Video: Sea otters surface from brink of extinction
After being nearly wiped out a century ago, the sea otter population in Canada is booming. But not everyone is glad to welcome them back
IT’S shortly after dawn on Canada’s west coast. We’re standing on a rocky islet, and below us are the animals we have come to watch: about 15 sea otters are grooming, snacking and snoozing in the ocean. Then four fishing skiffs zoom by and the otters scatter.
I’m here with marine ecologist Erin Rechsteiner, who has been watching sea otters at this particular spot since they first arrived in autumn 2013. The raft of males, numbering up to 130 animals in winter and spring, is a sea otter vanguard.
Advertisement
“We’re right on the edge of their range, for the moment,” Rechsteiner says. When the males turned up, they feasted on sea urchins. “We’re watching them shift to different foods now that they’ve been here for a few months. It would be like if you arrive in town where no one else is around and you raid the candy store, and once the candy is hard to find you raid the vegetable garden next.”
Once sea urchins become less common, though, the whole nature of the ecosystem changes. The sea otter’s return to British Columbia’s coast is a blitzkrieg, a lightning transformation of an ecosystem.
It is estimated that at least 300,000 sea otters roamed the coastline of the North Pacific, from Japan to California, when hunting began in earnest in the 1740s. Their luxurious fur was so sought after that only a few thousand remained by 1911, when .
Once protected, most of the surviving pockets of sea otters scattered around the Pacific bounced back remarkably rapidly, although their range remained small. In the 1960s, a few hundred sea otters were relocated to some of the places where they had been wiped out.
Today most populations are stable or growing, although there are a few exceptions. The recovery of the famous California population has been very slow and now seems to have stalled just short of 3000 animals. And in south-west Alaska, a thriving population was suddenly decimated in the 1990s, with as many as 65,000 being lost. It’s not clear why: one idea is that declining seal numbers caused orcas to start feeding on the otters instead.
Here in British Columbia, 89 sea otters were reintroduced to Vancouver Island’s west coast in the 1960s. The population now numbers about 5000, and the animals are advancing north up the coast. Rechsteiner and her colleagues at the Hakai Institute on Calvert Island are studying their advance.
Canadian sea otters are back, with dramatic results (Image: All Canada Photos/Alamy)
Groups of otters are known as rafts because of their habit of floating together on the sea surface between dives, often holding hands to keep from drifting apart. Male rafts, like the one Rechsteiner watches, are the first to arrive in an otter-free zone and indulge in the stellar buffet on the ocean floor.
Obsessive groomers
The animals have a voracious appetite: while we eat food equivalent to around 2 per cent of our body weight each day, an otter consumes about 30 per cent. They have to eat so much to stay warm in these cold waters, especially as, unusually for a sea mammal, they have no blubber. Instead they have the fur that was so nearly their downfall, and to keep it warm and dry they have to groom it obsessively. As we see over the course of the day, eating and grooming take up much of their time.
Their favourite food is sea urchins – some of which may – and the result of their feasting is striking. Around the rocky islet, the ocean surface has been transformed, with bulbous kelp bobbing in the water where there was none a few months ago. With the remaining kelp-grazing sea urchins hiding in rock crevices to avoid otters, the ecosystem reaches a tipping point and the kelp forests return. “The urchins become lazy, scaredy-pants drift feeders and eat dead kelp as it passes them by,” Rechsteiner says. “They no longer graze on kelp in the open or get out to mow down the kelp forest because if they’re out in the open, an otter eats them.”
“The sea urchins become scaredy-pants. They no longer mow down the kelp”
Once they have devoured all the urchins, the males turn to clams, crabs, abalone and other shellfish. Rechsteiner suspects that by the time this article comes out, the raft will have moved on in search of another habitat rich in sea urchins. The pioneering males will be replaced by females, pups and territorial males waiting to mate. These resident otters will keep the urchins in hiding and the kelp thriving.
That’s good news. “I always tell people they should appreciate kelp because it does a lot of amazing things,” says Jane Watson of Vancouver Island University, who has been studying the otter-kelp ecosystem for over 20 years. “Perhaps the most important thing it does is increase the productivity of near-shore ecosystems.”
Kelp forests harbour a much wider range of species than a sea floor grazed bare by urchins, and increase overall fish numbers. The forests also form natural breakwaters, protecting coasts from erosion. And it’s not just local people who benefit – the kelp forests even help remove significant quantities of carbon dioxide from the atmosphere.
But not everyone is thrilled about the otters’ return. Coastal residents who harvest shellfish, including many members of First Nation tribes, compete directly with sea otters. In some waters, people already harass and sometimes illegally shoot the animals. So conservationists have been meeting with local leaders to try to head off a looming conflict.
Guujaaw, a member of the Haida Nation, says it is necessary to recognise that indigenous people are a natural part of the ecology. “Otters are also natural in the ecosystem, even a benefit to marine plants, and ultimately to ourselves,” Guujaaw says. “At the same time, populations out of control could upset the balance and deprive people of food sources.”
In practice, this may mean allowing limited hunting in some areas. After all, the evidence suggests that prior to the arrival of Europeans a balance existed, with coastal communities hunting sea otters for thousands of years without wiping them out. But finding a new balance as the otters reclaim their lost territory won’t be easy, says Watson. “It’s going to take a tremendous amount of cooperation, collaboration and interactions between different groups of people.”
Romeos or rapists?
Few animals look as as a sea otter. But their adorable appearance belies a side to them that in the human world would be considered deviant – some males will mate with anything vaguely otter-like, including dogs and baby seals. On one occasion a sea otter was recorded copulating with a cormorant.
The victims often drown in the process or suffer serious injuries. The behaviour may be a result of the otters’ social structure. “Not many of the males get to have their own territory,” says Erin Rechsteiner of the Hakai Institute in British Columbia, Canada. “There can be many years of a male otter being sexually active but having no access to females.”
Even adult female otters can be seriously injured during mating, but this is not particularly unusual in the animal world. In the past year, though, Rechsteiner has seen no copulations with other species and three male-female pairs mating. “It was,” she says, turning the sex-deviant meme on its head, “quite romantic.”
This article appeared in print under the headline “The comeback cubs”
