Age and growth of greenback flounder (Rhombosolea tapirina) from southern New Zealand.

Includes bibliographical references (p. 9)

Two hundred and seventy-five greenback flounder were sampled from southern New Zealand waters. Biological data, including fish length, weight, sex, and gonad maturity were collected from all specimens. Regression equations for defining length-weight relationships were calculated and presented for male and female fish separately and for both sexes combined. Counts of growth zones in unprepared whole otoliths and prepared thin-sectioned otoliths were used to determine ages, von Bertalanffy growth parameters, and natural mortality. Growth is rapid throughout the lifespan of greenback flounder. Females reached a slightly greater maximum length than males, but the difference was not significant at the 95% level of confidence. Differences in growth rate were also not significant at this level. Over 90% of sampled fish were 2 or 3 years of age, with maximum ages of 5 and 10 years being obtained for male and female fish respectively. Ageing error was considered to be minimal, as both within-reader and between-reader ageing variability showed no significant systematic difference or bias. Natural mortality was 0.85 for males and 0.42 for females. It is suggested that 0.85 is the most appropriate estimate at this stage as only 1% of all fish exceeded 5 years. Greenback flounder growth parameters and identification difficulties are discussed, and it is concluded that the species should continue to be managed as a single (FLA) complex under the Quota Management System (QMS).