Culture of white shrimp (Litopenaeus vannamei Boone, 1931) with zero water exchange and no food addition: an eco-friendly approach

Juveniles (3.5 +/- 0.3 g) of the white shrimp Litopenaeus vannamei were grown during 40 days with no water exchanges, no food addition and four initial densities (25, 50, 75 and 100 g m(-3), corresponding to between 8 and 32 shrimp m(-2)), to determine growth rates, which could be achieved using the periphyton growing on artificial substrates as the only food source. The experimental culture units were 12 polyethylene 1 m(3) cylindrical tanks with 4.8 m(2) of total submerged surface (bottom and walls), provided with 7.2 m(2) of artificial substrate (Aquamats (TM)). There were no significant differences in the ammonia and nitrite concentrations determined in the four treatments (0.17-0.19 and 0.10-0.11 mg L-1, respectively), which remained below the respective levels of concern for shrimp cultures. Mean survival was similar, and ranged from close to 91 to 97%, whereas there were significant differences in mean individual weight, which ranged from 11.9-10.6 g shrimp(-1) for the two low initial densities (25 y 50 g m(-3)), to 8.3-7.7 g shrimp(-1) for the other treatments. However, because of the high survival and of the higher initial density, the best biomass yield was with 100 g m(-3). The final nitrogen contents of sediment and water were lower than the initial values, and between 36 and 60% of the difference was converted into shrimp biomass.