ABSTRACT
The aim of this study was to analyze the financial and economic risks of tilapia cage culture across different production water volumes (m³). The production water volumes evaluated were 10 to 50 thousand m³ (Small Volume, SV), 51 to 150 thousand m³ (Medium Volume, MV), 151 to 300 thousand m³ (Large Volume, LV), and >301 thousand m³ (Extra-Large Volume, ELV). Productivity and economic data were obtained from a commercial Nile tilapia cage farm with 232 net cages installed in a neotropical reservoir, in Brazil, from 2017 to 2019. Cost and profitability analyses, economic feasibility, and risk and sensitivity analyses were performed using a Monte Carlo simulation. The implementation of commercial tilapia cage farming relies mainly on feed prices. The initial investment demand is proportional to the size of the farms. On the other hand, MV, LV, and ELV tilapia farms showed the lowest financial risks despite the higher investments. These farms presented a medium-low risk at ≈39% probability, whereas the SV farm presented a medium to medium-high risk at 51.17% probability. Thus, fish farms with a production volume above 51 thousand m³ tend to be more profitable and have a ≈36% probability of low financial and economic risk with a Payback period of fewer than 10 years, mainly due to the lower feed costs per mass of fish produced. This study assists investors in choosing a better path toward a more viable and profitable activity.
ABSTRACT
ABSTRACT: The present research aimed to investigate the stabil¬¬ity of pellets and phosphorus leaching of diets formulated for juveniles of Nile tilapia (Oreochromis niloticus), with different sources of phosphorus and different exposure times in water. Six diets were elaborated by varying the source of phosphorus (1 ‒ dicalcium phosphate (DP); 2 ‒ meat and bone meal (MBM); 3 ‒ poultry meal (PM); 4 ‒ anchovy meal (AM); 5 ‒ tilapia filleting industrial meal (TM); 6 ‒ calcined bone meal (CBM)) and, then, were submitted to four exposure times in water (5, 10, 15 and 20 minutes), with three replicates. Thus, 72 aquariums of 30‒liters were used, each being an experimental unit. All diets were evaluated for electrical conductivity of water, turgidity of pellets, mineral matter leaching, flotation of pellets, and total phosphorus leaching. Only turgidity and flotation of pellets varied with the different sources of phosphorus in the diets. The MBM diet had the highest turgidity of pellets. The PM, AM, and CBM diets had the highest flotation of pellets. The total phosphorus leaching had a linear effect with the increase of the exposure time, showing a greater release of phosphorus in the water with increase of exposure time. Data showed that PM, AM, and CBM diets had less potential impact on the aquatic environment. Conversely, the TM diet has greater polluting potential. These results showed that diets formulated with different sources of phosphorus exhibit distinct actions in the water, providing different effects on the fish culture environment.
RESUMO: O presente trabalho tem como objetivo investigar a estabilidade de pellets e a lixiviação do fósforo na água proveniente de diferentes dietas formuladas para juvenis de tilápia do Nilo (Oreochromis niloticus), considerando distintas fontes de fósforo e diferentes tempos de exposição na água. Para tanto, foram elaboradas seis dietas com variação da fonte de fósforo (1: fosfato dicálcico (DP); 2: farelo de carne e ossos (MBM); 3: farelo de aves (PM); 4: farelo de anchova (AM); 5: farelo industrial de filetagem de tilápia (TM); 6: farelo de osso calcinado (CBM)), as quais foram submetidas a quatro tempos de exposição em água (5, 10, 15 e 20 minutos), com três repetições. Utilizaram-se 72 aquários de 30 litros, sendo cada um deles uma unidade experimental. A água dentro dos aquários foi mantida sob constante aeração e temperatura ao redor de 25 °C. Todas as dietas foram avaliadas quanto à condutividade elétrica da água, turgidez, lixiviação de matéria mineral, flotação de pellets e lixiviação total do fósforo. Apenas a turgidez e a flutuação dos pellets variaram com as diferentes fontes de fósforo nas dietas. A dieta MBM apresentou a maior turgidez de pellets. As dietas PM, AM e CBM apresentaram a maior flutuação de pellets. A lixiviação do fósforo total teve um efeito linear com o aumento do tempo de exposição, resultando em maior liberação de fósforo na água. A lixiviação de matéria mineral apresentou interação entre fontes de fósforo e tempos de exposição das dietas, com efeito linear para a dieta TM. As dietas PM, AM e CBM apresentam as menores concentrações de efluentes em relação a dieta TM. Esses resultados revelaram que dietas formuladas com diferentes fontes de fósforo apresentam ações distintas na água em relação ao potencial poluidor.
