Polluted rain poisoning fish stocks

Mercury spilled into the air from polluting industrial centres travels thousands of miles before raining into the oceans to poison fish, according to scientists.

The findings suggest that levels of the toxic metal in edible fish is likely to rise in the coming decades.

Even small amounts of mercury can damage nerves and be harmful to the heart and digestive and immune systems. US scientists suspect mercury in the tissues of deep-living North Pacific fish caught near Hawaii originated in Asian industrial centres. After being blown downwind, the mercury was deposited into the ocean in rainfall. Bacteria then processed it into methylmercury, the form that accumulates in fish.

“The implications are that if we’re going to effectively reduce the mercury concentrations in open-ocean fish, we’re going to have to reduce global emissions of mercury, including emissions from places like China and India,” said researcher Professor Joel Blum of the University of Michigan.