Sea level height , sea surface temperature , and tuna yields in the Panama bight during El Niño

Between 1988 and 1998, annual tuna landings at Buenaventura (Colombian Pacific) are correlated with the sea surface temperature in the central Equatorial Pacific (r=0.78, p<0.05) and the sea level height at Buenaventura (r=0.76, p<0.05) and Balboa (Panama) (r=0.79, p<0.05). Seasonal oceanic upwelling is forced by the Panama wind jet, which may favour oceanic fisheries such as tuna. Here we first apply a bivariate correlation method (Pyper and Peterman, 1994) and then a multivariate approach (principal components analysis or PCA) to investigate the relationships of these environmental variables with landings. With the first method, we find that landing is best correlated with the sea surface temperature in the Niño 3 region, whereas the other relationships are less clear. In contrast, with PCA we find that PC1 explains 90.6% of the total variance and suggests that sea surface temperature plays a major role in determining tuna availability in the area (especially during El Niño events). Since PC2 is mainly correlated with sea level height at Balboa but only represents 6.8% of the total variance, we suggest that oceanic upwelling effects on tuna landings at Buenaventura are not significant at interannual scales.