Study on Health Condition of Lutjanus gibbus during Transition Season in the Alas Strait, Indonesia

Abstract

The Alas Strait is one of the major fishing grounds in West Nusa Tenggara Province, Indonesia, and supports commercially important fisheries resources, including Lutjanus gibbus (humpback red snapper). Increasing fishing pressure on this species has raised concerns over the long-term sustainability of its stock in the region. This study aims to evaluate the stock status of Lutjanus gibbus based on length distribution and SPR values. Data were collected from March to May 2025 at the Tanjung Luar Fish Market, East Lombok Regency, using accidental sampling on 221 individuals. Length-frequency analysis was conducted using Microsoft Excel and compared with the length at first maturity (Lm) obtained from the Scientific Forum for Sustainable Fisheries Management of West Nusa Tenggara Province. Stock status was further evaluated using the Length-Based Spawning Potential Ratio (LBSPR) approach through the Barefoot Ecologist’s Toolbox. The results showed that 84% of the sampled individuals were below the length at first maturity (<Lm), whereas only 16% exceeded the maturity threshold (>Lm). The dominant size class ranged from 25.8 to 29.3 cm in total length, indicating that the catch composition was dominated by immature individuals. The SPR analysis yielded a value of approximately 10%, indicating that the stock status of Lutjanus gibbus in the Alas Strait during the first transitional season was overexploited. These findings demonstrate that current fishing activities predominantly exploit immature individuals and may threaten long-term stock sustainability. Therefore, management measures regulating fishing activities during March–May are necessary to support the sustainable utilization of Lutjanus gibbus resources in the Alas Strait.