The collapse of the massive industrial anchovy fishery in Peru in 1973 brought El Niño to the world's attention. However, small-scale (artisanal) fishermen from northern Peru and southern Ecuador were aware of this phenomenon long before this widely publicized event. They realized at least a century ago that every few years, around Christmas time, a warm water current appeared close to their desert shores; they named this current "El Niño", or "the boy child," afier the baby Jesus. The first time the term El Niño appeared was in a Peruvian newspaper in 1891, as a result of what we now know was a very strong event. Historical reconstruction (Quinn et al., 1987) of data from ship's logs, fish landings, bird populations, crop yields, among other indicators, have documented El Niño events back several hundred years, and others have argued, using proxy evidence, that El Niño has recurred over many millennium (Rodbell et al., 1999).

Afier intensive studies and data accumulation, it was discovered that El Niño was not only an oceanographic phenomenon related to the western coast of South America but a complex interaction between the ocean (sea surface temperature changes in the equatorial Pacific) and atmosphere (sea-level pressure changes in the western equatorial Pacific)—hence called the El Niño-Southern Oscillation (ENSO). ENSO is now known to impact climate patterns around the globe. Nonetheless, the Peruvian coast remains one of the areas most consistently and directly impacted by this

Handbook of Weather, Climate, and Water: Atmospheric Chemistry, Hydrology, and Societal Impacts, Edited by Thomas D. Potter and Bradley R. Colman. ISBN 0-471-21489-2 © 2003 John Wiley & Sons, Inc.

recurrent event. ENSO also has a less common, cold phase, sometimes referred to as La Niña. Except for scientists who study ENSO, most Peruvians do not differentiate La Niña from "normal" conditions. (This chapter uses the term ENSO to refer to El Niño or ENSO warm events.)

While most associate ENSO with negative impacts on flora and fauna, this cyclical climate event, which thus far has presented itself differently with each occurrence in terms of its strength, duration, and intensity, has a range of both negative and positive ecological impacts. These environmental changes trigger varied socioeconomic and political reactions that in turn may alter aspects of that society as a whole over time. In addition, society undergoes change. A changed society will then react differently to the next ENSO event. This makes planning for mid to long-term climate variability a challenging task for governments and individuals. In the last decade and a half, much effort has been put into better understanding and predicting regional climate variability associated with ENSO events, and forecasts are now being used by governments and individuals in many parts of the world in their planning efforts.

This section discusses some of the key impacts of ENSO on the fisheries sector of Peru, including a brief description of what ENSO is and the evolution of scientific interest in this phenomenon; a brief overview of the Peruvian fisheries sector, with examples of impacts from the 1997-1998 ENSO event; and policy implications of ENSO-related climate forecasts.

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