| Popis: |
Age and growth of the sardine Sardina pilchardus, caught in the northern and southern areas along the Tunisian coast, were determined by otolithometry. In the two areas, sardines showed a positive allometry. However, at the same length, sardines of the off-shore area (north area) were heavier than those of the coastal water (south area), showing that trophic off-shore regions are more suitable for this species. In both areas, the sardines have short life-spans and grow fast. No growth difference was recorded between males and females in the same area. However a different growth pattern was found between the sardines from the north that have on average a statistically greater size at the same age than those from the south area. The corresponding von Bertalanffy growth equations were in the north area: LF = 20.1[1 - exp (-0.28 (t+2.04))] and in the south area: LF = 17.8[1 - exp (-0.26 (t+2.46))]. Abiotic and/or genetic factors could be involved to explain the growth differences observed between the two areas. |
