Dive Dry with Dr. Bill

029: California Sea Lion

Catalina has been the home of many outstanding divers... after consulting other local divers, I decided the list was too long to print here. Despite my own years of experience, I couldn't hold a candle to them (it would go out underwater anyway). However none of these fine divers could out-dive the subject of this week's article, the California sea lion.

I rarely encounter sea lions in the Casino Dive Park, but was able to dive with them three times during my first stint on the Lindblad Expeditions ship MV Sea Bird. Los Islotes, a small group of exposed rocks just north of Isla Partida near La Paz, is home to a fair colony of these critters and they are none too shy with divers and snorkelers!

On my first dive at this site, a juvenile tried to rip the snorkle off my mask. I grabbed it and put it under my wetsuit for safekeeping. Teams of them bit my Zodiac's anchor chain and line, and attempted to relocate the anchor itself. On later dives these playful youngsters tried (or succeeded) to tear my buoyancy compensator off; loosen my fin straps; bite my fins; nip my shoulders, arms and legs; and even swallow the camera lens! I quickly adapted to this routine so I could continue to film the other marine life. Three of the ship's passengers were not so lucky... bites broke the skin, although each laughed over the experience and submitted to antibiotics.

For many of us, our first encounter with a sea lion was with the trained individuals in the circuses and zoos of our youth. There was a small industry in California that captured the young and females for this market. Some former captors, like Peter Howorth in Santa Barbara, later created centers to treat marine mammals when they are sick or injured.

Unlike the harbor seals also found here, sea lions are eared seals with obvious external flaps on their heads. They are also better adapted to walk on land than their distant relatives. Sea lions are more social than harbor seals with frequent communication through barking, "kisses" and body contact. While harbor seals give birth to their young here on Catalina, the California sea lions go to other islands during early summer to pup and mate. There are no rookeries on our island. The nearest ones are on San Clemente, San Nicolas and Santa Barbara Islands.

Males establish territories at the rookeries, often using ritualized displays and threats against, or actually fighting, other males to defend their turf. It is reported that they do not feed during this period. Males maintain their territories when the females arrive and pup, but do not gather harems and mate until pupping is completed. Females are free to move between harems as it is the territory itself that is defended by the male.

California sea lions are not restricted to the Californias. They are found from British Columbia south to the tip of Baja into the Gulf of California, off the Galapagos Islands and another population, possibly now extinct, lived in the Sea of Japan.

California sea lions have not always been the dominant species in our region. Until the late 1930's the much larger Steller sea lion was more abundant here and excluded the smaller California sea lions. Looking at the historic pictures of Old Ben, Avalon's "resident" sea lion, it appears to be the larger Steller species. Over time the Steller sea lion moved further north and the California sea lion population expanded into our region, and has grown larger over the years.

California sea lions feed on a wide variety of marine invertebrates and fishes, preferring open water species. Early food studies indicate they prefer squid, but will eat fish, octopus and even abalone when squid are unavailable. Schooling fish like anchovies, mackerel, flying fish and herring are a veritable supermarket for a sea lion.

Over the years there has been much debate over the impact of sea lions on regional fisheries. Certainly these marine mammals will opportunistically take fish off fishermen's lines and out of their nets. Since sea lions of one form or another have been here longer than humans, they may see things from a different perspective believing we are the ones stealing their fish! More than thirty years ago I photographed a group of adult sea lions shot at "Seal" Rocks, their bodies still dripping blood on the rocks. As of 1972 this and other species are fully protected under the federal Marine Mammal Protection Act.

For years I have unsuccessfully sought the ideal dive buddy... incredibly intelligent, beautiful, a fantastic diver with an intense love of the underwater world, wealthy (to fund a starving scientist's research and dive travel), and able to tolerate my cooking. Given the sea lion's abilities, perhaps I should look beyond my own species!

© 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: California sea lions at Los Islotes, Gulf of California, Mexico: juvenile with starfish;
juvenile about to bite camera lens; mature bull patroling; imcertain juvenile on bottom

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