Management strategies for seabream Sparus aurata cultivation in floating cages in the Mediterranean Sea and Atlantic Ocean

For decades, research and development efforts have focused on fish cultivation in floating cages. Despite this focus, and the considerable private and public sector resources invested in these systems, there is a scarcity of economic data derived from the great number of variables present in these systems. A reliable way of generating economic studies is through systems modeling that relates biological, environmental, technical, and economic variables. This study presents results from a computer simulation of seabream production in floating cages under two scenarios: one representing conditions in the Mediterranean Sea, and the other in the Atlantic Ocean. A company operating in the Atlantic (Canary Islands, Spain) provided the majority of data, though some of them were provided by the University of Las Palmas, also in the Canary Islands. Given the assumptions in the simulation case study, the production cost for 1 kg of seabream in floating cages in the described systems is US$2.64 in the Mediterranean and US$2.90 in the Atlantic, and the internal rates of return were 27% and 59%, respectively. The results of model sensitivity analysis for both scenarios show that this cultivation system is more sensitive in the Mediterranean than in the Atlantic. This means that changes in system variables convey lower effects on the production and economic results in the Atlantic scenario than in the Mediterranean. In both scenarios, the feed ration size was one of the variables that improved feed conversion rates. It also improved costs and profitability in greater proportions than the other variables. The reduction of the feed ration below the levels recommended in feed tables lowered the feed conversion rate but increased the number of days in the seabream cultivation cycle, leading to higher production costs and lower internal rates of return. The analysis also showed that greater benefits and profitability could be obtained by raising production capacity through increases in the final stocking density of the system.