World Aquaculture 23 At the beginning and end of the experiment, fish anesthetized with benzocaine, 1g/20L-1 water were individually measured using an ictiometer and weighed using a digital electronic scale (precise to 0.01 g). The fish were fed once daily until satiation with chopped bycatch obtained from local fishermen. Food consumption was measured by weighing the food provided daily. The study lasted 30 days. Results and Discussion The limited literature on this species cites its distribution from the tropical western Atlantic to southeastern Brazil (Allen 1985, Moura and Lindeman 2007, Araujo et al. 2008 and Claro and Lindeman 2008). The occurrence of L. cyanopterus on the coast of Santa Catarina, southern Brazil, observed in this study, shows that this species has a wider geographical distribution than has been previously published. The absence of mortality in the present study agrees with the data obtained by several authors in relation to other species of snapper (Rios Filho 2001, Botero and Ospina 2003), showing the rusticity and adaptability of the species for mariculture. The use of bycatch fish for feeding led to good growth results for the cubera snapper, which reached an average weight gain of 107.4 grams in just 30 days (Table 1), supporting the assertion of González-Sansón and Aguilar Betancourt (1986), that fish are the main food source of L. cyanopterus. The feasibility of using bycatch fish for feeding marine fish culture in Brazil has already been demonstrated by Sanches et al. (2007) with real-grouper Epinephelus marginatus (Lowe 1834), that study highlighting the low cost of this diet in relation to other commercial operations. The results relating to final weight, daily weight gain and survival rate of L. cyanopterus were higher than those obtained for mutton snapper Lutjanus analis (Cuvier 1828) by Watanabe (2001) and Benetti et al. (2002). Watanabe (2001) obtained 140.8 g of fish in 168 days, with weight gain of 0.78 g day-1 and a survival rate of 97.8 percent when fed with a 50 percent crude protein diet, and this low weight gain Cubera snapper cultured in net cages in Brazil. Table 1. Means and standard deviations of the productive performance of cubera snapper L. cyanopterus kept in net cages during the experimental period of 30 days. Variable Results Initial length (cm) 32.6 ± 5.8 Initial weight (g) 456.3 ± 289.1 Initial biomass (g) 3194 Survival (%) 100 Final length (cm) 32.9 ± 5.7 Final weight (g) 563.7 ± 332.1 Final biomass (g) 3946 Weight gain 107.4 ± 36.8 DWG (g day-1)* 3.8 ± 0.6 SGR (%LW day-1)** 1.5 ± 0.3 FCR*** 2.8 ± 0.5 *DWG = daily weight gain; **SGR = specific growth rate; ***FCR = food conversion rate was justified by the author as a result of low temperatures (from 18 to 25° C). Benetti et al. (2002), studying the performance of mutton snapper L. analis in cages, showed that the fish grew from 16.5 g to 330.7 g in 246 days using a commercial diet with 50-53 percent crude protein and 13-14 percent crude fat. The daily weight gain was 1.28 g day-1, and the survival rate of 70 percent. The results presented here are also more impressive than those reported by Botero and Ospina (2003), who evaluated a culture of L. analis that was fed with a 45 percent crude protein diet and that obtained a weight gain of 372.9 g in 118 days (average daily gain of 3.16 g) with a survival of 97.6 percent. In comparison with the growth of other snapper species fed with alternative food sources, the productive performance of L. cyanopterus showed superior results, demonstrating its suitability for intensive culture. Cabrera et al. (1997), using bycatch as a food source for gray snapper Lutjanus griseus (Linnaeus, 1758), achieved a daily weight gain of 1.63 grams, with the fish reaching 425.0 g in 8 months and having a survival rate of 88 percent. In other research, Castillo-Vargasmachuca et al. (2007) studied the performance of spotted rose snapper Lutjanus guttatus (Steindachner 1869) in net cages fed diets containing 35 percent crude protein and 7 percent crude fat; the fish grew from 110.2 g to 366.1 g in 153 days, with a weight gain of 1.82 g day-1 and survival rate of 71.5 percent. To date, there are no studies on the growth of L. cyanopterus under culture conditions. Cervigón (1993) reported that this species had a fast growth rate, based on specimens kept in public aquariums. This study provides pioneer research data on the species. The specific growth rate (SGR) of L. cyanopterus in this study, is similar to those obtained by Watanabe (2001), also 1.5, but higher than those obtained by Benetti et al. (2002) and Botero and Ospina (2003), who reported rates of 1.0 and 1.1, respectively.
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