What's with the yellow tags? 

A sea lion that shows up at PIER 39 with a yellow tag has come a long way. As previously mentioned, orange tags indicate a rehabilatated animal. Yellow tags mean that the sea lion is from San Miguel Island, which is off the Southern California coast near Santa Barbara. 

While the months of May and June are breeding season, the breeding normally takes place in Southern California. The female sea lions typically remain in the southern waters and give birth there. The males, however, tend to swim north once breeding season is over. Sometimes pretty far north, as indicated by the sight of any yellow-tagged sea lions in the San Francisco Bay. 
Sea Lions are considered “opportunistic feeders,” eating available prey rather than one species.
The average life span of a California Sea Lion is 20–25 years.