Le thon rouge Thunnus thynnus thnnus L.1758 des eaux tunisiennes : Etats des lieux, peche et activites d'engraissement
Keywords:
Purse seines, Temperature effects, Adaptations, Acclimatization, Floating barriers, Environmental impact, Leases, Water temperature, Cages, Marine fish, Commercial fishing, Growth, Aquaculture enterprises, Cage culture, Fish culture, Mortality causes, Thunnus, Thunnus thynnus, Marine, MED, Cyprus, Cyprus, Italy, INW, Japan, Spain, Tunisia, Malta, CroatiaAbstract
The fattening of the bluefin tuna knew a renewal of interest since the Japanese economic boom i.e. toward the middle of the year 70. To this time projections put in evidence that the world production would not be sufficient to satisfy the Japanese market anymore. It is this report that brought big Japanese firms to think on the fattening of bluefin tuna. This technology was exported in Spain where the activity started effectively in the beginning of years 1990 to reach its apogee toward years 1996-1997. Several Mediterranean countries followed the step of Spain such as Croatia, Malta, Cyprus, Italy, etc. In Tunisia during the last six years (2003-2008) bluefin tuna (BFT) farming reached around 2500 tons per year of harvested fish. The industry consists of 4 commercial companies using 2 lease sites (Hergla (Sousse) and Chebba-Salakta (Mahdia). It was based on fishing BFT by purse seine and growing them in about 28 cages of 50 m diameter for a few months. The BFT are fed daily small pelagic fish by hand, Farm mortality is about 3% to 5% per year, while stress-related mortality during the adaptation period is around 10%. Daily feed consumption was between 5% and 10% of biomass, within the temperature range from 18°C to 24°C. The improvement of the environmental performances in BFT farming is of the highest importance for this industry in Tunisia.
