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Age, growth and spatial and interannual trends in age composition of jackass morwong, Nemadactylus macropterus, in Tasmania
journal contributionposted on 2023-05-16, 13:19 authored by Alan JordanAlan Jordan
Transverse sections of sagittae were examined. The first and second annual increments were defined by examination of the progression of otolith radius and length of the 0+ and 1+ cohorts. Growth in both sexes is rapid until âˆ¼5 years old (32-35 cm), and then slows appreciably. There was a broad range of lengths within individual age-classes, with a maximum of 12 age-classes present in a 1 cm length-class. Maximum ages of males and females were 41 and 30 years, respectively, which is considerably higher than previously estimated from whole otoliths. There was no significant difference in the growth curves between males and females, although this is influenced by the large number of juveniles and by the examination of relatively few large, older fish. The sex-specific von Bertalanffy growth parameters are: Lâˆž 38.4 cm FL, t0 -0.07 years, K 0.36 year-1 for females and Lâˆž 36.2 cm FL, t0 0.15 years, K 0.42 year-1 for males. The age composition was dominated by 4-7 year olds but showed evidence of considerable recruitment variability, particularly in the strong 1988 year-class. The relationship between the life-history strategy of N. macropterus and recruitment variability is discussed.
Publication titleMarine and Freshwater Research
Department/SchoolInstitute for Marine and Antarctic Studies
Place of publicationVictoria, Australia