Pinnipedia, from the Latin pinna (fin) and ped- (foot), is a taxonomic clade of semiaquatic mammals that includes seals, sea lions and walruses. Pinnipeds are close relatives of modern bears, and part of the order Carnivora. There are four species of pinnepeds in the northeast Pacific; two seals and two sea lions.
Although very similar in appearance, seals and sea lions differ on a few key features. Sea lions have external earflaps and long, furless front flippers. They can raise their heads and shoulders and rotate their hind flippers underneath their bodies, allowing them to walk and gallop on land. Seals have no external earflaps and short, fur-covered front flippers. They cannot raise their heads and shoulders very well, and are incapable of rotating their back flippers underneath themselves. This makes them very awkward on land, where they must undulate their bodies in an inchworm-like fashion to travel.
Ocean Networks Canada has recorded the following Pinniped species:
- California Sea Lion
Steller Sea Lion
The Steller sea lion is the largest species of sea lion. Males are larger than females, and average 3 m long and 544 kg. Female Steller sea lions are 2.5 m long and weigh 263 kg on average. They can live for up to 30 years. Steller sea lions inhabit coastal areas all around the northern Pacific Ocean. Their range extends from northern California to northern Honshu, Japan, including the Bering Strait. Approximately 70% of the Steller sea lion population is in Alaska. Steller sea lions are not migratory, but they do move seasonally between feeding and resting areas. The deepest recorded dive for a Steller sea lion was 424 m. Their diet is varied, and can include Pacific herring, salmon, cod, pollock, rockfishes, some squid species and octopi. They often have stones in their stomachs, which may help grind their food, or perhaps serve as ballast while diving or prevent hunger pangs while they fast on shore.
Steller sea lions are polygynous, meaning that one male will mate with many females during a mating season, while females will typically mate with only one male. Males arrive at rookeries in May. Dominant males (usually 9 years of age or older) establish territories that they will maintain for about 40 days without eating. Females arrive and give birth to the pups of the previous year from Mid-May to mid-July, and mate soon after with the male controlling the territory that they have settled on.
The Steller sea lion population has declined more than 75% since 1980 for unknown reasons. Possible reasons for this decline include disease, parasites, environmental factors, changes in prey quality or abundance, predation by Bigg’s orcas and competition with other animal species for food (including competition with human fisheries). Their predators include Bigg’s orcas, sharks and humans. Threats include ship strikes, pollution, habitat degradation, offshore oil and gas exploration, illegal shooting/hunting, bycatch in fisheries and entanglement in fishing gear.
California sea lions are perhaps the most recognizable of all sea lions, because they are common attractions at marine parks and aquaria. They are very playful, and have been observed surfing breaking waves in some places. Curious, intelligent and easily trainable, these animals have been used by the US Navy for equipment recovery, harbour and ship protection, and mine detection and clearance. They have very sensitive, directional hearing underwater and exceptional eyesight in low light. The longest dive on record by a California sea lion lasted 12 minutes, and the deepest dive was to 536 m.They eat a variety of marine species, including squid, mackerel, anchovies, sardines and rockfish. Females grow to an average of 2 m and 140 kg, and males grow to 2.25 m and 315 kg. They can live for 20 to 30 years.
California Sea Lion
California sea lions inhabit shallow, estuarine and coastal waters in the northeastern Pacific Ocean, and range from Central Mexico to Northern British Columbia. They are very gregarious, with some groups on shore numbering in the hundreds. California sea lions are polygynous. Males maintain territories during the breeding season that may include up to 14 females. They defend their territories from other males with aggressive visual displays and vocalizations. Their breeding season is from May to August, and their pups are born between May and July the following year.
Orcas, sharks and humans are predators of the California sea lion. Threats to California sea lions include entanglement in fishing gear, bycatch in fisheries, pollution, and shooting by fishermen.
Harbour seals can be found in coastal waters, river systems and estuaries in the temperate northern hemisphere. They grow to a maximum of 1.9 m long and 120 kg. Harbour seals can be a variety of colours, from black to brown to grey, and are usually speckled. They were extensively hunted for their pelts, but have since recovered. There are several subspecies of harbour seal. The Pacific harbour seal is one such subspecies, and can be found along the coastline of the northeastern Pacific Ocean from California to Alaska. They eat 3-5 kg of food a day. Their diet is comprised primarily of shallow water fish species, such as greenlings, rockfish, perch, smelt, herring and some flatfishes, although they also eat hake and seasonal salmonids in the Strait of Georgia between Vancouver Island and the mainland of British Columbia. They mate in the late spring and summer months, and give birth between June and September on beaches and tidal reefs.
Harbour seals have acute eyesight and hearing. They also have whiskers that are very sensitive to pressure changes in the water and can be extended forward to inspect things in low light conditions. They do not appear to be dependent on their eyesight, as blind harbour seals can thrive in the wild.
Harbour seals can dive down to 300 m and hold their breath for up to 25 minutes. They have a dive reflex, which reduces their heart rate by about 90% and reduces their circulation (except to the heart and brain) while their face is submerged. Their nervous system automatically prevents them from attempting to breathe at inappropriate times, allowing them to sleep underwater. While sleeping, they will surface to breathe subconsciously.
Harbour seals are an important food source for Bigg’s orcas. Other predators of harbour seals include sharks and humans. Harbour seals are still hunted by some native groups, and may be shot by fishermen. Threats to the harbour seal include pollution, overfishing, entanglement in fishing gear and debris, disease and parasites.
Northern Elephant Seal
The elephant seal is the longest non-cetacean mammal. Male southern elephant seals can grow up to 5.8 m long; longer than their northern elephant seal counterparts, which grow up to 4.9 m long and 2455 kg. Female northern and southern elephant seals are of comparable size, growing up to about 3 m long and 640 kg. They can live for about 20 years. Northern elephant seals can be found along the Pacific coast of Mexico and North America. Their most northerly breeding location is at Race Rocks, off of Victoria, British Columbia in Canada, however non-breeding individuals can be found up to Alaska. They spend much of their lives in the water and typically feed in waters deeper than 200 m. They come ashore for a few months of the year, during which they undergo a catastrophic molt, birth the previous year’s pups, and breed.
Female elephant seals typically feed in offshore waters, and males along the continental shelf. Their average dives are to depths between 300 and 600 m. The deepest dive on record by an elephant seal was to 2388 m. They can hold their breath for more than 100 minutes. They eat squid, octopi, large fish, small sharks, skates, rays and eels. A female elephant seal was spotted eating a hagfish from the sea floor at Ocean Netwokrs Canada's Barkley Canyon Pod 4 camera (depth: 894 m), but it is not known how significant hagfish are to their diet.
Elephant seals are polygynous, and famous for the violent battles between males to establish dominance during the mating season. Battles are usually not to the death, but they do result in significant injuries and bloodshed. Few male elephant seals earn the right to a harem, and most will only get to mate if they succeed in mounting a female in another male’s harem without being noticed. The highest ranking males may have harems of 30 to 100 females, and impregnate up to 50 females in a single breeding season. But defending their harems presents a unique challenge. Elephant seals get fresh water from their food instead of drinking, and must remain on the beach to defend their harem. Their elongated, elephant-like noses help them reabsorb moisture from their exhalations, allowing them to stay ashore longer without getting dehydrated.
Predators of the elephant seal include Bigg’s orcas, sharks and humans. They were hunted to near-extinction by humans in the 19th century, but have since recovered. Threats to the elephant seal include entanglement in marine debris, fishery interactions and boat collisions.