Improving estimates of growth for pearl perch (Glaucosoma scapulare) in Queensland, Australia

Abstract

The pearl perch (Glaucosoma scapulare) is endemic to the east coast of Australia in depths to 150 m. The species has a long history of exploitation, and the stock is currently depleted. Previous research indicated the species is long lived and slow growing based on fishery-dependent sampling undertaken in the late 1990s and early 2000s on traditional fishing grounds at the southern end of the species’ range. Increasing fishing power has facilitated the expansion of the fishery to areas to the north and east of traditional grounds, which has resulted in the appearance of older fish (>10 yr) in fishery-dependent samples not previously observed. The current study estimated the growth parameters using 1153 length-at-age observations from fish collected in Queensland between January 2020 and December 2021. The lack of significant numbers of individuals at either end of the age frequency distribution necessitated the estimation of growth in a Bayesian framework with informative priors for length-at-age-zero and maximum length using a multi-model approach. The von Bertalanffy growth function (VBGF) was found to best fit the observed length-at-age data and the estimated VBGF parameters were L∞ = 562 mm FL, L0 = 2.02 mm FL and k = 0.295 yr−1. The high proportion of older fish in samples, combined with prior information on relevant parameters, improves growth parameter estimation by reducing bias and facilitating improved model fits to observed length-at-age data.