| The temporal evolution of the demographic structure of bluefin tuna (Thunnus thynnus, Linnaeus 1758) and of the little tuna (Euthynnus alletteratus, Rafinesque 1810) by the Tunisian traps of Sidi Daoud and Monastir is studied during 3 periods (1979-1983; 1988-1992 and 1993-1997). This survey showed the two points of passive capture landing draw the bluefin tuna from two populations of different composition. The fish taken from Tunisian waters do not from a homogenous group of similar beings, since they result from a mixture of local Mediterrean and Atlantic forms. This conclusion was arrived at by Heldt (1929), and confirmed in 2004, by displacement studies indicated that, after reproduction, the adults (<100kg) remained in the Mediterranean, and that,... |
