WWW.WAS.ORG • WORLD AQUACULTURE • SEPTEMBER 2016 39 The orange-spotted grouper Epinephelus coioides, locally known as hamour, is a member of the family Serranidae and is distributed throughout the Indo-West Pacific from the Red Sea and Arabian Gulf to South Africa, eastward to Palau and Fiji, north to the Ryuku Islands and south to the east coast of Australia and southern Japan. In the United Arab Emirates (UAE) the species is widespread throughout the entire coast line occurring in shallow waters down to 100-m depth. It is a carnivorous fish that feeds on fish and crustaceans. Like other serranid species, it is a protogynous hermaphrodite, maturing first as females at around 3-4 kg body weight, corresponding to 2-3 years of age. Some of the fastest growing females later transform into males when they reach a body weight of more than 6 kg (Abdessalaam 2002, Yousif et al. 2016). In the UAE, hamour is the food fish in greatest demand and Fingerling Production of Orange-Spotted Grouper on Abu Al Abayad Island, United Arab Emirates Omer M. Yousif, Krishn Akumar, M. Balamurugan, V. Hozifa and A. Sagir correspondingly fetches the highest price in the local market. However, there has been a significant decline in natural stocks from severe over-exploitation in UAE waters over the last few years, as indicated by decreased landings. It is estimated that this species is being exploited at a level of up to six times the sustainable limit (Grandcourt et al. 2005, Choat et al. 2015). The high market demand and reduced natural supplies of the orange-spotted grouper make this species the top potential candidate for aquaculture in UAE. To support the development of hamour aquaculture in Abu Dhabi, the Aquaculture and Marine Studies Center (AMSC), located on Abu Al Abyad Island, made a trial to produce fingerlings of this species, which is the major bottleneck hindering development of commercial grouper aquaculture in the area (Ma et al. 2013). The results of broodstock management, spawning, larval rearing and nursing of this species are presented in this article. Broodstock Management and Spawning Fifty-two adult broodfish from 3.5 to 14.0 kg were collected from the channels surrounding Abu Al Abyad Island and were stocked in 5 × 5 × 2.5 m net cages located in one of these channels near the AMSC. Broodfish were given a freshwater bath for about 3 min before stocking in the net cage. During two years in net cages, broodfish were fed daily with fresh sardines, squid and crabs to satiation. Beginning January 2016, fresh feeds were fortified with vitamin E and fish oil every other day. On 15 March 2016, fish were checked by cannulation and only ripe females with oocytes ≥ 490 µm in diameter and ripe males with running milt were selected and transferred to 40-t, indoor, oval spawning tanks at 8 fish/tank (4♀:4♂). Broodfish were gradually acclimated to 35 ppt seawater over four days by adding fresh water to the natural seawater of the island (50 ppt). During this acclimation period and throughout the spawning period, broodfish were fed fresh squid and crabs daily to satiation. No hormone injection was applied and all fish were allowed to spawn naturally. Buoyant eggs averaging 847 μm (824-864 μm) in diameter were skimmed from the water surface 12 h after spawning, rinsed, separated and counted as described by Yousif et al. (2012). Fertilized eggs were then directly transferred to 600-μm mesh cylindrical incubation baskets placed in larval rearing tanks at 20 eggs/L. The first batch of fish spawned from 30 March to 8 April and the second batch from 12 April to 7 May. The total number of females spawned was 20 females yielding 22.33 million eggs, of which 12.01 million (54 percent) were fertilized. The average hatching rate was 30 percent, resulting in 3.60 million newly-hatched larvae (Table 1). TABLE 1. Spawning performance of orange-spotted grouper in 40-t indoor concrete spawning tanks at the AMSC. BATCH 1 BATCH 2 No. of females 6 14 Water temperature (C) Minimum 23.5 25.3 Maximum 26.5 27.5 Collected eggs (x106) Total 7.28 15.05 Fertilized 3.02 8.99 % fertilized 41.9 59.7 Collected larvae (x106) 0.84 2.76 Hatching rate (%) 27.9 30.7 (CONTINUED ON PAGE 40) The orange-spotted grouper Epinephelus coioides, locally known as hamour, is the food fish in greatest demand and correspondingly fetches the highest price in the local market. However, there has been a significant decline in natural stocks from severe over-exploitation in UAE waters over the last few years, as indicated by decreased landings. The high market demand and reduced natural supplies of the orange-spotted grouper make this species the top potential candidate for aquaculture in UAE.
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