Effect of climate change on the distribution of skipjack tuna Katsuwonus pelamis catch in the Bone Gulf, Indonesia, during the southeast monsoon

About 59% of Katsuwonus pelamis production of South Sulawesi Province is from the Bone Gulf. However, the threat of climate change could decline the fish production level. The purpose of this study was to identify the existence of climate change in the Bone Gulf, and to analyze the effect of the climate change on the distribution and abundance of K. pelamis during the southeast monsoon. This study used a survey method to collect two types of datasets, primary and secondary data. The primary data consisted of the fishing position, catch, in situ sea surface temperatures (SST), and chlorophyll-a, and secondary data comprised SST and chlorophyll-a obtained from satellite data of TERRA/MODIS. Ten years satellite data of 2005-2014 were used to analyze spatial and temporal of SST and chlorophyll-a anomalies, to identify the existence of climate change in the Bone Gulf. Generalized Additive Model (GAM) were used to analyze the effect of the climate change on the K. pelamis distribution using R 3.1.2 software package. All SST and chlorophyll as well as fishing data were mapped using ArcGIS 10.1. SST anomaly map in the Bone Gulf indicated that SST tended to be higher than usual over the last 10 years as mucsh as 0.5685-0.773°C especially in the Luwu Timur district waters, whereas chlorophyll-a tended to lower low tendency than usual as much as -0.2187 - -0.0659 mg m-3 particularly n the Kolaka district waters. K. pelamis catches tended to be high at the SST anomaly of -0.05-0.2°C and the fish tend to concentrate at the low anomaly of chlorophyll-a (-0.02-0.03 mg m-3). This study suggests that the low negative anomaly and the high positive anomaly of the oceanographic conditions caused the change of the distribution pattern and declining of K. pelamis catch in the Bone Gulf for the period of June-August.