The tentacled butterfly ray Gymnura tentaculata was described in 1841 from specimens believed to have been collected in the Red Sea. The historical range of this inshore, benthic species extended throughout the northern Indian Ocean from the Red Sea to the western Bay of Bengal. It is one of only two butterfly ray species known to occur in the north-west Indian Ocean. Despite intensive surveys throughout the region, it had not been seen in the coastal waters off India since 1973 and the last records were from Pakistan in 1986. In 2017 the species was assessed as Critically Endangered and flagged as Possibly Extinct on the IUCN Red List of Threatened Species.
However, during a monitoring programme in southern Iranian waters, the species was found to represent c. 15% of the ray bycatch in trawl fisheries. In 39 of 96 trawl hauls surveyed during October 2019–November 2020, a total of 367 individuals (disc width 14–85 cm) were recorded from the Gulf of Oman and eastern Persian Gulf. Based on this discovery and the absence of recent records from elsewhere (the species has not been recorded in recent elasmobranch-specific surveys in the Red Sea or Persian Gulf, or from Indian or Pakistani waters), this region appears to be the species’ last stronghold.
Fishing pressure is intense throughout the species’ former and current range, where severe ongoing declines in all ray populations have been reported. Surveys in Iranian waters combined with previous data suggest the tentacled butterfly ray population has declined by c. 86% over the past 30 years. The rediscovery of this Critically Endangered ray highlights the importance of monitoring landings.
We thank the Iranian Fisheries Science Research Institute, Prince Bernhard Nature Fund, and the Marine Conservation Action Fund of New England Aquarium for supporting this project, and a Future For Nature Award to MR-A.
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