RBMO 45 - Suppl. 1: 705-722.
Article

El Niño induced changes of the coastal fish fauna off northern Chile and implications for ichthyogeography

Walter Sielfeld¹, Jürgen Laudien², Mauricio Vargas³ and Mario Villegas^1†

¹Universidad Arturo Prat, Av. Arturo Prat 2120, Iquique, Chile
²Alfred Wegener Institute for Polar and Marine Research, P.O. Box 120161, 27515 Bremerhaven, Germany
³Servicio Nacional de Pesca, Pasaje Alessandri 470, Of. 110, Iquique, Chile
^†Deceased in March 2008 

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The coastal fringe off northern Chile (18º-23ºS) is inhabited by numerous neritic fish species of which 249 are commonly observed during normal and cold La Niña (LN) conditions. During El Niño (EN) the ichthyofauna of northern Chile changes significantly due to about 100 invading fish species normally inhabiting lower latitudes, named “septentrional invaders” and “tropic-equatorial fishes”. This results in a composition including 15 fish families and 86 genera. Analyses showed that species affected by EN were not the same between the last three EN events revealing that only the epipelagic species Anchoa naso, Albula vulpes, Atherinella nocturna and Scomberesox saurus stolatus behaved consistently. Off northern Chile, EN 1982/83, 1986/87, 1991/92, 1997/98, 2002/2003 and the not clearly EN defined 2004/2005 period with their aligned thermal abnormalities of each particular event were directly related to the number of invading/affected species. Most of the alien species (>50%) were epipelagic, 25% were typical for sandy beaches and 14.6% for rocky shores. The shore fish community did not show major changes during and after EN events, as only a few invading species were recorded; just Umbrina xantii was found during all events considered. In order to understand the response of the fish community to ENSO events a biogeographical analysis of 721 fish species reported for neritic habitats (coastal epipelagic and benthic) distributed between 0°-57°S (Gulf of Guayaquil to Cape Horn) was made. Their distribution ranges for normal oceanic conditions were taken from the very numereous existing literature. It is concluded that the north/south migration of Panamic and Peruvian warm water fishes during EN/LN events along the north Chilean coast between 18º-23ºS, indicates that it represents a wide transition zone between the Peruvian and the Chilean ichthyogeographic provinces.

Key words: ENSO, neritic fishes, northern Chile, ichthyogeography

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