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Overfished and under conserved: life-history, ecology and supply chain of the Endangered whitespotted whipray (Maculabatis gerrardi) and sharpnose whipray (Maculabatis macrura) from Southeast Asia

Naomi Clark-Shen , Andrew Chin , Chester Gan, Kathy Xu-Ting Ting, Celestine Terence, Darren Wee , Justin Ng Zheng Kai, Neil Hutchinson

Abstract

Context: The whitespotted whipray (Maculabatis gerrardi) and sharpnose whipray (Maculabatis macrura), are caught and traded in large volumes in Southeast Asia and listed as Endangered by the IUCN. Aims: This study aimed to provide insights to their biology, ecology, fisheries and markets. Methods: 95 specimens from the species complex (M. gerrardi = 45, M. macrura = 40, and undetermined = 10) caught from Indonesia and Malaysia, were examined, and an interview with a Singaporean seafood supplier was conducted. Key results: For M. gerrardi, the youngest mature male was 4 years old with 50% reaching maturity at 5.07 years, and the youngest mature female was 4 years old with 50% reaching maturity at 6.96 years. For M. macrura, the youngest mature male was 4 years old with 50% reaching maturity at 6.36 years, and the youngest mature female was six years old with 50% reaching maturity at 6.00 years, but with low sample size. The oldest specimen in the sample was 15 years old. Maculabatis spp. show asynchronous breeding with a littler size of one to five. There was no significant difference in the diets of both species, with Decapoda the dominant prey. The seafood supplier revealed that Maculabatis spp. are targeted by fisheries, and he perceives large declines in their population since he started in the business. Conclusions and implications: Considering the challenges distinguishing between the two cryptic species, life-history parameters that capture this species-complex as whole may be a more practical approach to management and are presented.

PC24086  Accepted 18 March 2025

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