Abstract- Aceh is one of the largest producers of Tuna, especially YellowFin Tuna (Thunnus Albacares) in Indonesia, because it is surrounded by the Indian Ocean and Andaman Sea, and has a high selling value (KKP, 2020). Chlorophyll-a is one of the biological parameters of oceanography that plays an important role in primary productivity in the ocean. The spread of chlorophyll-a contained in phytoplantons can be used as a measure of fertility in a water. Chlorophyll-a is a green pigment found in plants that utilize sunlight to perform photosynthesis. The lack of information on the catchment area makes fishermen in aceh still use natural signs such as the presence of birds and the same catch location as the catch area. So the results of the arrest are ineffective and efficient. The content of chlorophyll-a in November was relatively high, because it was dominated by chlorophyll-a content with various variant values. Based on the results of a simple linear regression analysis that was carried out, the distribution of chlorophyll-a in November did not show a significant relationship to the catch of Yellowfin Tuna. Yellowfin tuna catches in November 2020 were only 18% and the other 82% were influenced by other factors, while in December from the analysis, there was a coefficient of determination (R Square) of 0.02, which means the relationship between chlorophyll-a and fish catches. yellowfin tuna in December 2020 was only 2% and the other 98% was influenced by other factors. Based on data taken from 12 samples of vessels using handline fishing gear, the catch of yellowfin tuna (Thunnus albacares) in November amounted to 5,864 kg in the first week of 1,446 kg, in the second week of 1,889 kg, in the third week. amounted to 896 Kg and at week 4 amounted to 1,633 Kg, and in December amounted to 3,342 kg, week 1 amounted to 1123 kg, week 2 amounted to 1,088 Kg, week 3 amounted to 783 Kg, and at week 4 amounted to 348 Kg yields yellowfin tuna catch. The distribution of chlorophyll-a in November 2020 ranged from 0.189 mg/m3 to 1.082 mg/m3, with an average content in November 2020 of 0.635 mg/m3, while in December the content of chlorophyll-a ranged from 0.101 mg/m3 to 2.568 mg /m3, with an average content in December 2020 of 1,258 mg/m3 . Catching yellowfin tuna by fishermen in November 2020 in the northern waters of Aceh Island to the south-west waters of Aceh can be said to be a potential fishing area, compared to the fishing carried out by fishermen in December 2020 in the northern waters of Sabang and the western waters of Sabang. This is supported by satellite image data on the distribution of chlorophyll-a in these water areas which is higher than satellite image data in the northern waters of Sabang and western waters of Sabang.
Keywords: Chlorophyll-a, Area of potential capture, Catch .