Dive Dry with Dr. Bill

020: Harbor Seal

Our local waters are beginning to cool off as winter approaches. I've found recent water temperatures fairly consistent (59-61 degrees F) from 90 feet to the surface. Colder water fish like cabezon are appearing in the shallower waters. "Warm-blooded" species (like me) are wishing we had more natural "insulation," thinking about shedding the 3mm wetsuit in favor of something a bit warmer, or heading off to the tropics!

Several species found in our waters adjust their internal "wetsuit" or blubber to meet the changing conditions! Last February while underwater off the Casino, I was briefly joined by a buddy who was much happier than I was to be in the cold water. The harbor seal is a marine mammal seen occasionally in our Dive Park, but more frequently along the island's isolated windward coast. However while kayaking this summer, I spotted seven harbor seals hauled out on rocks between Gallagher's and Toyon Bay on the leeward side. Having lived at Toyon from 1969 to 1979, I don't remember seeing so many in one small human-populated area. The harbor seal is not unique to our area. It is also found from the Arctic south along the Pacific Coast down into Baja California, as well as south along the Atlantic coast to the Carolinas.

This small true seal reaches lengths of about five feet and may weigh up to 255 pounds. It is variable in color and may be a uniform silver-gray or brownish in color, but often is gray with brown spots or vice-versa. Fortunately for it, the coat was not considered valuable like that of the unrelated sea otter which was hunted to local extinction in the early 1800's. The more social and common California sea lion, and the larger northern elephant seal, lack these spots. Unlike the sea lion, harbor seals do not have external ear flaps. They are also more clumsy on land because harbor seals cannot rotate their rear flippers like sea lions (the "seals" of the circus).

Harbor seals spend most of their time in coastal regions, often hauled out on shore or on rocks at low tide. Because they give birth on the island, unlike sea lions, they are resident here year-round. Harbor seals form small social groups. Males and females are similar in size and appearance. Male harbor seals do not defend harems like sea lions. Females are sexually mature at about two years old. The pups are born in the early summer after a nine month gestation period. They lose their whitish juvenile fur by the end of the first year.

Back in 1971 while diving at Long Point with my former student and close friend Chris Conrad, I had an experience I will never forget. A young harbor seal swam up to us without the least bit of shyness. It then dove to the bottom and somehow managed to pick up a sea cucumber in its front flippers which amazed me. I was even more astounded when it brought the sea cucumber up to us and pushed it towards us. Chris, the harbor seal and I ended up playing "catch" with the sea cucumber for a few minutes. While diving at the Casino nearly 30 years later, Chris and I recounted that story to the amusement (and disbelief!) of our other buddies that day.

Harbor seals feed on fish, shellfish and squid taken while underwater. At night divers often see them picking off blacksmith and other fish that get "caught" in the beam of the dive lights. In addition to their natural insulation, there is another characteristic I envy. Harbor seals may stay underwater for 20 minutes at a time. I wonder how long my 120 cu. ft. tank would last if I had their respiratory efficiency! As for buddies, I still prefer the human kind since they rarely eat the fish I'm trying to videotape!

© 2003 Dr. Bill Bushing. Watch the "Dive Dry with Dr. Bill" underwater videos on Catalina Cable TV channel 49, 10:00 AM and 5:00 PM weekdays.

Image caption: Individual harbor seal diving with me in Casino Dive Park

This document maintained by Dr. Bill Bushing.
Material © 2003 Star Thrower Educational Multimedia