A poorly known deep sea skate under pressure: first biological observations of the data-deficient travancore skate (Dipturus johannisdavisi)

Context Dipturus johannisdavisi is a little known deep-sea skate from the Indian Ocean, with limited biological information and a Data Deficient IUCN listing. Aim This study provides baseline information on size structure, life-history traits, diet, and fishery interactions to support future conservation assessment. Methods Specimens (N = 61) were collected from shrimp-trawl bycatch off south-western India (200–600-m depth). These were examined to describe exploited length classes and life-history characteristics. Key results Individuals ranged from 23.5 to 74.7 cm TL, the latter representing the maximum confirmed size for the species. Females were more abundant than males (2.39:1) and attained larger sizes. Growth was near isometric (b = 3.103; r2 = 0.9715). Approximately one-third of individuals were mature, with slightly larger lengths at 50% sexual maturity (L50) values in females than males. Diet was dominated by crustaceans, particularly deep-sea shrimps, followed by teleosts and cephalopods. A single mature female contained elasmobranch prey, representing a rare record of elasmobranch consumption. Conclusions This study has provided the first detailed life-history information for Dipturus johannisdavisi, which is regularly captured as shrimp-trawl bycatch, including reproductively active individuals, indicating vulnerability to deep-sea trawling. Implications Ongoing deep-sea trawling may pose a risk to this data-deficient species, and the data presented here provide a baseline for future assessment and management.