Optimizing chlo and sst for skipjack tuna fisheries in the banda sea and its surroundings using GAM and ECDF

¹ Faculty of Fisheries and Marine Sciences (FIPK) Hasanuddin University, Jl. Perintis Kemerdekaan, KM 10 Tamalanrea, Makassar, Indonesia 90245
² National Research and Innovation Agency (BRIN), Gedung B.J. Habibie, Jl. M.H. Thamrin No. 8, Jakarta Pusat 10340, Indonesia

^* Corresponding author: suna032@brin.go.id

Abstract

This study aims to determine the optimal values of chlorophylla (Chlo) and Sea Surface Temperature (SST) for skipjack fishing (Katsuwonus pelamis) in the Banda Sea and its surroundings using the GAM model and ECDF function. The GAM model yields the formula CPUE = 33.07 + s(Chlo, edf = 7.14, Ref.df = 8.09) + s(SST, edf = 8.95, Ref.df = 8.99), with a significant value for Chlo of 0.58 mg/m³ and an SST of 28.26°C, as well as the highest CPUE value of 51.84. Due to the low performance of the GAM model, ECDF is used to determine the optimal values of Chlo and SST. The results of the Kolmogorov-Smirnov test on the ECDF value showed a p-value for Chlo of 0.0016 and SST of 4.45e-14 (p < 0.05). Thus, there was a significant difference between the f(t) and g(t) distributions at Chlo = 0.28 mg/m³ and SST = 30.57°C. K-Means analysis shows that the optimal value range for Chlo is 0.075 - 0.33 mg/m³ and for SST is 29.47 - 30.47°C. The optimal months are January to June as well as October, where the combination of SST and Chlo concentrations reaches levels that support the productivity of skipjack fishery. However, from July to September, lower SSTs begin to dominate, which can reduce fishery optimality, although some regions still have supportive Chlorophyll. In November and December, SSTs reach very high levels, potentially reducing productivity efficiency.