Preliminary life history of the Critically Endangered bottlenose wedgefish Rhynchobatus australiae from Southeast Asia

• Published in: Endangered species research Vol. 53; pp. 363 - 378
• Main Authors: D’Alberto, BM, Clark-Shen, N, Xu Tingting, K, Green, ME, Hutchinson, N, Chin, A, Simpfendorfer, CA
• Format: Journal Article
• Language: English
• Published: Inter-Research 14.03.2024
• ISSN: 1863-5407; 1613-4796
• DOI: 10.3354/esr01294

The bottlenose wedgefish Rhynchobatus australiae has experienced substantial population declines throughout its range. However, there is a lack of life history information (age, growth, and maturity) available for this species to inform conservation and management efforts. A total of 48 R. australiae samples were purchased from 2 fishing ports in Singapore between July 2018-July 2019. Species identification was confirmed by mtDNA barcoding using the NADH2 region. Length of specimens ranged from 506-1645 mm total length (TL), and ages ranged from 0-11 yr. Multi-model analysis was used to estimate growth parameters using a Bayesian approach with informative priors. The von Bertalanffy model was the best fitting growth model for the combined sexes ( L ∞ = 2814 mm TL; L 0 = 517 mm TL; k = 0.07 yr -1 ), for females only ( L ∞ = 3053 mm TL; L 0 = 504 mm TL; k = 0.06 yr -1 ), and for males only ( L ∞ = 2741 mm TL; L 0 = 497 mm TL; k = 0.07 yr -1 ). Preliminary results indicate that females and males may mature at different ages and lengths, with females ( A 50 = 3.25 yr; L 50 = 1014 mm TL) matured younger and at smaller sizes, than males ( A 50 = 5.03 yr; L 50 = 1197 mm TL). R. australiae has an estimated theoretical longevity of 40 and 47 yr for males and females, respectively. This study provides the first preliminary species-specific life history information for R. australiae , suggesting that this species in Southeast Asian waters is slow-growing. This information will further the biological knowledge available for this species and can be used to help design effective management and conservation measures.