RBMO 46(2): 231-242 | 2011
Article 

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El Niño Southern Oscillation and spatial-temporal variability of the nominal performances of swordfish (Xiphias gladius) in the southeastern Pacific

Fernando Espíndola^1*, Eleuterio Yáñez² and María Ángela Barbieri^1,2

¹División de Investigación Pesquera, Instituto de Fomento Pesquero, Blanco 839, Casilla 8V, Valparaíso, Chile

²Pontificia Universidad Católica de Valparaíso, Casilla 1020, Valparaíso, Chile

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Swordfish (Xiphias gladius) is a highly migratory pelagic species, found in tropical, subtropical and temperate regions. In the Pacific Ocean, several studies have linked their wide latitudinal distribution (50ºN-50ºS) to environmental variables, since food is abundant along the frontal zones where currents or water bodies converge. In the southeastern Pacific, the subtropical anticyclone positively forces ocean temperatures along the west coast of South America, decreasing pole ward from the subtropical latitudes due to the El Niño Southern Oscillation. Environmental data from remote sensing enabled us to study changes in the spatial position of the 18ºC isotherm in relation to spatial-temporal changes in swordfish nominal fishing yields (CPUE) of industrial longline fleet in the coast of Chile. Correlations were obtained between the latitudinal gravity center (LGC) of CPUE and the latitudinal position of the 18ºC isotherm, between the latitudinal position of the 18ºC isotherm and the area bounded by the 17ºC isotherm, as well as between El Niño 12 index and the latitudinal position of the 18ºC isotherm. At a seasonal level, the 18ºC isotherm moves south of 37ºS at the beginning of the year, reaching 25ºS in August. This pattern occurs in a similar way to the area bounded by the 17º and 18ºC isotherm. Two phases were observed in the swordfish CPUE, with 0.65 ± 0.06 kg per hook since mid-April to early June, and 0.37 ± 0.05 kg per hook from early September until late November.

Key words: CPUE, isotherm, El Niño 12 index, remote sensing

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