Validated annual band-pair periodicity and growth parameters of blue-spotted maskray Neotrygon kuhlii from south-east Queensland, Australia
Abstract:Age and growth parameters were derived for blue-spotted maskray Neotrygon kuhlii from Moreton Bay in subtropical eastern Australia. Maximum age estimates of 13 and 10 years were obtained from female (n = 76) and male (n = 44) N. kuhlii, respectively. Estimated ages at maturity for 50% of females and males were 6·32 and 3·95 years, respectively. A three-parameter power function provided the best statistical fit to size at age data in both sexes, providing parameter estimates of y0 = 163·13, a = 58·52 and b = 0·58 for females and y0 = 165·13, a = 59·02 and b = 0·54 in males. The two-parameter von Bertalanffy growth function was used to estimate biological parameters based on disc width (WD) for both female (WD∞ = 465·81 mm, K = 0·13 year−1, b = 0·63) and male N. kuhlii (WD∞ = 385·19 mm, K = 0·20 year−1, b = 0·54). Annual band-pair deposition was observed in three calcein-injected N. kuhlii after periods of liberty ranging from 631 to 1081 days. Centrum edge analysis indicated that annual band-pair formation was generally consistent within this population, with translucent bands formed over spring and summer and opaque bands formed in autumn and winter. Individual growth rates obtained from tagged specimens were similar to power function growth predictions. These results support previous characterizations of this common trawl by-catch species as comparatively resilient to non-targeted catches, although higher catch rates outside Australia infer a need for cautious management.
Document Type: Regular Paper
Affiliations: School of Biomedical Sciences, The University of Queensland, St Lucia, QLD 4072, Australia
Publication date: 2009-12-01