Length-Weight Relationships of Eight Fish Species Collected as Bycatch from Deep-Sea Shrimp Trawls Operated in the Arabian Sea

This study establishes length-weight relationships (LWRs) for eight demersal fish species (Dactyloptena orientalis, D. papilio, Minous dempsterae, M. trachycephalus, Pterygotrigla macrorhynchus, Rogadius asper, Lythrichthys longimanus, Sorsogona tuberculata) for the first time. We collected fish specimens caught as trawl bycatch at depths of 200–420 m from Sakthikulangara fishing harbour, Kerala, India, between September 2021 and December 2022. Deep-sea shrimp trawl nets used had a mesh size ranging from 30 to 50 mm in the net body and 18–26 mm at the cod-end. Estimated b values ranged from 2.19 (Minous trachycephalus) to 3.55 (Pterygotrigla macrorhynchus). Most species deviated from the isometric growth value (b = 3), except for Dactyloptena orientalis. High coefficients of determination (r²) were obtained for the LWRs (0.94–0.97), indicating strong relationships. These LWR estimates are valuable for updating the FishBase database and understanding resource characteristics of poorly studied deep-sea demersal fishery resources in the Indian Exclusive Economic Zone (EEZ).