Climate influence on oil sardine and Indian mackerel in Southeastern Arabian sea

The anomalies of sea surface temperature, coastal upwelling index, rainfall, multivariate ENSO index and chlorophyll a were analysed and correlated with catch rate anomalies of oil sardine and Indian mackerel exploited by purse seine along the coastal waters off Karnataka, India in South-Eastern Arabian Sea during period 1990–2014. The purse seines in Karnataka contributed on an average 75% and 65% catch of oil sardine and Indian mackerel respectively. The catch rate anomalies of oil sardine, showed a significant positive correlation with sea surface temperature and negative statistical correlation with multivariate ENSO index. Such significant relationship was not observed in the case of Indian mackerel. The relationship of those parameters to variations in catch distribution of oil sardine and Indian mackerel was explored with a generalized additive model. The GAM results indicated that for sardine, sea surface temperature ( R–sq = 0.339) with 40.8% deviance and for mackerel, chlorophyll a (R–sq =0.419) with 58.9% deviance were better than other climatological factors and can be considered as a climatological predictor of catches in the region. The study also indicated a combination of sea surface temperature and multivariate ENSO index anomalies had better deviance of 56% for oil sardin