Peruvian Fisheries and El Nino
One of the world's richest fisheries is off the coast of Peru. In most years winds from the southeast push warm surface water away from the coast. In its place, upwelling brings to the surface cold water rich in nutrients. These provide nourishment for the microscopic plants know as plankton.
Plankton normally provide food for a vast community of anchovies and other fish.The fish in turn supply food for seabirds. Not only is the fish catch economically important, but the harvesting of bird excrement (guano) provides a supply of valuable fertilizer.
Every few years the pattern of air circulation of the equatorial Pacific changes in a way that affects oceanic upwelling. This weather condition is known as El Niño. During El Nino, upwelling brings up warm water with few nutrients. A serious economic consequences of El Niño is its devastating effect on the Peruvian anchoveta fisheries. Populations of fish and seabirds vanish and anchovy catches dwindle during El Niño. (See our El Niño page.)
Some biologists fear that the over fishing of the anchoveta by humans, plus the eating of anchovies by large fish and seabirds, combined with the injurious effects of an intense El Niño episode, like the one in 1997-98, could reduce the anchoveta stock to such critically low numbers that recovery could be difficult. The 1972-73 El Niño caused a serious drop in the fish catch which took years to recover. Since then, the Peruvian government has worked hard to regulate fishing in their territorial waters. Fortunately they have been succesfull, and the fishery has recovered from even severe El Niños like the one in 1988-1989.