Mysterious Brain-Eating Shark Killer Identified, Though Questions Remain

           From February to July, thousands of sharks and rays washed up dead in San Francisco Bay. Exactly why had been a mystery until scientists were able to analyze DNA from some of the dead sharks.

          They found that a brain-eating parasite was crawling up their noses and eating their grey matter.

We may know what parasite was likely eating shark brains, but we still don't know why now or where exactly it came from. According to the researchers who examined the remains, it's the first case of this specific pathogen infecting wild sharks. Scientists have theorized that crowding in the bay has allowed the parasite to spread more efficiently. Higher than average rainfall could also be impacting the water's salinity, which might impact sharks' immune systems.