Analysis of Synergistic Oceanographic Factors Influencing Seasonal Whale Shark (Rhincodon typus) Appearance in Botubarani Waters, Gorontalo Bay, Indonesia

This study aimed to analyze the influence of marine environmental parameters on the occurrence of whale sharks and to identify seasonal differences in their appearances. Data were collected monthly from June 2023 to May 2024, covering sea surface temperature (SST), current speed, chlorophyll-a concentration, and the number of whale shark sightings. SST and chlorophyll-a data were obtained from MODIS-Aqua satellite imagery, while current speed was modeled using the FM Flow Model module in MIKE 21 software. The analysis was conducted seasonally (Eastern monsoon, transitional season II, western monsoon, and transitional season I) over the same one-year period. Statistical methods included Pearson correlation, multiple linear regression, one-way ANOVA, and Tukey’s HSD post-hoc test. The results indicated that chlorophyll-a concentration had a significant positive correlation (r= 0.63; P< 0.05) with whale shark sightings, while current speed exhibited a significant negative correlation (r = -0.63; P< 0.05). The multiple regression model accounted for 59.5% of the variation in sightings (R² = 0.595). Tukey’s HSD post-hoc analysis revealed a significant difference only between the eastern monsoon and transitional season II (P = 0.025), with the eastern monsoon representing the peak occurrence period. During this time, sightings increased by an average of 1.37 individuals per day compared to transitional season II. This peak occurred under optimal SST conditions ranging from 27.5 to 28°C, chlorophyll-a concentrations between 0.58 and 1.83mg/ m³, and relatively low current speeds of 0.11 to 0.13m/ s. These findings provide a scientific basis for managing whale shark conservation and protection areas in Botubarani Waters, Gorontalo Bay, and support an adaptive approach to whale shark tourism management.