Although sea lions are good swimmers, they find it much easier to capture more sluggish victims than game fish. Precautions are taken at Sea Lion Caves to prevent this from happening. They are slate gray in color for about six months, turn dark brown until approximately two years of age, and they begin to assume the lighter tan color of the adult. They remain with their mothers well over a year and grow rapidly, averaging about six feet long at the end of their first year. The pups continue to grow, perhaps all of their lives, but the growth rate decreases each year.
Mature cows are identifiable by their size and long slender shape.
They average about eight or nine feet in length and weigh from six to seven hundred pounds. The bulls are much larger and have massive shoulders. They average twelve feet in length and weigh around 1500 pounds. Many extremely large bulls have been known to weigh well over a ton. The average life span of these animals is believed to be about 20 years.