Scores of Dolphin Deaths Have Scientists Baffled

Though the dolphin die-off has be attributed to a virus, the cause of the disease remains a mystery.

Since late last year, four or five dolphin carcasses have beached in Brazil each day. Scientists have confirmed that a virus is to blame, but the mortalities still have conservationists baffled.

The Associated Press reports more than 130 gray dolphins have washed up in the Bay of Sepetiba, a coastal area about 45 miles west of Rio de Janeiro, since late November. Another 40 dolphin carcasses were found on the neighboring island of Ilha Grande. Combined, that's more than 20 percent of the area's known dolphin population, which, at an estimated 800, may be the highest concentration of the species in the world.

Local conservation NGOs like the Boto Cinza Institute and SOS Botos have examined

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