Variation in Eastern Little Tuna (Euthynnus affinis) catches related to El Niño Southern Oscillation (ENSO) events in the Makassar Strait

Abstract

In order to determine how the El Niño Southern Oscillation (ENSO) affects Eastern Little Tuna catch rates in the Makassar Strait (MS), satellite-derived oceanographic variables, including sea surface temperature (SST), chlorophyll-a, salinity, sea surface height (SSH), ocean current, Niño index 3.4, and Eastern Little Tuna (Euthynnus affinis) catch data were used. Analyses were conducted for a seven-year period (January 2015-December 2021), which included the El Niño (2015) and La Niña (2021) events. A higher CPUE value is obtained in 2021 when La Niña occurs with a CPUE value of 3973 kg/trip, compared to the El Niño event. Based on seasonal variations, the highest catch was recorded during the northwest monsoon (706.02 kg/trip) with 2789 fishing points, while the lowest occurred during the southeast monsoon (700 kg/trip) with 2942 fishing points. The CPUE was 16.25 kg/trip with 1133 fishing points during El Niño and 23.56 kg/trip with 1027 fishing points during La Niña, respectively. The fishing grounds area was wider during the La Niña period, at 2 - 8°S and 115 - 120°E. This study revealed a strong impact of the La Niña events, significantly increasing Eastern Little Tuna catch in the MS.