Length–Weight Relationship of Nine Elasmobranch Species Landed along the South Tamil Nadu Coast, India

Kishorekumar, M.; Jayakumar, N.; Jawahar, P.; Neethiselvan, N.; Padmavathy, P.; Karuppasamy, K.; Sudhan, C., and Chandravanshi, S., 2024. Length–weight relationship of nine elasmobranch species landed along the south Tamil Nadu coast, India.The present study was conducted to establish the length–weight relationship of nine elasmobranch species from the coast of southern Tamil Nadu, India. In total, 2686 specimens of nine species of elasmobranchs belonging to five orders, seven families, and eight genera were collected fortnightly from commercial catches with different fishing gear, such as trawl net, gill net, and deep-sea longline, from the Thoothukudi, Mandapam, and Thengapattanam fishing harbors from December 2022 to November 2023. The results showed that most species exhibited positive allometric growth and that values of b were within the expected range of 2.5 to 3.5. The maximum b value (3.17) was observed for male Pateobatis bleekeri. The total length–weight relationship or disc width–weight relationship showed good fit with r2 values, varying from 0.8374 to 0.9969. The calculated b values in the current study showed that all males, females, and combined sexes of P. bleekeri, Aetobatus ocellatus, and Acroteriobatus variegatus showed negative allometric growth (b < 3). In the study, a new maximum total length is reported for P. bleekeri, and this study provides the first estimate,, of the length–weight relationship for the critically endangered species A. variegatus. The study provides baseline information for biological studies, stock assessment and management, and conservation of elasmobranch resources in a sustainable way along this coast.