Mukherji, Sushmita, Smart, Jonathan, D’Alberto, Brooke, Baje, Leontine, Chin, Andrew, White, William, and Simpfendorfer, Colin A. (2021) Preliminary age and growth estimates of the blue shark (Prionace glauca) from Papua New Guinea. Environmental Biology of Fishes, 104 (9). pp. 1163-1176.

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Abstract

Blue sharks (Prionaceglauca) are recognised as one of five key pelagic shark species in the Western Central Pacific Ocean (WCPO) due to their frequent incidental catch in tuna and billfish longline fisheries. Given their importance in the region, the aim of this study was to investigate the life history of this species for use in future population assessments in Papua New Guinea (PNG). Eighty-one vertebral samples were examined to provide preliminary age and growth estimates for P.glauca caught by commercial longline vessels operating in the Bismarck and Solomon seas. Ages ranged from 10 to 25 years. A Bayesian approach using Markov Chain Monte Carlo (MCMC) was used to estimate growth parameters. The von Bertalanffy model provided the best fitting growth model (males: L∞ = 379 cm, L0 = 45.8 cm, k = 0.07 year−1; females: L∞ = 329.2 cm, L0 = 45.8 cm and k = 0.08 year−1; combined sexes: L∞ = 350.8 cm, L0 = 45.8 cm, k = 0.07 year−1). The asymptotic length parameter estimate for the male P.glauca population from PNG was the largest reported. Our results demonstrate that intraspecific variation in life history traits of P.glauca across its entire distribution is likely due to differences in methodology, sample size and interpretation of growth bands rather than regional differences in growth. This study takes an important step towards facilitating management strategies for P.glauca in PNG by producing preliminary growth estimates for the species. However, further studies with larger sample sizes are required to conduct age validation and refine the life history information for this highly migratory species in PNG.

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