AGE AND GROWTH OF JACK MACKEREL TRACHURUS SYMMETRICUS MURPHYI (NICHOLS, 1920) FROM CENTRAL CHILEAN WATERS

Abstract

Age determinations íbr jack mackerel (Trachurus symmetricus murphyi Nichols, 1920) using otoliths were made for fish collecled in 1983 and 1984 from the Talcahuano fishery area, Chile. No significant differences were deiected in length increase between males and females as function of otolith size (P = 0,05). An isomeiric relaiionship between mean fork length and total weight was estimated for ages I to XI, which were considered for fitting the parameters of the Von Bertalanffy growth model modified by Beverton & Holt, the best age - fork length fitting was: k = 0,0741; Lx = 65,2286 cm and to = -2,4 102. For age - total weight relationship it was k = 0,0735: Wx = 2776,6510 g; to = 2,4199 and b = 2,9563. VVhen comparing the age - length relationship obtained, the majority of previous studies in Trachurus sp. show similar results. Finally, hypotheses and changes related to age structure of jack mackerel are discussed.