The most common species of pinnipeds found in the Salish Sea are the harbor seal, California sea lion and the Steller sea lion. Here we are going to highlight these ‘regulars’. We will start with the smallest (and most common) and move our way up to the largest (and less common).
The harbor seal is the second smallest of the true seals (the phocids) and the most common marine mammal along both the east and west coasts of the United States, and the most common marine mammal here in the Salish Sea. They were once ‘wanted’, with a State financed bounty on their heads in WA and OR because they competed with fishermen. Luckily this ended in 1960, and since then they have made a complete recovery in this area and have a very healthy population.
Their small size and spotting pattern makes them easy to distinguish from the other pinniped species in the Salish Sea that are large and only different shades of brown. Those spotting patterns can vary from light with dark spots, to dark with light spots and everywhere in between. The patterns also unique to each individual, so researchers (like ourselves) can non-invasively track them over time using photo-identification to learn about aspects of their lives including social behaviors, movement patterns and habitat use.
They are not picky eaters, as their prey items include over 60 species of crustaceans, cephalopods, and fish. Well adapted for diving, perhaps the coolest of their many adaptations is that they can exchange 90% of the air in their lungs (we can only do about 20%), and that they can slow their heart rate (called bradycardia) from 55-120 beats per minute to 4-15 beats per minute as they prepare to dive.
They spend about half their life in the water and half on land, at various haul-out locations where they tend to stay close to. These haul-outs are important for resting, thermoregulation (catching some rays!), molting (they lose and regain their coat each year), nursing, giving birth and protection from predators. These areas are crucial for them, and if disturbed can have negative effects on the individual, and population as a whole. It is important to remember to appreciate them from a distance! There are a lot of cool things about the harbor seal, but I will leave you with this – they can sleep underwater and hold their breath for 30 minutes!
California Sea Lion
California sea lions (Zalophus californianus) are native to the West Coast of North America and are one of our most well-known pinnipeds. CA sea lions live in coastal waters on beaches, buoys, docks and jetties – you might have heard them, they’re very noisy! They are also highly intelligent and easily trained, thus are frequently star attractions at aquariums and zoos.
The male CA sea lions can weigh up to 700 lbs and reach 7.5 feet in length. The males develop a pronounced sagittal crest – basically a big bump on their forehead – that develops as they reach sexual maturity. A dark brown to light tan, CA sea lions show sexual dimorphism, i.e. males and females are strikingly different from each other. The females are about half the weight of the males, weighing around 250 lbs, and grow to about 6 feet in length. There are also differences in how they vocalize: males bark (very loudly!); females, although they will also bark with other adults, have unique vocalizations they use with their pups to enable them to identify one another on beaches crowded with other sea lions. Cool huh?!
Pups will feed from their mothers for the first 2-5 days of their life. After that, the mothers must go back to sea to forage for themselves, and will leave their pups on land for several days at a time. It can take up to 1 year for CA sea lion pups to become fully weaned, so it is super important to leave any young sea lions on the beach alone and do not approach them! If they appear to be in distress, you can call your local stranding network branch, but otherwise they are likely just waiting for mom to return with some food!
Steller Sea Lion
The Steller sea lion, named after Georg Wilhelm Steller who described the species, is the largest of the eared seals and only inferior in size to the elephant seals and walrus within the pinnipeds. Commonly found in Washington waters, Stellers range all the way north to the Gulf of Alaska to central California in the south. With males weighing up to 2500 pounds, this species exhibits multiple traits evident of sexual dimorphism. The smaller females (up to 750 pounds) lack the distinctive wide chests and broader and higher foreheads, as we well as the distinctive “mane” around the neck area seen in the males. The males generally breed in territorial harems within rookeries, controlling a geographically defined territory and mating with multiple mature females that come to that territory. The females will typically give birth soon after arrival to the rookery before quickly mating again, nursing their pups for a few weeks before they are large enough to forage on their own.
As opportunistic hunters, Steller sea lions feed on a variety of fish and cephalopods (squid and octopus). This sea lion is able to exhibit bradycardia (slowing of the heart rate) and narrowing of blood vessels to maximize oxygen efficiency while hunting underwater. However, this species faces many threats with the fishing industry, whether it be accidentally entangled in fishing gear or competition with fisherman that can lead to them to be killed. Recently, along with California sea lion, Steller sea lions have been entering the Columbia River to feed on sturgeon salmonids, competing with other fisherman and challenging the management of these sensitive fisheries stocks. Protected by the Marine Mammal Act, this poses a major problem to the protection of this species, with constant debates of if/how to remove the sea lion from the estuary.