Small pox depopulated not only native Americans but Hawaians also. Measles nailed many as well.
Europeans had developed a "relative" immunity to these diseases due to natural selection in an urban environment. The native tribes were relatively isolated and were in essence immunological virgins.
You are correct.
But my comment was reflecting new research that suggests that the populations recorded by the earliest settlers were already significantly reduced by diseases spreading ahead of those settlers.
The population of California has often been placed at about 310,000 or so in 1769, the year the Spanish first settled at San Diego and pushed on to Monterey and San Francisco Bay.
But it is now being realized that earlier visits, from the early explorers such as Cabrillo and others, may have reduced the population significantly before 1769.
Here is a link to a good article (pdf format):
thanks for the link