58 June 2010 Growth and survival of Macrobrachium americanum Bate, 1868 juvenile prawns (Crustacea, Decapoda, Palaemonidae) stocked in tanks at different sizes Marcelo U. García-Guerrero1,2 and Javier Orduña Rojas1 There has been a global expansion of freshwater shrimp farming since 1995, but production mostly consisted of Macrobrachium rosenbergii (D’Abramo et al. 2003, New 2005). There are techniques for its production that may serve as guidelines to develop technology for cogeneric species, but biological differences may mean different requirements (Garcia Guerrero and Apun 2008). Thus, studies on new species with potential for aquaculture should be performed. Macrobrachium americanum from the western continental shelf of Middle America is an example. The demand for this edible shrimp cannot be supplied by fisheries. It is large with the maximum sizes according to Kensler et al. (1974) being 450g for males (Figure 1) and 225 g for females (Figure 2). Some effort to start its culture have begun, but a considerable amount of information is uncertain or unavailable. Prior to the determination of the demand, it will be necessary to establish whether it can actually be cultured profitably (Garcia Guerrero and Apun, 2008). First efforts must focus on the capture and acclimation of wild specimens to the culture environment. Many farms are unproductive simply because they are farming inadequate stocks (Jerry et al. 2005). Hence, customization of the animals to culture conditions is necessary. Because stocks of similar age may vary in size, the effect of stocking size was selected as a primary aspect to evaluate. The purpose of this article was to assess the growth and survival of M. americanum juveniles (Figure 3) stocked at different sizes in experimental tanks. Study Materials and Methods Juveniles were caught with a dragnet in the Sinaloa River (Figure 4) located in the state of Sinaloa, Mexico (25°57’N, 108°51’W). The river flows in a semitropical valley with an average water temperature of 24.1°C (min, 0.5; max, 44.5°C) and average rainfall is 938.5 mm/yr with total hardness of 83 mg/L CaCo3 (Muñoz and Escobedo 2005). Damaged juveniles, as well as those out of the proper size range (smaller than 0.06 g or larger than 0.30 g) or not positively identified as M. americanum (Hendrickx 1995), were discarded. In the laboratory, they were individuFig. 1. Adult male prawn of Macrobrachium americanum (Bate 1868) from Sinaloa River. Fig. 2. Adult female prawns of Macrobrachium americanum (Bate 1868) from Sinaloa River.
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