Age structure of the population of weakfish cynoscion guatucupa (cuvier) in the bahia blanca waters, agrentina

摘要

The age of Cynoscion guatucupa from the Bahia Blanca estuary (39deg LS, south-western Atlantic waters, was studied by means fop sagittal otoliths. In total 1018 fish, cuaght by the fishing fleets operating in the Bahia Blanca area, were collected between April 1991 and May 1993. The annual periodicity in the growth marks was validated by examining the monthly proportions of opaque and hyaline growth bands in the margin of the sliced (edge) otoliths. Annulus formation occurred in June-August. The age for juveniles, ranging from 5 to 15 cm TL, was 0.For adults, the ages raged from 5 to 23 years (40-52 cm TL) for females and 7 to 22 years (40-51 cm TL) for males. Length-weight relationships were W (g) =0.0067 L(cm) exp. 3.18 for juveniles, W(g)=0.299 L(cm) exp. 2.06 for adult females and W(g)=0.269 L(cm) exp. 2.08 for adult males. At the same age, females were longer and heavier than males. Like other sciaenids, C.guatucupa is a typical inhabitant of estuaries and coastal regions. In the study area, the juveniles remain in the estuary during their first year of life and adults enter after the spawning period, for feeding and recovery.