REDWOOD CITY (CBS/AP) — State wildlife officials were investigating why dozens of dead sharks have been washing up on the western shore of San Francisco Bay.

The California Department of Fish and Game was sending a biologist to Redwood City on Monday, where residents have been finding leopard shark carcasses littering the shoreline.

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Leopard shark die-offs are fairly common in the bay, with larger ones seen in 2006 and 2007. Experts say the causes range from release of pollutants by industry to infections.

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Sean Van Sommeran of the Pelagic Shark Research Foundation said it’s possible that Redwood City’s tidal gates played a role.

Van Sommeran said the gates control a system of lagoons and canals, and may have led to water stagnation and depleted oxygen levels.

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