Age and growth in length of Micromesistius australis, Norman, 1937 (Pisces, Gadidae), in the southern zone of the Argentine Sea

It was carried out the otolith reading of more than 1100 specimens of Micromesistius australis, caught in waters of the southern Argentine Sea during the cruises made by the ships Walther Herwig and Shinkai Marú in agreement with the Argentine Republic, in the years 1978 and 1978/79 respectively. For the interpretation of the growth rings, the otoliths were previously subjected to the paraffin inclusion and cutting technique. A distribution of length frequencies for each sex was made. A nearly linear relation between the otolith length and the fish total length was obtained, for which the times when back calculations were made, the direct proportion formula was applied. When it was verified that there were growth differences between both sexes by the analysis "t" of Student, two curves were made up; one for males and the other for females. A linear regression was made and the equation of Von Bertalanffy was estimated as:
Lt= 58.18 [1-e-0.1709 (t+2.44)]
Lt= 63 [1-e-0.1134 (t+5.2)] giving Lt in cm and t in years.
For the estimation of the general equation parameters the first 15 age classes in males and the first 21 in females were taken into account. The theoretical Lt values corresponding to the females were higher than those of the males in all the age classes.