Resumo Um experimento foi realizado durante 95 dias para avaliar as densidades planctônicas do policultivo do camarão branco Litopenaeus vannamei e da tilápia do Nilo Oreochromis niloticus. O delineamento experimental foi inteiramente casualizado com seis tratamentos e quatro repetições cada. Os tratamentos foram: monocultivo com 10 camarões m2 (10S:0T); policultivo com 10 camarões e 0,5 tilápia m2 (10S:0.5T); policultivo com 10 camarões e 1 tilapia m2 (10S:1T); monocultivo com 2 tilápias m2 (2T:0S); policultivo com 2 tilápias e 2,5 camarões m2 (2T:2,5S); e policultivo com 2 tilápias e 5 camarões m2 (2T:5S). Não foi realizada troca de água e nem fornecimento de aeração artificial durante o período experimental, apenas utilizou-se água para completar o volume perdido pela evaporação. O fitoplâncton variou de 78.981 a 303.260 cél.mL-1 e o zooplâncton variou de 470 a 1.421 org.L-1. Os grupos mais frequentes foram Bacillariophyta (fitoplâncton) e Rotífera (zooplâncton). Pode-se concluir que em sistema de policultivo do camarão branco (Litopenaeus vannamei) e a tilápia do Nilo (Oreochromis niloticus) não ocorrem modificações significativas nas densidades do fitoplâncton e zooplâncton em decorrência da alteração das densidades de estocagem do cultivo.

Abstract An experiment was conducted during 95 days to evaluate plankton densities in polyculture of Pacific white shrimp Litopenaeus vannamei and Nile tilapia Oreochromis niloticus. The experiment design was randomized with three treatments and four replicates each. The treatments were as follows: monoculture with 10 shrimps m2 (10S:0F); polyculture with 10 shrimps and 0.5 fish m2 (10S:0.5F); polyculture with 10 shrimps and 1 fish m2 (10S:1F); monoculture with 2 fishes m2 (2F:0S); polyculture with 2 fishes and 2.5 shrimps m2 (2F:2.5S); and polyculture with 2 fishes and 5 shrimps m2 (2F:5S). Neither water exchange nor aeration was provided during the experimental period, only water was used to complete the volume lost by evaporation. The phytoplankton ranged from 78,981 to 303,260 cells.mL-1 and the zooplankton ranged from 470 to 1,421 org.L-1. The most frequent groups were Bacillariophyta (phytoplankton) and Rotifera (zooplankton). In conclusion, in the polyculture system of Pacific white shrimp Litopenaeus vannamei and Nile tilapia Oreochromis niloticus there are no significant changes in the densities of phytoplankton and zooplankton due to the alteration in the culture stocking density.

O objetivo deste trabalho foi avaliar o desempenho de camarão marinho (Litopenaeus vannamei) e tilápia (Oreochromis niloticus) em policultivo, em tanques de cimento, submetido a diferentes densidades de estocagem e estratégias de alimentação, em comparação ao monocultivo. Dois experimentos foram conduzidos, ao mesmo tempo, em delineamento inteiramente casualizado, com três tratamentos e quatro repetições cada um. Os tratamentos do experimento I foram: monocultivo com 10 camarões por m² (10S:0T); policultivo com 10 camarões e 0,5 tilápia por m² (10S:0.5T); e policultivo com 10 camarões e 1 tilápia por m² (10S:1T). O camarão foi a principal cultura, e a alimentação fornecida foi baseada na biomassa de camarão. Os tratamentos do experimento II foram: monocultivo com 2 tilápias por m² (2T:0S); policultivo com 2 tilápias e 2,5 camarões por m² (2T:2.5S); e policultivo com 2 tilápias e 5 camarões por m² (2T:5S). A tilápia foi a principal cultura, e a alimentação fornecida foi baseada na necessidade dos peixes. No experimento I, a introdução da tilápia no cultivo de camarão resultou em baixo crescimento do camarão e baixa taxa de conversão alimentar. No experimento II, a introdução de camarão no cultivo de tilápia não interferiu no desempenho dos peixes. O policultivo é mais eficiente com a combinação de 2 tilápias e 2,5 ou 5 camarões por m² e alimentação baseada na necessidade dos peixes.

The objective of this work was to evaluate the performance of Pacific marine shrimp (Litopenaeus vannamei) and tilapia (Oreochromis niloticus), in a polyculture in tanks subjected to different stocking densities and feeding strategies, in comparison with monoculture. Two experiments were performed, at the same time, in a completely randomized design with three treatments and four replicates each. Treatments for experiment I were: monoculture with 10 shrimp per m² (10S:0T); polyculture with 10 shrimp and 0.5 tilapia per m² (10S:0.5T); and polyculture with 10 shrimp and 1 tilapia per m² (10S:1T). Shrimp was the main crop, and feed was provided based on shrimp biomass. Treatments for experiment II were: monoculture with 2 tilapia per m² (2T:0S); polyculture with 2 tilapia and 2.5 shrimp per m² (2T:2.5S); and polyculture with 2 tilapia and 5 shrimp per m² (2T:5S). Tilapia was the main crop, and feed was provided based on fish requirements. In the experiment I, tilapia introduction to shrimp culture resulted in lower shrimp growth and poor feed conversion rate. In experiment II, shrimp introduction to tilapia culture did not interfere with fish performance. Polyculture is more efficient with the combination of 2 tilapia and 2.5 or 5 shrimp per m² and feed based on fish requirements.

This study aimed to evaluate the productivity, growth performance and economic feasibility of polyculture of Nile tilapia Oreochromis niloticus and shrimp Litopenaeus vannamei at different stocking densities. Feed was provided based on fish requirements. The experiment was conducted at the Aquaculture facility of the Universidade Federal Rural do Semi-Árido - UFERSA, in a completely randomized design with five treatments and four replicates each. Treatments consisted of a tilapia monoculture with 2 tilapias.m-2; and polyculture with 2 tilapias.m-2 and L. vannamei at four different densities (3, 6, 9 and 12 shrimps.m-2). The initial individual biomass for fish and shrimp were 1.23±0.12 g and 0.133±0.009 g, respectively. Water quality parameters, temperature, dissolved oxygen, pH and transparency were monitored. The experiment lasted 120 days and biomass gain was evaluated every two weeks. Final biomass, survival and feed conversion rates were calculated at the end of the experiment. The economic analysis showed that polyculture systems at stocking densities of nine and twelve shrimps.m-2 resulted in higher gross revenue and operational profits of 120.9% and 97.5% respectively, with mean gross return significantly higher than the monoculture. The O. niloticus and L. vannamei polyculture in oligohaline water was shown to be technically and economically feasible. These two species can be cultured together, without competing for the same resources, because they have different trophic niche, thus increasing productivity and economic returns for the farmers.