The sad deaths of 108 dolphins due to stranding along Cape Cod on the east coast isn’t this year’s only news of marine mammals dying in “unprecedented” numbers. The west coast is looking at a dwindling
sea otter population that is for once not due to anything humans have done.

California’s sea otter was once close to extinction after pre-Gold Rush pelt hunters left the population severely fragmented.  In 1911 an international treaty was passed to protect seals but not otters. They  wouldn't be formally protected until 1972 when Congress passed the Marine Mammal Protection Act. These laws and conservation efforts would slowly bring the population to better if not great numbers. 

Research shows the population is thinning and while scientists have a few ideas as to why it doesn’t make the news any less dismal. On Sunday the Los Angeles Times reported 335 injured, dead or sick sea otters were found last year according to the United States Geological Survey (USGS).

Tim Tinker, who has studied sea otters for over fifteen years and is a Research Wildlife Biologist at the USGS' Western Ecological Research Center, spoke with the Times and said, "We're starting to see a perplexing trend suggesting increased shark attacks on sea otters.” Sadly, the sharks are “favoring” female otters of breeding age which is also going to affect the population.

 The article said that “shark bites accounted for 15% of otter deaths in the late 1990s, but that percentage nearly doubled in 2010 and 2011.”  

 The San Jose Mercury Times also spoke with Tinker who said the great white sharks may erroneously think the sea otters are sea lions or elephant seals, attacking, and then leaving them to die when they realize their mistake. 

Other factors that are affecting the population are: infectious diseases, being hit by boats, gunshot wounds, and like dolphins they can strand.

At last count the sea otter population was at 2,711 and 379 otters short of being at the number needed for removal from the ESA's list which has the sea otter categorized as “Threatened.” The ICUN Red List places the sea otter at the “Endangered” level.

Scientists may be able to treat disease and conservationists can raise awareness about anthropogenic threats like boating accidents and ask for laws to prosecute those who wield guns irresponsibly but neither party can ask the sharks to feed with more care. Hopefully, word will get around the shark community that these aren’t the mammals they are looking for and they will cease to attack sea otters.