at a density equivalent to 1,813 conch/ha. Shell length ranged from 17 to 25 cm and lip thickness from 2 to 28 mm (Fig. 9). We visited the study site every 24-48 hours to observe behaviors such as movement, burial, grazing and reproductive activity. Visits to the enclosure also included monitoring for predation and maintenance on the enclosure. ( C O N T I N U E D O N P A G E 4 0 ) FIGURE 3. Queen conch egg mass (Photo: H. Forrest Thomas). FIGURE 5. The queen conch enclosure with signs (Photo: Megan Davis). FIGURE 4. Moriah Harbour Cay National Park study site near Great Exuma, The Bahamas (Illustration: The Bahamas National Trust). FIGURE 6. Habitat type overview inside the 1,400-m 2 enclosure. The excerpt map shows the location of the study site (Illustration: Laura Issac Norton, Map: Google Earth).