Research team studies health, foraging behaviour of sea otters

Underwater vehicles used to capture the mammals on Vancouver Island

By Larry Pynn, Vancouver Sun, June 24, 2010 – p. A4

A Canada-U. S. study into the health and foraging behaviour of sea otters between Alaska and California has employed small underwater vehicles to capture the marine mammals on the west coast of Vancouver Island.

An international team of 10 researchers has just returned from three weeks in the Clayoquot Sound and Esperanza Inlet area during which 46 sea otters were captured and their flippers tagged.

Researchers also measured and weighed the otters—the largest male tipping the scales at 40 kilograms—and took samples of blood, fur, skin, even whiskers before releasing them. Results of the continuing study will provide information not just on sea otter populations along the Pacific coast, but on the health of the coastal ecosystems upon which they depend.

Linda Nichol, a federal marine mammal research biologist, explained that specially trained researchers with the U.S. Geological Survey operated small, battery-operated, propeller-driven vehicles and wore rebreather units that allowed them to operate under water without generating bubbles that would scare away the otters.

Traps mounted on the vehicles scooped up the otters as they rested together on the surface. “They’re guided by shore spotters who radio to them,” she said in an interview from the Pacific Biological Station in Nanaimo. “They come up, pull the draw string, and hope they have an otter in the trap. It’s quite slick, actually.”

Modified gillnets were also used to trap otters for the research, which will continue next year.

Unlike other marine mammals, otters bring their prey to the surface to be consumed and identified by researchers, she continued. “It’s a matter of a very good spotting scope and being patient.”

Diet tends to be more varied where otters are well established; sea urchins, for example, may give way to mussels. Unlike river otters, sea otters in B.C. do not eat fish.

Researchers handling sea otters must be careful to avoid their powerful teeth. “It would be quite serious,” Nichol confirmed. “They’d go right through your hand if they bit you. They’re incredibly agile. They can almost literally turn around in their skin.”

Sea otters were wiped out in B.C. during the fur trade beginning in the mid-1700s. Between 1969 and 1972, 89 animals were reintroduced from Alaska to Checleset Bay on the west coast of Vancouver Island.

Federally downlisted to special concern from threatened in 2007, sea otters numbered an estimated 4,700 in 2008, up from almost 3,200 in 2004. Those numbers are well below historic figures estimated at up to 70,000 or more.

Otters continue to expand their range in B.C. and are now established as far south as Clayoquot Sound, where they are frequently spotted during commercial whale-watch trips. Males explore new territory first, followed by the females.

The Nuu-chah-nulth Tribal Council has indicated it would like to conduct a kill of sea otters for traditional ceremonial purposes, but no such hunt is imminent.