World Aquaculture December 2019

WWW.WA S.ORG • WORLD AQUACULTURE • DECEMBER 2019 31 Females of the Strombus genus usually copulate with several males in the wild and females are capable of storing sperm for several weeks (Bradshaw- Hawkins and Sander 1981, D’Asaro 1965). Females lay crescent-shaped, sand-covered egg masses that, depending on the Strombus species, can contain 76,000 to 485,000 eggs that hatch in three to four days (Shawl and Davis 2004). Free-swimming veliger larvae develop for two to three weeks while feeding on phytoplankton (Fig. 3). After metamorphosis, the now benthic (1.2 mm shell length) snails grow their shells and body mass. Once the “lip” of the conch flares, they will cease growing in shell length, begin to thicken their lip and become sexually mature, which can be one to two years for fighting conch (Davis pers. obs.) to four years for queen conch (Davis 2005). Conch egg masses in the wild can sometimes be difficult to find, so establishing a captive breeding program in the laboratory or in an enclosure in the wild can be a solution to guarantee reliable egg production (Davis et al. 1984, Shawl et al. 2005). Several species of the Strombus genus, including queen conch ( S. gigas ) , Florida fighting conch ( S. alatus ) , milk conch ( S. costatus ) and hawk- wing conch ( S. raninus ), have mated and produced egg masses in captivity in a recirculating system at HBOI (Shawl and Davis 2004). Larvae from these captive-laid egg masses were cultured through the juvenile stage. A follow-on study conducted at HBOI looked at reproductive output of Florida fighting conch stocked at different sex Overview The fighting conch Strombus alatus (Linné, 1758) is found on Florida’s Atlantic and Gulf coasts (Perry and Larsen 2004). This medium sized (7-10 cm shell length) herbivorous gastropod (Fig. 1) breeds in shallow waters in seagrass beds, typically during summer, when they form spawning aggregations. They are closely related to the popular commercial fisheries species queen conch Strombus gigas (Fig. 2). Both species have similar characteristics in terms of biology, development, taste and meat appearance (Davis and Shawl 2005, O’Dea et al. 2014). Fighting conch has been a subsistence food source among coastal people of the Caribbean and Gulf of Mexico (O’Dea et al. 2014) but it has potential to be a suitable species to supplement the queen conch food market if it can be grown in sufficient quantity by the aquaculture industry. This species has qualities that make it a good candidate for seafood aquaculture and aquariummarkets (Davis and Shawl 2005). In the 2000s, fighting conch were successfully cultured in large numbers (50,000-100,000 per year) for the aquarium trade at Harbor Branch Oceanographic Institute (HBOI) based on techniques used to culture queen conch (Davis 2005, Davis and Shawl 2005). Florida fighting conch breeds in captivity, grows fast, is tolerant of variable water quality and is not a protected CITES species like queen conch (Shawl and Davis 2004, Davis and Shawl 2005, Shawl et al. 2005). Reproduction and Development Adult conch have separate sexes and internal fertilization. Aquaculture of Florida Fighting Conch for Seafood and Aquarium Markets Megan Davis and Yanelys Cantillo Villa ( C O N T I N U E D O N P A G E 3 2 ) FIGURE 1. Adult Florida fighting conch Strombus alatus . Photo: Tom Smoyer. LEFT, FIGURE 2. Queen conch Strombus gigas . Photo: Megan Davis. RIGHT, FIGURE 3. Florida fighting conch veliger larvae with six lobes. Dots on the ends of lobes are characteristic of fighting conch veligers. This veliger is approximately 21 days old and competent for metamorphosis. Photo: Megan Davis.