White shrimp Penaeus vannamei culture in freshwater at three densities: Condition state based on length and weight

The commercial culture of shrimp in low water salinities has been successfully achieved. However, there are no long-term studies on the growth response of shrimp culture in freshwater. In the present study white shrimp Penaeus vannamei was cultured in freshwater (0 ppt) at three densities (90,130 and 180 shrimp m(-2)) and comparisons made of the resulting growth, length-weight relationship and condition factor data. Gravimetric data were recorded during a 210-day trial to estimate growth rates, the length-weight relationship and the condition factor (according to Fulton's equation). Weight gain results showed the freshwater culture system to be viable, with effects from density (P<0.05). Growth rates decreased as density increased, exhibiting an inverse relationship (P<0.05, R-2=0.68). Survival decreased as density increased with differences between treatments (P<0.05). A potential model was used to analyze the length-weight relationship of the treatments. The slopes were different between treatments according to an ANCOVA and a Tukey test (P<0.05). The function exponents showed that the 130 shrimp m(-2) treatment produced organisms with isometric growth (b=2.99) in good condition (t=0.96; P>0.05). The 90 shrimp m(-2) treatment produced positive allometric growth and the 180 shrimp m(-2) treatment negative allometric growth. (C) 2008 Elsevier B.V. All rights reserved.