Leopard sharks along with two other species in the San Francisco Bay are dying by the thousands and environmental biologists are attempting to find out why.
Scientists say a witches' brew of bacterial, viral and fungal toxins is killing vulnerable shark populations in the Bay.
"There's probably been several thousand animals dying," said Mike McGill, a marine biologist at the Aquarium of the Bay on San Francisco's Pier 39. "We're just seeing the ones on the surface that are actually stranding on the beaches."
The Aquarium of the Bay has observation tunnels to clearly show visitors what can't be seen with the naked eye by peering into the Bay's murky waters.
Bay Leopard sharks are suffering the worst losses but they are not the only ones.
"Leopard sharks, bat rays (and) some fin fish like halibut," are dying, McGill said.
Scientists say the dying of the marine life began in the waters around the Peninsula before migrating to other areas.