Integrating harvest analyses into demographic analysis of silky shark (Carcharhinus falciformis) in the Indian Ocean

Given the current uncertainty regarding the population status of silky sharks (Carcharhinus falciformis) in the Indian Ocean, this study aimed to provide a preliminary understanding of their population status and structure in the region by conducting demographic and harvest analyses. Six scenarios were developed to assess the effects of uncertainty in survival estimates on key demographic parameters, incorporating region-specific growth and age-at-maturity data, and considering reproductive cycles of 1 and 2 years. Monte Carlo simulations were employed to estimate the intrinsic rate of population increase (γ), net reproductive rate (R0), generation time (G), population doubling time (tx2), and steepness (h). The results showed that the γ ranged from 0.056 to 0.276, and h ranged from 0.354 to 0.689. Scenarios with lower age at maturity and shorter reproductive cycles exhibited higher growth rates and shorter doubling times, indicating greater population resilience. Additionally, the study highlighted the significant impact of harvest selectivity on population sustainability, demonstrating that higher harvest selectivity for younger individuals reduces the available population for exploitation. Adjusting fishing gear selectivity to reduce the capture of younger age classes could help maintain optimal population growth and support long-term conservation. These findings emphasize the importance of incorporating multiple scenarios and uncertainties into population assessments to inform effective management and conservation strategies.