Distribution of Chlorophyll-a Concentration in Biak Numfor Waters and Its Impact on Bullet Tuna Catch (Auxis rochei Risso, 1810)

This study was conducted with the aim of examining the distribution of chlorophyll-a concentration and its effect on the production of tuna catch to achieve optimum fish catch in the waters of Biak Numfor Regency. This study employed experimental fishing techniques from April to July 2023, collecting data on catch volumes and satellite imagery to assess the distribution of chlorophyll-a concentration based on fishing position plots. The data analysis commenced with GIS techniques to extract and map the temporal distribution of chlorophyll-a in the study area, followed by a composition analysis of the catch. Statistical analyses were then performed to explore the effects and relationships between chlorophyll-a concentration and bullet tuna catch volumes. The findings revealed significant fluctuations in chlorophyll-a concentrations in the waters of Biak Numfor from April to July 2023, with minimum and maximum values of 0.16 and 0.42mg m⁻³, respectively, and an average concentration of 0.32mg m⁻³. Regression analysis demonstrated a significant impact of chlorophyll-a concentration on bullet tuna catch, with an F-value of 82.834 and a significance level of 0.00. The coefficient of determination (R²) was calculated at 0.58, while GAM analysis confirmed a highly significant relationship between the two variables (P<0.0001). Correlation analysis further supported these findings, yielding an r-value of 0.762, indicating a strong positive correlation between chlorophyll-a concentration and bullet tuna catch. Notably, cross-correlation analysis showed that the presence and increase in bullet tuna production in the waters of Biak Numfor were particularly pronounced during the 17th fishing trip.