Preliminary Study of Age and Growth of Bluefin Tuna Thunnus thynnus (Scombridae) from Fish Farm in the East of Tunisia

The Atlantic bluefin tuna, Thunnus thynnus, is a fish of high economic interest. Nevertheless, its biology is not yet well understood. The objective of the study is to describe the age and the growth of the bluefin tuna collected from the tuna farm located in the East area of Tunisia (Salakta-Mahdia). The age is estimated by counting the annuli on the cross sectioned dorsal fin ray and the Von Bertalanffy growth equation is established: Lt = 390×(1 – exp(−0.07x(t + 1.23)). The estimated age ranges from 3 to 14 years. Most of the catch is composed of bluefin tuna of age class 4 to 7. A positive allometric growth is established for fattened bluefin tuna. The condition factor ranges from 0.98 to 2.63 with a mean value of 1.79 ± 0.26. The mean condition factor shows an increasing trend with age.