Title: Beyond size: Assessing the status of three elasmobranchs in Sri Lankan waters using length-based spawning potential ratio.

The status of three elasmobranch species, Carcharhinus falciformis, Neotrygon indica, and Glaucostegus granulatus, in Sri Lankan waters was assessed through a comprehensive study incorporating biometric analyses and assessment using the length-based Spawning Potential Ratio (LBSPR). Biometric analyses included examining length-frequency distributions, length-weight relationships, and maturation data (L₅₀ and L₉₅) for all species. Notably, this study provided the first investigation into the biological aspects of N. indica and G. granulatus in Sri Lankan waters. Trained researchers collected biometric data (length, weight, and sexual maturity) of all three study species from November 2017 to December 2023. The length-weight relationships revealed a positive allometric growth pattern (b > 3) for all three species. The study estimated L₅₀ to be 196.5 cm for male (n=370) C. falciformis. For N. indica, the estimated L₅₀ was 34.1 cm for females (n=76) and 30.2 cm for males (n=2,356). For G. granulatus, the estimated L₅₀ was 82.2 cm for females (n=45) and 68.6 cm for males (n=288). The study revealed that high fishing pressure has resulted in an overfished condition for both C. falciformis and N. indica, with the mean spawning potential ratios (SPR) being below the limit reference point of 20% SPR. For C. falciformis, the SPR was 7%, indicating overfishing, while for N. indica, the SPR ranged from 14% to 27% from 2018 to 2023, with the 2023 value exceeding the limit reference point. A stock rebuilding strategy would be required to increase the spawning stock biomass of both species. Potential management strategies for the conservation of elasmobranch populations in Sri Lankan waters include implementing a minimum legal size for harvest, establishing marine protected areas, and implementing effort controls.