Length-Weight Relationships of Eight Pelagic Fish Species Caught by Drift Longlines in the Gulf of Mannar, India

Vasanth, K.; Muthupandi, K.; Naganandhini, V.; Radhakrishnan, K., and Narayanan, M., 2025. Length-weight relationships of eight pelagic fish species caught by drift longlines in the Gulf of Mannar, India. Journal of Coastal Research, 41(3), 510–515. Charlotte (North Carolina), ISSN 0749-0208. The length-weight relationships were estimated for eight pelagic species caught in the Gulf of Mannar, India, using experimental longlines. The experimental study was conducted from January to October 2022 in fortnightly intervals using longlines (3000 m for needlefish and 11,250 m for carangids), each equipped with 600 “J”-type fishing hooks of various types (straight, reversed, kirbed). The hook numbers used were standard sizes that ranged from 8 to 11 for both groups (needlefish and carangids). The longlines were fabricated with polyamide monofilament and operated from 1 to 2 m depth for needlefish and 20 to 25 m depth for carangids for 3 to 5 hours for both longline units. Overall, 21,150 hooks were deployed in 24 fishing trials for each experimental longline. A maximum total length was recorded for four needlefish species, Strongylura strongylura (80), Tylosurus choram (91), Tylosurus crocodilus (97), and Ablennes hians (96), and four carangids species, Caranx bajad (60.5), Alectis indicus (62), Caranx ignoblis (69), and Scomberomorus commerson (74). In terms of growth, the length-weight relationships revealed positive allometric growth (b >3) for three species of carangids, C. bajad, S. commerson, and A. indicus (p < 0.05) and negative allometric growth (b <3) for four species of needlefishes, T. choram, S. strongylura, T. crocodilus, and A. hians, and one species of carangid, C. ignoblis.