Variations in chlorophyll-a concentration and the impact on Sardinella lemuru catches in Bali Strait, Indonesia

The variation of chlorophyll-a concentration during 2003–2007 was studied in Bali Strait, Indonesia, using Aqua-Modis satellite data, and their relationships with catch per unit of effort (CPUE) of Sardinella lemuru, sea surface temperature (SST) and indices of climate variability (Niño 3.4 and Indian Ocean Dipole Mode Index) were analyzed. An inverse relationship was found between SST and chlorophyll-a anomalies. Chlorophyll-a anomalies significantly increased at the end of 2006, reaching 1 mg/m3 above normal. This increase corresponded with upwelling processes represented by a drop of SST during the El Niño event that coincided with changes in the Indian Ocean Dipole at the end of 2006. There was an unlagged response between chlorophyll-a and SST. However, there was an integrated response between chlorophyll-a and the CPUE of S. lemuru, such that increased catches (and CPUE) of S. lemuru were most highly correlated with increased chlorophyll-a in the prior three months.