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  D. How El Niño and La Niña Events Affect Deep Sea Fish Populations

Narrator: This is Science Today. Deep-sea fish populations have tripled in the last fifteen years. Researcher David Bailey of the Scripps Institution of Oceanography at the University of California , San Diego , says the upsurge appears to be driven by an increase in food available to the animals living in the vast, dark plains at the bottom of the ocean.

Bailey: The animals that live on the bottom of the ocean, they get the vast majority of their food from the surface. The vast majority of it falls down as a rain of particles called marine snow, which is basically dead plankton raining down from the surface.

Narrator: Bailey explains that anything that changes the productivity of the surface waters, changes how much food reaches the ocean floor.

Bailey: And El Niño, La Niña and these longer term cycles, they all change how much plankton grows by changing nutrient availability. And what this study shows is that when deep sea fish are left alone, they show large changes in their abundance. These are driven by natural factors, such as oceanographic and climatic changes. And that shows the difference between natural changes and those which are driven by fishing.

Narrator: For Science Today, I'm Larissa Branin.