In many ways, the natural history of coastal British Columbia is the history of sea otters. That’s one of the things Dr. Jane Watson hopes her research makes clear.
In 1850, there were probably few sea otters left on the B.C. coast compared to the 50,000 or so that had been here when the first European fur traders arrived—they had been hunted to local extinction in less than a century. Today, there are roughly 6,500 sea otters in B.C., a remarkable recovery that has also had some surprising consequences.
From flourishing to extinction to recovery, “The Sea Otter Story”—which Dr. Watson will present as part of Capilano University’s EarthWorks series—is one that has had a major effect on the environment, economics, and politics of the province.
The sea otter story
Local First Nations had harvested sea otters for thousands of years before Europeans arrived in B.C., but likely never in large enough quantities to deplete the population. When fur traders showed up, however, otter fur became known as “soft gold.”
“It’s a fur that is denser than any other animal fur on the face of the earth,” Dr. Watson says. “It’s soft, it’s a beautiful colour, and when the first Europeans arrived on the west coast of North America, the height of fashion in Imperial China was to trim robes with fur.”
By 1867, the fur seals and sea otters that first brought the Russians to Alaska had become rare. This lack of fur resources, in turn, contributed to Russia’s decision to sell Alaska to the United States. “Without sea otters and fur seals, Alaska probably would have been British, so part of Canada,” Dr. Watson says. “I always look at these animals and think they had a profound effect on geopolitics.”
While the fur trade was redrawing borders on land, it was having an even more significant effect on the coastal ecosystem in B.C.
Sea otters are unusual among marine mammals in that they don’t have a layer of blubber to keep them insulated in the water. Instead, they blow air into their dense fur. They use body heat to warm the trapped air and insulate themselves against the chilly north Pacific. To do this, says Dr. Watson, they require a metabolism that’s “running on overtime.”
A sea otter also has to eat 25 per cent of its body weight each day—which translates into about 7 kg of food for a male. Otters eat sea urchins and other marine invertebrates. Before the fur trade, their prodigious appetites likely had a limiting affect on these populations.
In particular, the removal of sea otters from the ecosystem led to an increase in the abundance of sea urchins, which graze on kelp. As sea urchin populations grew, grazing increased and kelp forests disappeared. In addition to a surge in sea urchins, species like geoducks, crabs, and sea cucumbers also increased, which contributed to the growth of valuable commercial shellfisheries. “They’re multimillion-dollar fisheries,” Dr. Watson says. “And they’re only possible, really, because a predator that used to control all those species disappeared.”
Sea otter recovery
Between 1969 and 1972, a total of 89 sea otters from Alaska were reintroduced to B.C. waters. Since then, their population has grown, and many of the effects of their removal are reversing. Ecologically important kelp forests are returning, but shellfish, valuable to First Nations as well as commercial and recreational harvesters, are declining.
According to Dr. Watson, the shellfishing industries that have grown up in the absence of sea otters are now finding it difficult to compete. Even harder hit by the return of sea otters are coastal First Nations, whose subsistence fisheries are not as mobile as commercial ones. “Commercial fishermen can just get a reallocation in another area on the coast where there aren’t sea otters,” she says. But for First Nations fisheries, “If that’s your territory, that’s your territory.
‘Everything is connected’
The study of the relationships between species in a given ecosystem is called “community ecology.” It’s something Dr. Watson has been studying since she came across the otter-urchin-kelp connection while working on a term paper as a third-year undergraduate at UBC.
Today, Dr. Watson shares her passion for the subject as a biology professor at Vancouver Island University. Her biggest takeaway from the sea otter story is a concept she attributes to the Nuu-chah-nulth First Nations: “everything is connected.”
“You poke at one part of an ecosystem and something will change elsewhere, and I don’t think we can always predict what that change is going to be,” Watson says. “As managers of resources, that’s the type of consideration that we have to always keep in mind: that these systems are always changing. Quite often, the things that we’re trying to manage evolved in a very different environment than the one we are currently managing them in.”
Submitted by Marketing & Communications