Seals, sea lions, and fur seals are also known as pinnipeds. These mammals lead a partly terrestrial and partly a marine existence. Their streamlined bodies, specialized flippers and insulating layer of blubber allow them to travel and forage at sea with ease. However, unlike dolphins, porpoises and whales, pinnipeds require land to bear and suckle their young and to rest.

Five species of pinnipeds, representing two families, occur in the Monterey Bay. The family Phocidae (true seals) includes the northern elephant seal and harbour seal, and the family Otariidae (eared seals) includes the California and Steller sea lions and the northern fur seal.

True seals are characterized by the absence of external ear flaps and by their short, fur-covered flippers. The rear flippers cannot be rotated forward, so they move in a caterpillar-like fashion when on land. In water, seals swim by alternating side-to-side strokes of their rear flippers, while the front flippers aid in steering.

Eared seals, on the other hand, have small external ear flaps and large hairless flippers. The rear flippers can be rotated under the body, which allows these animals to amble over land using both the front and rear flippers. While swimming, they use their front flippers like wings to propel and steer themselves.



True seals (Family Phocidae)

Pacific Harbor Seal (Phoca vitulina richardii)

Maximum Length: Both sexes measure 5-6 ft (1.7-1.9 m)
Weight: Both sexes weigh up to 300 lbs (150 kg)
Range: Baja California Sur, Mexico to the Gulf of Alaska
Population: Approximately 30,000 in California

Northern Elephant Seal (Mirounga angustirostris)
Maximum Length: Males measure 13 ft (4 m) and females measure 10 ft (3 m)
Weight: Males weigh 4,500 lbs (2,000 kg) and females weigh 1,500 lbs (600 kg)
Range: Baja California, Mexico to the Gulf of Alaska and the Aleutian Islands
Population: Approximately 101,000 in California



Sea Lions (Family Otariidae)

California Sea Lion (Zalophus californianus)
Maximum Length: Males measure 7 ft (2.1 m) and females measure 6 ft (1.8 m)
Weight: Males weigh between 850-1,000 lbs (390-454 kg) and females weigh 220 lbs (110 kg)
Range: Southern Mexico to southwestern Canada
Population: Approximately 244,000 individuals

Northern or Stellar Sea Lion (Eumatopias jubatus)
Maximum Length: Males measure 11 ft (3.25 m) and females measure 9 ft (2.9 m)
Weight: Males weigh 2,500 lbs (1120 kg) and females weigh 1,000 lbs (350 kg)
Range: Throughout the North Pacific Rim from Japan to central California.
Population: Approximately 6,555 individuals living in California



Fur Seals (Family Otariidae)

Northern Fur Seal (Callorhinus ursinus)
Maximum Length: Males measure 7 ft (2.1 m) and females measure 4.5 ft (1.4 m)
Weight: Males weigh between 385-605 lbs (175-275 kg) and females weigh between 66-110 lbs (30-50 kg)
Range: Throughout the North Pacific rim from Japan to the Channel Islands of California
Population: Approximately 941,756 individuals

References:

Caretta, J., J. Barlow, K. A. Forney, M. M. Muto, J. Barlow, J. Baker, and M. Lowry. 2004.
U. S. Pacific Marine Mammal Stock Assessments: 2003. United States Department of Commerce, National Oceanic Atmospheric Administration Technical Memorandum
NMFS-SWFSC-358.

Reeves, R. R., B. S. Stewart, and S. Leatherwood. 1992. The Sierra Club Handbook of Seals and Sirenians. Sierra Club Book, San Francisco, California, USA.