Interpretation of the Scales of the Yellow-Eye Mullet, Aldrichetta forsteri (Cuvier & Valenciennes) (Mugilidae)

Abstract

The yellow-eye mullet scale is of the typical percomorph type, feebly ctenoid in most cases, but cycloid in the mid-flank region, which provides the best scale for age and growth determinations. The annual "break" is more obvious in the posterior sector than in the anterior. Above a length of 5 cm (length to caudal fork) there is a straight-line relationship between increments in dimensions of scale and increments in length of the fish. The scales of Victorian and Tasmanian fish are smaller than those of Western Australian fish, which is in accord with the rather larger number of scales in eastern fish. The annual "breaks" become apparent in spring when growth recommences after the winter cessation. As western fish are winter spawners and eastern fish summer spawners, the age and size attained at the time of formation of tho annuli differs in the two stocks. Females grow faster than males. Lengths (cm) attained each winter average as follows:

Year I II III IV V VI VII

Western fish 11 18-19 24-25 29-32 32-35 38 39

Eastern fish 5 12-13 19-21 24-27 30

The Petersen method of modal progression gives rather higher readings in the first and second years, probably as a result of mesh selection.