Population Dynamic and Spawning Potential Ratio of Indian Mackerel Rastrelliger kanagurta (Cuvier 1817) in the Aru Sea, Indonesia

The Indian mackerel (Rastrelliger kanagurta) holds significant economic value in Indonesian fisheries. However, the continued increase in fishing activities may impact its population, leading to a decline. Therefore, studying the population dynamics and the spawning potential ratio (SPR) using a length-based data approach is essential to determine population parameters and to assess exploitation status. This research was conducted in 2021, with fish length measurements collected from mini purse seine vessels operating in the Aru Sea and landing their catches in Kaimana, West Papua, Indonesia. The results showed that the length distribution of the Indian mackerel ranged from 10 to 31.5cm fork length (cmFL), with a mode at 22.5 cmFL. The asymptotic length (L∞) was estimated at 33.08 cmFL per year, while the growth rate (K) was 0.8 per year. The natural mortality rate (M) was 1.55 per year, and the fishing mortality (F) was 1.04 per year, resulting in a total mortality rate (Z) of 2.59 per year. The exploitation rate (E) was 0.4. The exploitation level of the Indian mackerel in the Aru Sea is still moderate, indicating that increasing fishing effort or the number of fishing gears is still possible. The estimated length-based SPR (LB-SPR) was 57%. The spawning potential ratio of mackerel in the Aru Sea exceeds the minimum reference point, and the target reference point suggests that its exploitation is still sustainable. This indicates that further development efforts can be pursued.