State scientists say, this time of year, they typically come across six injured or dead otters bitten by great white sharks along the central coast. Last month they found 19…a record.
Mike Harris with the California Department of Fish and Game says most of the otters had a single bite mark.
"There's never soft tissue removed, there's never any indication of a secondary bite. We describe these events as being an investigative bite."
He says once the sharks realize they're not biting into their preferred prey of seals or sea lions…they move on. White sharks like cold water and some researchers believe the cooler-than-average ocean temperatures from an unusually mild summer have helped trigger a boom in the shark population along California's central coast.
But sharks aren't the only threat.
"Otters are getting hit from a bunch of different angles. We also have a fair amount of mortality that seems to be related to exposure to land-sea pollutants."
Department of Fish and Game wildlife veterinarian Melissa Miller says specifically blue-green algae. It's toxic to sea otters.
Miller say bacteria from the algae flows into Monterey Bay from nearby lakes and rivers and contaminates the sea otters' food sources. She says the bacteria is tied to more than 20 otter deaths over the past few years.