Kolkata: Scientists from the Zoological Survey of India (ZSI), in collaboration with the ICAR-Central Marine Fisheries Research Institute (CMFRI) and international experts, have discovered a new species of deep-sea skate in the southeastern Arabian Sea.Named Dipturus dhritiae or the Arabian Skate, the species was collected from depths of 400-600 metres off Kerala and the Wadge Bank region during investigations under the ministry of earth sciences’ flagship Deep Ocean Mission.The discovery is significant as the skate had remained unidentified for more than four decades. Specimens caught incidentally in commercial deep-sea shrimp trawls had earlier been misidentified as Dipturus springeri. Detailed morphological studies and genetic analysis have now established it as a distinct species.D dhritiae can grow to at least 131.5cm and is distinguished by, among other features, five distinct rows of thorns along its tail. Complete mitochondrial genome sequencing showed a genetic divergence of 3.8%-4.7% from its closest known relative, the Travancore Skate, confirming its distinct identity.The species has been named after ZSI director Dhriti Banerjee, the organisation’s first woman director, in recognition of her contribution to research on India’s biological diversity.“Deep sea remains largely unexplored, and every survey provides a crucial opportunity to expand our understanding of marine biodiversity,” said Banerjee, who is also the lead principal investigator of the Deep Ocean Programme.She said deep-sea sharks and rays were particularly vulnerable to fishing pressure because of their low reproductive rates and slow population recovery.“Deep-sea sharks and rays possess biological characteristics that make them exceptionally vulnerable to overexploitation—including low reproductive output, slow population recovery and high susceptibility to incidental capture in commercial fisheries. Identifying these species before their populations decline is essential for developing effective, targeted conservation strategies,” Banerjee said.The research team, comprising K K Bineesh and Anil Kasinath of ZSI, Akhilesh K V of CMFRI and David A Ebert of the US, has also mapped the Kollam Slope Important Shark and Ray Area (ISRA) within India’s Exclusive Economic Zone.
