Age and growth of Oreochromis aureus (Pisces: Cichlidae) in Sanalona Reservoir, Sinaloa, Mexico. Oreochromis aureus is an important fishing resource in this reservoir but little biological information is available for management purposes. To study its age and growth in the site, we obtained samples using gill nets of six mesh sizes, and collecting fish from commercial catches, on a bimonthly basis, from November 2006 to September 2007. Total length (L t), total weight (P t), sex and gonadosomatic maturity were analyzed. Age determination was done by readings of scale growth marks, and its validation was made by the marginal and gonadosomatic index. A total of 384 fish were collected. Length and weight varied from 125 to 345mm and from 40 to 671g, respectively. Growth in length and weight are described by the following von Bertalanffy equations: L t =416 [1-e-0.3682 (t+0.4975) ] and P t =1323[1-e-0.3682(t+0.4975)] ] 3.0652. Two growth marks per year were registered, these were associated to metabolic and environmental factors like reproduction and temperature.
Globally, the tilapia is the second most important group of commercial fish. Polyculture and growth were studied for 181 Nile tilapia, Oreochromis niloticus, in a seawater pond (30-37‰) at a density of 50 fish/m3 for six months (October to April) with 30 shrimp Litopenaeus vannamei at a density of 8 shrimp/m3 in two months (December-February) in an open tank of 3,6 m3. They were fed Camaronina”pellets” at libitum in the morning. The pond bottom was siphoned every other day, was maintained with constant aeration. Water exchange was 80% every two weeks. The temperature varied from 18 to 32oC. The tilapia grew from 72mm to 220mm, and 7g to 232g, survival was 92%. The total biomass was 38,6 kg. The shrimp grew from 6,8 g to 11,5 g and 102mm to 121mm. The survival rate was 100%. Total biomass was 219g. The feed conversion ratio (FCR) was 1,3:1,0 in both species. There was no problem between species; this polyculture is recommended.KEY WORDSPolyculture, growth, Litopenaeus vannamei, Oreochromis niloticus, biomass, density
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