SAN FRANCISCO (KCBS) – State biologists say they think they know what may have killed over 100 leopard sharks in the Bay Area in recent weeks.

The scientists believe this winter’s heavy rains may have diluted Bay waters so much that it’s throwing things out of balance.

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KCBS’ Holly Quan Reports:

While preliminary necropsies found a few of the sharks suffering from internal bleeding and brain lesions, scientists surveying Bay Area lagoons saw the animals thrashing and gasping before they died, which points to some kind of environmental impact.

“They can typically survive a lot of pollutants in the water and a lot of adverse living conditions, so to see one die indicates that something has happened to the ecosystem,” said Brandy Faulker with the Pelagic Shark Research Foundation.

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A Stanford shark expert told the San Francisco Chronicle that when salinity levels fall below 19 parts per thousand, sharks will thrust their noses out of the water in order to cope. Salinity in the bay has been recorded as low as 15 parts per thousand this past spring.

Results are expected back this week of blood and tissue samples and that could support the theory of low salinity or oxygen levels.

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