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Sea Otter in the kelp

Otter and pup
Otter on back
Sea Otter
Sea Otter
Young sea otter

Sea Otter

Enhydra lutris

The sea otter is a success story in progress on Vancouver Island. Totally extirpated through hunting by the early 1900s, a reintroduction of 89 individuals in 1969 has now grown to an estimated 3,000 individuals living from Cape Scott to Barkley Sound on the west coast of the island. They are the largest member of the weasel family (Mustelidae), but one of the smallest marine mammals, and they rely on their incredibly dense fur coat to trap air as insulation.


Description


The sea otter, weighing a maximum of 45 kg, is generally brown in colour, with a distinctive white face. While other marine mammals use a thick layer of blubber to keep warm, the sea otter uses its thick coat of fur, with a density approaching 165,000 hairs per square centimeter. The “scrubbing” behaviour noticeable while the otter is at the surface is actually the otter working a layer of air down to the roots of its coat, where it will stay, providing insulation from the cold water. The sea otter eats primarily bottom dwelling invertebrates, including sea urchins, clams, mussels, crabs, and will occasionally include easily caught fish. They are one of the only tool-using mammals, and will often be seen smashing open shells with rocks while floating on their backs.


Vancouver Island Range


The sea otter is distributed exclusively on the west coast of the island, ranging from Cape Scott in the north, to Barkley Sound in the south (though southward expansion is likely occurring). The restricted range is a result of the single introduction back onto Vancouver Island. In 1969, eighty-nine individuals from Alaska were released into the Bunsby Island Group about 25 km north of Kyuquot Sound, and they have been colonizing up and down the coast since. It is estimated that over 3,000 individuals now exist on the coast of Vancouver Island.

Because sea otters are socially living animals, there is not an even distribution of the animals throughout their range, and they tend to cluster where the best habitat exists. Sheltered kelp beds are their favourite habitat, and Nuchatlitz Inlet (near Nootka Island) is generally considered to be the most populated stretch of water.


Major Threats


Since they live in such a remote region of the island, habitat loss is not currently a large risk to these animals; the general consensus is that oil and fuel spills continue to be the major threat. It takes a very small amount of oil in the vicinity of a sea otter to result in a breakdown of the natural oil in the fur of the animals, and a loss of almost all insulating properties. Hypothermia and death follow very shortly after exposure to oil if not treated or rescued. This threat was realized following the famous Exxon Valdez spill in Alaska, which immediately killed over 1,000 otters, and removed hundreds of kilometers of habitat from their potential range. This remains a strong argument against the development of offshore oil drilling sites on BC’s coast.

Traditionally, hunting had been the major threat, but following their worldwide protection in 1911, this rapidly fell off. Poaching is certainly still a problem, but it is not prevalent enough to pose a major threat to the animals on Vancouver Island.

Sea otters are listed as endangered, and conservation, restoration, and reintroduction efforts are underway, attempting to restore them to somewhat historical levels.


Why they are Important on Vancouver Island


The sea otter is a keystone species on our coast. That is, it exerts an effect on its community far greater in proportion to the actual numbers of otters living in the community. Its regulation of the sea urchin population is the sole reason the urchins do not decimate the kelp forests. When the otters were hunted to near extinction, the kelp forests, and the vast majority of the life living in them, vanished. Now that the sea otters have been reintroduced, the urchin population is once again regulated, and the kelp forests (the most productive ecosystem in the world) are once again taking hold on Vancouver Island’s west coast.

 

Web site ©: The Institute for Coastal and Oceans Research (ICOR) at the University of Victoria, British Columbia Canada.