Dozens of leopard sharks have been washing up dead in California since April, and now a necropsy shows at least one of the sharks died of massive internal bleeding, such that blood was even coming out of the shark's skin, according to a Daily News report.

The necropsy, conducted by the California Department of Fish and Game, uncovered "inflammation, bleeding and lesions in the brain, and hemorrhaging from the skin near vents." According to the Daily News story, bleeding was additionally detected around the tested female's other internal organs.

The results suggest the 50 sharks that have washed up dead at Redwood Shores in Redwood City, California, since April must have died a slow and agonizing death.

Catherine Greer, a resident of the city, said she and her son tried to save some of the sharks by returning them to the water, but "they'd swim right back, thrashing their heads against the shore ... as if they were trying to commit suicide."

I've been to this spot before and have seen presumably healthy leopard sharks right along the shore. You can see one in this video:

key question then clearly remains: What is causing the internal bleeding?

As of now, that's still a mystery. A statement released by the Silicon Valley city mentioned, "The...pathologist is not drawing any conclusions until more examinations and all tests are performed."

A bacterial study and microspoic tissue analysis are underway. Investigators have not ruled out a human-caused spill of toxic chemicals, although no big spill has been reported in the region over the past couple of months.

Sean Van Sommeran, executive director of the Pelagic Shark Research Foundation in nearby Santa Cruz, suspects "we're only seeing a tiny fraction of what's going on," meaning more sharks and other animals are likely being affected by the problem.

Van Sommeran added that leopard sharks are typically a "pretty resistant" species.

I have to wonder...If whatever is in the water is doing this to a sturdy shark, what in the world is it doing, or could it do, to us? Perhaps the cause is shark-specific, such as a pathogen affecting only leopard sharks, but I'd like to see the proof.