Abstract. Rumpa A, Najamuddin, Safruddin, Hajar MAI. 2022. Fish behavior based on the effect of variations in oceanographic condition variations in FADs Area of Bone Bay Waters, Sulawesi, Indonesia. Biodiversitas 23: 1875-1883. Fish behavior is the response of fish to conditions existing in their environment. One of the causes is oceanographic factors, which can affect the schooling movement of fish. This study aimed to identify the schooling behavior of fish based on the influence of oceanographic variations in the Fish Aggregating Device (FADs) area. Study took place from March to September 2021 in Bone Bay Waters, Indonesia. The type of research was experimental fishing with an acoustic approach for 57 times. Parameters observed were current velocity, current direction, and water temperature to the distance of schooling fish from FADs vertically and horizontally in the afternoon, evening, night, and early morning. The behavioral data of fish species were namely Decapterus russelli. The results showed namely the variation in current velocity affected the horizontal distance; variation in the direction of currents affected the horizontal distribution distance, while the water temperature affected the vertical schooling of fish. In the operation of fishing gear, especially in the early morning, in terms of the concentration pattern of schooling fish under FADs. The ideal current velocity was in the range of 0.2-0.29 [m s-1], while the ideal current direction is direct current was at the angle of 0°-60°. The schooling of fish approached to the surface and was concentrated under FADs at >30°C. Understanding on the distribution of horizontal and vertical movements and the time of concentration of fish schooling at the central point of FADs due to oceanographic variations will facilitate the effectiveness of fishing gear operation.

Abstract. Rumpa A, Najamuddin, Safruddin, Hajar MAI. 2022. Studying the relationship of immersion duration and characteristics of natural materials FAD to fish aggregation in the sea. Biodiversitas 23: 5481-5490. An understanding of immersion duration and the characteristics of natural materials Fish Aggregating Devices (FAD) on fish aggregation in the sea is crucial in developing more effective fishing strategies in FAD areas. The aim of the study was to understand the relationship between immersion duration and characteristics of FADs made from natural materials on the schooling aggregation of mackerel scad (Decapterus russelli) in the sea. The research was conducted from April 2021 to March 2022 in Bone Bay, Indonesia. The type of research was experimental fishing 78 times down at sea to observe the relationship between FAD construction and fish schools. The results demonstrated that the growth of invertebrates in the construction component of FADs based on the period of immersion in the sea at the immersion period of >30 days showed a high growth rate of algae, hydrozoa and crustacean species at the bottom of the raft. The endurance of the coconut leaves attractor at a duration of 3-4 weeks was the best condition for immersion duration in the sea because schooling fish were more concentrated around the attractor at an average distance of 1.2 m, while at a duration of 5-6 weeks the attractor had damaged and the fish schooling was less concentrated. Based on the arrival of schooling fish in FAD areas, the fastest average duration was 3-4 weeks, namely in transitional season 1. The presence of crustacean species caused fish schooling only to be concentrated at a distance of 2-3 m at the time of fishing. In the fishing strategy, the treatment of FADs using dried coconut leaves attractors showed more concentrated fish schooling and calmer fish movement pattern compared to the use of fresh coconut leaves attractor. The characteristics of the components making up FADs had a direct impact on the effectiveness of attracting and concentrating fish. In addition, the characteristics also influenced the schooling distance of fish at the center point of the FAD raft before the fishing gear was lowered.