WWW.WAS.ORG • WORLD AQUACULTURE • MARCH 2015 53 Silver sillago Sillago sihama (Fig. 1), a member of the family Sillaginidae, is distributed throughout the Indo-West Pacific Ocean, occurring from southern Africa to Australia, the Arabian Gulf, the Red Sea and Mediterranean Sea. It is found along shallow sandy and muddy inshore waters and mangrove creeks. It is a planktonivore that preys predominantly on diatoms, bluegreen algae, dinoflagellates, polychaetes, a variety of crustaceans, mollusks and, to a lesser extent, echinoderms and fish. It burrows in the sand and mud in search of food and to escape from potential predators. In the United Arab Emirates (UAE), the fish is known as hasoom and it is a common species in local fish markets. The fish is a gonochoristic species, reaching sexual maturity at 13-16 cm in length, corresponding to about 1 to ≥ 2 years of age. It has a protracted breeding season from June to February, with peaks of spawning activity from December to February. Females release several hundred thousand eggs, which are small spherical, pelagic and transparent. The onset of gametogenesis occurs during October and November (Mckay 1992, Carpenter 1997, MAF 2003, Khan et al. 2013, 2014). The results of the first spawning, larval rearing and growing of this species in the UAE at the Aquaculture and Marine Studies Center (AMSC), Abu Al Abyad Island, Abu Dhabi are presented in this article. Broodstock Management Silver sillago breeders with an average length of 15 cm and average weight of 25 g were collected from the Al Hanyoorah Spawning, Larval Rearing and Growth of the Silver Sillago in Abu Dhabi Omer M. Yousif, Krishnakumar K. Menon and A-Fatah A. A-Rahman area, northeast of Abu Dhabi and brought to the AMSC where they were dipped in freshwater for 2 min to control external parasites and then stocked in a 40m3 concrete circular tank with 45 ppt seawater (Fig. 2). Fish were fed a diet of squid, sardines, shrimps and pelleted feed (52 percent crude protein). Spawning, Incubation and Hatching Natural spawning was first observed in January 2013. Subsequent to the first spawn, four more spawns were obtained until the end of February 2013. The total number of eggs was 192,000, of which 94 percent were fertilized. Eggs were small and spherical, averaging 714 μm (690-750 µm) in diameter. Fertilized eggs were buoyant and thus skimmed from the water surface with a 100μm mesh dip net (Fig. 3), rinsed with fresh seawater, separated and counted with a graduated cylinder. The volumetric density of eggs was estimated at 2,400 eggs/ mL. Fertilized eggs were transferred to 600-µm mesh incubation baskets at 4-5 eggs/mL. During incubation, water temperature ranged from 22-23 C. Eggs hatched within 26 h and the hatching rate was 56 percent (Fig. 4). Larval Rearing and Grow-out Newly hatched larvae, measuring 1.64 ± 0.16 mm, were transferred to 4-m3 larval rearing tanks (LRTs) at 25 larvae/L. In the first two days post-hatch (ph), larvae in all LRTs were held in (CONTINUED ON PAGE 54) FIGURE 1. The silver sillago Sillago sihama, known locally in Abu Dhabi as hasoom. FIGURE 2. Stocking silver sillago broodfish in a 40-m3 tank. FIGURE 3. Skimming floating eggs of silver sillago.
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