These were hunted into extinction. In the 1800's there were possibly 50,000 of them. They were killed by the thousands. Their skin was used for leather, their whiskers as pipe cleaners, and they were turned into lamp oil. Apparently their meat wasn't exactly good tasting, so they weren't killed to be used for food. By the 1940's they were so scarce that all the commercial hunting was stopped, and only a few were around, possibly until 1974.
Sea Lions are actually what got me to buy a digital camera. I was really rather late venturing into digital because I was happy with film. Oregon has the largest natural sea cave in America, called the Sea Lion Caves. We took our kids there, and right before going into the cave I had been taking pictures of my kids on the beach in the sunshine. The cave, being a cave, is not surprisingly rather dark. For those who don't know film or regular photography, there is the speed of the film (ISO), and that in essence increases the amount of light that gets processed. What happened was I had a film meant for a very light scene and then I went into a very dark scene. To get pictures of the sea lions I had to do a long exposure or change my film only a few pictures into a roll, wasting the rest of the roll. With digital you can adjust it much easier than changing film out. I still love film, and use it, but I decided to go digital to allow me to be able to go from dark interiors to brightly lit exteriors while following my kids. Amazingly the picture of the sea lions in the cave came out pretty well, because one thing sea lions do well is hold still when they are comfortable.