Avaliação da produção de camarões juvenis da espécie Penaeus vannamei em sistema de raceway para fins experimentais no Laboratório de Nutrição de Organismos Aquáticos do Labomar/UFC

Abstract

The nursery phase aims to provide better adaptation of post-larvae (PLs) to the farm's water quality conditions, in addition to enabling the stocking of larger and more resilient shrimp for the start of grow-out. This study aimed to evaluate the stages of the production process for obtaining juvenile shrimp of up to 1 g of the species Penaeus vannamei. The study was conducted in 10 enclosures of 9 m³ with rectangular mesh (1.5 x 2.5 mm ø) positioned in two rows of five units in a 260 m³ raceway lined with geomembrane. The enclosures were flexible and anchored to the bottom with weights. The raceway system had an external 5 m³ settling tank and a 10 m³ reservoir for continuous water recirculation, and it was fully covered with a 70% shade screen. The enclosures were stocked with PL16 post-larvae, with an initial body weight of 18 ± 2 mg, tested negative for IMN and WSS viruses (quantitative qPCR/TaqMan reagents). The animals were stocked at 5,698 ± 87 PLs (0.73 ± 0.01 PL/L) per enclosure and fed exclusively on trays six times a day (at 07:00, 09:00, 11:00, 13:00, 14:00, and 15:30) with an experimental diet containing 40% crude protein, composed of 35% krill meal, with four particle sizes (up to 250 μm; 300-425 μm; 600-850 μm, and 1,000 μm). After 11 days of culture, 1,032 Nile tilapia fry weighing 1.67 ± 6 g were stocked in the raceway system to reduce clogging of the enclosure screens. The culture water had an average (± standard deviation) of 13.3 ± 0.4 g/L salinity, 7.9 ± 0.3 pH, surface temperatures of 27.2 ± 0.5°C and 27.4 ± 0.5°C, bottom temperatures of 26.0 ± 0.18°C and 26.5 ± 0.16°C, and dissolved oxygen levels of 6.15 ± 0.6 mg/L and 8.00 ± 0.6 mg/L, in the morning and afternoon, respectively. After 21 days of cultivation, the shrimp were harvested, biomass determined, and 150 shrimp from each enclosure were individually weighed. A total of 42.41 kg of shrimp was obtained, with an average final survival rate of 75.2 ± 15%. Of the 10 enclosures, two had a final survival rate below 60%, while the others ranged from 66.0 to 93.9%. The final body weight of the shrimp ranged from 0.73 to 1.20 g, with an average of 0.99 ± 0.15 g. The feed conversion ratio was 1.13 ± 0.14, with a minimum of 0.94 and a maximum of 1.34. It was concluded that the enclosure system installed in the raceway provides adequate zootechnical indices while maintaining high water quality levels without the need for water exchange. The inclusion of Nile tilapia was essential in helping reduce the organic load present in the system.