Growth, Mortality, and Stock Status of Bigeye Scad Selar crumenophthalmus in the Natuna Sea, Indonesia

The bigeye scad (Selar crumenophthalmus) is a commercially significant small pelagic species in Indonesia's Fisheries Management Area (FMA) 711, a region facing increasing fishing pressure and declining catch rates. This study provides the first quantitative stock assessment for this species in the Natuna Sea to establish a scientific basis for management. Length-frequency data from 6,511 individuals were collected monthly from March 2019 to November 2021 from commercial purse seine landings and were analyzed using the TropFishR package with the electronic length frequency analysis (ELEFAN) method. The results indicated a fast-growing population with an asymptotic length (L∞) of 26.18cm and a growth coefficient (K) of 0.87 year⁻¹. However, the stock is under intense pressure, with fishing mortality (F=2.03 year⁻¹) being nearly double the natural mortality (M=1.07 year⁻¹). This has led to an unsustainable exploitation rate (E=0.65) and has depleted the spawning stock biomass to a critical level, with a spawning potential ratio (SPR) of just 19%, below the 20% limit reference point. This study concludes that the bigeye scad stock is experiencing severe growth overfishing and is at high risk of recruitment overfishing, threatening the long-term viability of the fishery. Urgent management interventions are imperative, focusing on reducing fishing mortality through effort controls and increasing the size at first capture via gear modifications to rebuild the spawning stock and to ensure the sustainability of this vital resource.