SAN FRANCISCO - Leopard sharks in particular have been dying off in record numbers in San Francisco Bay.
The sharks have been found near Hayward, Foster City, Berkeley, Oakland and Redwood City.
A leopard shark was recently caught on video as it entered its death throes. The problem began seven weeks ago and shows no signs of going away.
The high numbers of sharks dying is keeping Sean Vansommeran extremely busy.
"The conservative estimates are in many hundreds at this point," Vansommeran said.
He runs the Pelagic Shark Research Foundation, which has a Facebook page dedicated to documenting and solving the largest die-off of leopard sharks since the 1960's, and they're not alone.
"Leopard sharks, bat rays, and other important fish like halibut," Vansommeran said.
Research so far points to a pathogen getting into the brains of the sharks.
"Well the pathogens get into the eyes, nose duct, they have a brain infection Causes hemorrhage," Vansommeran said.
The best theory on the cause is that it is a product of our prolonged drought, followed by this season of heavy rains falling on land, washing material into the Bay.
"So then when it rains it scours the land and puts a triple dosage of whatever it is in the watershed."
So if you see a dead fish on the shoreline, or perhaps a dying one offshore, know that it is not alone.
Anyone who sees one can take a photo, get GPS coordinates of the location and contact the department of fish and wildlife, or Sean on his Facebook page.