I have never heard this. Is it on one of their maps from the 1960s?
I was curious about the San Diego Zoo and whether it has history with sea otters. I didn't find any info on that, but I did find an article from October 2011 about a wild sea otter showing up in San Diego. The article speculates that sea otters may be showing up there more often as they expand their range down California's coast into their former habitat. http://www.utsandiego.com/news/2011/oct/09/rare-sea-otter-spotted-san-diego-waters/