The life (history), diet and death of the blackspot shark (Carcharhinus sealei) from South-east Asia

N. Clark-Shen; A. Chin; J. Domingos; N. Hutchinson

doi:10.1071/MF24099

RESEARCH ARTICLE (Open Access)

Next Contents Vol 75(16)

The life (history), diet and death of the blackspot shark (Carcharhinus sealei) from South-east Asia

N. Clark-Shen

^A ^* , A. Chin ^B , J. Domingos ^A and N. Hutchinson

^A

+ Author Affiliations

- Author Affiliations

^A School of Science and Technology, Tropical Future Institute, James Cook University, Singapore 387380, Singapore.

^B Centre for Sustainable Tropical Fisheries and Aquaculture, James Cook University, Townsville, Qld 4811, Australia.

^* Correspondence to: naomi.clarkshen@my.jcu.edu.au

Handling Editor: Colin Simpfendorfer

Marine and Freshwater Research 75, MF24099 https://doi.org/10.1071/MF24099

Submitted: 25 March 2024 Accepted: 4 October 2024 Published: 21 October 2024

© 2024 The Author(s) (or their employer(s)). Published by CSIRO Publishing. This is an open access article distributed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License (CC BY-NC-ND)

Abstract

Context

The blackspot shark (Carcharhinus sealei) is a small-bodied coastal shark often incidentally caught in fisheries across South-east Asia.

Aims

This study aimed to document the species’ biology, ecology, fisheries and markets to inform conservation.

Methods

In total, 103 blackspot sharks from Indonesia (n = 101) and Singapore (n = 2) were examined to determine biological parameters (growth rate, age at maturity, reproductive traits and diet). An interview with a Singaporean seafood supplier gave insight to population trends, fisheries and markets.

Key results

Males attained a maximum age of 9 years, the smallest mature individual measured 709-mm stretched total length (STL), with 50% reaching maturity at 6.15 years. Females attained a maximum age of 11 years, the smallest mature individual measured 730 mm STL, with 50% reaching maturity at 6.12 years. The species has an overall growth rate (k) of 0.37 year⁻¹. Reproduction was asynchronous, with only two pups produced per litter. Crustaceans dominated the diet of juveniles, whereas bony fishes and cephalopods dominated the diets of adult males and adult females respectively.

Conclusions

Blackspot sharks have a moderately fast growth rate, but a late age-at-maturity and a low fecundity. Diet differed between the sexes as well as adults and juveniles.

Implications

The low fecundity and late maturity of blackspot sharks increase their vulnerability to exploitation. Blackspot sharks are now listed on CITES-Appendix II, but mortality may remain high because they are reportedly often caught incidentally.

Keywords: age and growth, bycatch, conservation, ecology, elasmobranch, fishery, Indonesia, life history, reproductive biology.

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