Scientists believe there were hundreds of thousands of northern elephant seals inhabiting the beaches of the islands and west coast beaches of North America prior to the huge slaughter that took place starting in the early 1800s. These easily-killed elephant seals were hunted for their blubber, which was boiled down into extremely valuable oil. This oil was considered at the time to be a better mechanical lubricant than processed whale blubber.
In 1874, Charles Melville Scammon recorded in "Marine Mammals of the Northwestern Coast of America," that a bull they had killed on Santa Barbara Island yielded 210 gallons of oil.
By the late 1800's, northern elephant seals had become nearly extinct. In the same 1874 zoological study, Scammon wrote: "Owing to the continual pursuit of the animals, they have become nearly if not quite extinct on the California coast, or the few remaining have fled to some unknown point for security."