Oceanographic factors related to Eastern Little Tuna (Euthynnus affinis) catches in the west Java Sea

Abstract

The satellite data included sea surface height anomaly (SSHA) from AVISO, sea surface temperature (SST) and chlorophyll-a (Chl-a) from Aqua MODIS and Eastern Little Tuna (Euthynnus affinis) catches were used as a combined dataset to understand the ocean variations and further addresses their relations with the Eastern Little Tuna catches in the Java Sea. The fish catches and remotely sensed data were analyzed for the 5 years datasets from 2010-2014. The relationships of oceanographic factors and catch distribution were explored with a generalized additive model (GAM). Catch rates varied temporally relatively significant over year-round. The Eastern Little Tuna catch rates have the peak season in March and October (900 ton to 1000 ton). The ELT catch peaks during the transition season from southeast to northwest monsoon (September to November) and decreases during southeast monsoon (June to August). The GAM results showed that the 3-oceanographic parameter combination models explained the highest deviance (41.4%) with Chl-a explained the highest deviance (23.3%). High probabilities of Eastern Little Tuna catches corresponded to marine productivity of Chl-a concentration ranging from 0.3-0.5 mg/m3, for SSHA ranging from 0-8 cm and SST ranging from 28-29°C. We recommend to have further investigations through the use of long-term historical time series to predict fishing ground locations and an emerging need to improve our climate understanding and forecast skill to conserve small pelagic catches.