Stock Assessment of Nemipterus marginatus in Java Sea: Case Study on Batang Regency and Pati Regency (Early View)

Abstract

This research examined the expolitation status of Nemipterus marginatus in the coastal waters of Pati and Batang Regencies, Central Java Province. Field surveys were conducted from April to September 2025 to measure the total length and body weight of 226 specimens collected from Pati and 391 specimens from Batang. The length–weight relationship of N. marginatus in Pati and Batang show negative allometric pattern, with W = 0.134L^2.15 and W = 0.052L^2.471, respectively. The Lc₅₀_% values were 11.61 cm in Pati and 10.90 cm in Batang. Growth parameters for N. marginatus in Pati were L∞ = 26.0 cm, K = 0.40 year⁻¹, M = 1.02 year⁻¹, F = 0.76 year⁻¹, Z = 1.78 year⁻¹, and E = 0.43, indicating a sustainable level of exploitation. Meanwhile, in Batang, L∞ = 26.0 cm, K = 0.58 year⁻¹, M = 1.30 year⁻¹, F = 1.40 year⁻¹, Z = 2.70 year⁻¹, and E = 0.52 (overexploitation). The estimated Maximum Sustainable Yield (MSY) was 3.286 tons (IDR 29.574 million) in Pati and 3.589 tons (IDR 32.302 million) in Batang. The recruitment season was estimated to occur from February to July in Pati and from February to June, with secondary peaks in September and November, in Batang. These findings indicate that N. marginatus populations in the northern waters of Central Java are approaching optimal exploitation levels. Hence, management strategies should consider the size limits and seasonal fishing regulations to promote stock sustainability.