Introduction

How do you know it’s November in Cowichan Bay? You can hear and smell the male Steller sea lions (Eumetopias jubatus). These big boys visit Cowichan Bay every November to feast on the salmon returning to the Cowichan and Koksilah Rivers on their way to the spawning grounds. Weighing up to 800 kg, male Steller sea lions are so big that one or two of them can sink a small sailboat, as some locals have recently learned the hard way. Steller sea lions are quite gregarious and communicate with loud roars and deep growls. These sea lions are shallow divers and can hold their breath for approximately 16 minutes underwater. California sea lions (Zalophus californianus) also visit Cowichan Bay to feast on salmon in November. California sea lions are smaller and darker in colour compared to Steller sea lions, and mature males have a bump on their forehead called a sagittal crest. Check back on our website in the fall for more videos and sound clips of sea lions!

However, what’s good news for seals and sea lions is not such good news for the rivers’ salmon runs as increasing drought conditions in our watersheds can leave large numbers of salmon waiting in the estuary for increased river flows in order to migrate up-stream, and getting eaten by seals and sea lions as they wait.

Look

Steller sea lions gather at the breakwater in Cowichan Bay every November. Male Steller sea lions can reach a height of 3 meters, and can weigh up to 800 kg. The locals affectionately call the annual gathering at the marina, a “bachelor party.” Image Credit: Eric Marshall

What brings the sea lions to the estuary? Here we see a Steller sea lion that has just caught a fish, likely Chum salmon. Sea lions feast on salmon returning to the Cowichan and Koksilah Rivers to spawn and complete their life cycle. In British Columbia, Steller sea lions eat mainly schooling fish such as salmon, herring and sardines. Image Credit: Eric Marshall

Steller and California sea lions rest on the dock at Cowichan Bay. California sea lions are smaller and darker in colour compared to Steller sea lions. Sea lions are social animals that can often be found resting together (and on top of each other) on docks. They also mingle with each other in the water and can create a floating raft of sea lions! Image Credit: Eric Marshall

Steller sea lions have a distinctive, low frequency roar. Male sea lions seen here use sound to communicate with each other or to defend their territory. At rookeries, females use sound to find their pups. In fact, British Columbia is home to the world’s largest rookery on Triangle Island off the northern coast of Vancouver Island. Image Credit: Eric Marshall

Sea lions sometimes rest on boats in the marina. Unfortunately, they leave smelly feces, and their heavy weight can lead to boat damage. To help reduce the population of sea lions, a First Nations group applied for a commercial license to harvest sea lions in Cowichan Bay. The permission was not granted by the Department of Fisheries and Oceans, and the controversy continues on how humans can coexist with wildlife. Image Credit: Eric Marshall

Listen

Caption: Listen to California sea lions barking underwater. The sound was recorded using a hydrophone (an underwater microphone) near Denman Island during the wee hours (~2am) of March 11, 2020.

Audio Credit: Philina English, Fisheries and Oceans Canada

Resources

Read Times Colonist’s article on sea lions throwing a bachelor party at Cowichan Bay.
Read more facts about Steller and California sea lions from the University of British Columbia’s Marine Mammal Research Unit.
Watch videos of sea lions at Race Rocks Ecological Reserve on the southern tip of Vancouver Island.
Watch a video of sea lion research using GoPros from the Vancouver Aquarium.
Watch Marine Detective’s video of Steller and California sea lions barking underwater.
Read a Fisheries and Oceans Canada report on the status of Steller sea lions in Canada.
Read the Globe and Mail’s article about the proposed BC seal and sea lion hunt.