Size distribution and seasonal fishing patterns of tuna (Katsuwonus pelamis and Thunnus albacares) in troll line fisheries at PPN Ambon, Indonesia

Tuna fisheries in Indonesia, particularly in the Ambon region, represent a vital sector that supports food security and the local economy; however, information on size distribution and seasonal fishing patterns in troll line fisheries remains limited. This study aims to analyze the size distribution, fishing season, and fishing grounds of yellowfin tuna (Thunnus albacares) and skipjack tuna (Katsuwonus pelamis) caught using troll lines and landed at the Nusantara Fisheries Port (PPN) Ambon. Troll lines are traditional fishing gear effective for catching pelagic fish, especially tuna, as they are operated during the day in accordance with the feeding behavior of the fish. The study was conducted from September 2024 to February 2025 using catch recording methods, field observations, and interviews with fishermen. The data were analyzed descriptively and presented in graphs and tables. The results showed that the size of skipjack ranged from 46.1 to 56.3 cm, with the maximum size recorded in November and the minimum in December. The peak fishing season for skipjack occurred between September and November. The yellowfin tuna caught were classified as baby tuna, ranging in size from 46.9 to 60.7 cm, with the largest size recorded in November and the smallest in October. The peak fishing season for yellowfin tuna was from October to December. Most of the fishing activities took place in the Arafura Sea compared to the Banda Sea. These findings provide valuable information for fishers and stakeholders in designing effective and responsible fishing strategies, as well as preventing the capture of undersized fish.