The new study by researchers at the Scripps Institution of Oceanography, led by Ryan Rykaczewski and David Checkley, suggests atmospheric wind forces can determine the availability of microscopic organisms that sardines and anchovies feed upon. When wind causes nutrient-rich waters to rise to the surface, plankton levels increase and sardine populations flourish, the scientists said. Conversely, sardine numbers crash when plankton becomes scarce as wind conditions change.

The scientists said their findings might explain the sardine and anchovy booms and busts off California's coast and could also explain similar population cycles elsewhere around the world.

"This paper is the first to show a mechanistic relationship between climate variability and the sardine fishery," said Rykaczewski, a Scripps graduate student researcher. "There have been a lot of hypotheses about climate change and sardine and anchovy fisheries, but there has been little scientific support for a mechanism connecting changes in climate to changes in these fish populations."

The study is reported in the Proceedings of the National Academy of Sciences.