Hydrographic Profiling of Temperature–Salinity Vertical Gradients in Fisheries Management Area 715, Maluku Sea, Indonesia

Suruwaky, Amir Machmud; Ndahawali, Daniel Heintje; Muhfizar, Muhfizar; Ismail, Ismail; Nuzapril, Mulkan; Gunaisah, Endang; Mustasim, Mustasim M; Ratna, Ratna; Harbani, Mestiria; Zamzami, Ilham Misbakudin Al

doi:10.21608/ejabf.2025.431574.6763

Hydrographic Profiling of Temperature–Salinity Vertical Gradients in Fisheries Management Area 715, Maluku Sea, Indonesia

Document Type : Original Article

Authors

¹ Departement of Fishing Technology, Sorong Marine and Fisheries Polytechnic, Sorong 98411, Indonesia

² Departement of Fishing Mechanization, Sorong Marine and Fisheries Polytechnic, Sorong 98411, Indonesia

³ Sorong Politeknic of Marine and Fisheries, Sorong, Indonesia

⁴ Departement of Capture Fisheries, Lampung State Polytechnic, Lampung 35141, Indonesia

⁵ Marine and Fisheries Polytechnic, Sorong

⁶ Departement of Fisheries Resource Management, Faculty of Fisheries, Muhammadiyah University of Sorong, Sorong 98416, Indonesia

⁷ Coastal and Marine Research Center Brawijaya University, Brawijaya University, Malang 65145, Indonesia

10.21608/ejabf.2025.431574.6763

Abstract

Understanding the vertical structure of temperature and salinity is essential for explaining thermohaline dynamics and supporting ecosystem-based fisheries management (EBFM) in tropical seas. The Maluku Sea, located within Fisheries Management Area (WPP) 715 of Indonesia, represents a key transition zone of the Indonesian Throughflow (ITF), where strong vertical stratification governs nutrient cycling and pelagic fish distribution. This study aimed to determine the vertical distribution patterns and gradient indices of temperature and salinity at 10-meter depth intervals across three observation blocks, Aru, Obi, and Seram. Hydrographic data were collected in February 2020 using a Conductivity–Temperature–Depth (CTD) profiler (XR-420) and analyzed using Ocean Data View software. Results show a distinct thermocline layer between 100–160m in Aru, 50–130m in Obi, and 100–210m in Seram, with the highest temperature gradient of –0.295°C/m in Aru. The halocline occurred between 100–150m, with the strongest salinity gradient (0.094 PSU/m) recorded in Seram. These patterns indicate limited vertical mixing and strong density stratification that regulate oxygen and nutrient exchange. The identified thermohaline layers correspond to potential pelagic fish aggregation zones, emphasizing their importance for sustainable fisheries management. Continuous monitoring of thermohaline structures is recommended to enhance predictive oceanographic models, support spatial planning, and strengthen data-driven EBFM implementation in eastern Indonesian waters.

Keywords