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British Columbia: Sea Otter Research Expedition |
| October 20, 2004 |
By Lance Barrett-Lennard Ph.D.
Senior Marine Mammal Scientist, Vancouver Aquarium Marine Science Centre
 | Scientists are researching the genetics and health of two sea otter populations off the coast of Vancouver Island.
Photo: Lance Barrett-Lennard |
If you don’t believe that sea otters were once common in BC, take a look at the names of some of the places along our coast. You’ll find Sea Otter Inlet, Sea Otter Islands, Sea Otter Rock and Sea Otter Cove – to name just a few.
When the first Europeans arrived on our coast, sea otters were common from California to the Aleutian Islands. Their superb fur sparked a lucrative hunting and trading industry in the 1700’s. By the late 1800’s, only a few tiny remnant populations remained – less than 2,000 individuals in total. A single sea otter shot in 1941 is thought to have been the last of British Columbia’s original population, although it is possible that a handful of survivors escaped notice somewhere along our long and complex coastline.
In 1969, Fisheries Department biologist Ian MacAskie spearheaded the reintroduction of sea otters to BC, transplanting 29 otters from the Aleutian Islands to the west side of Vancouver Island near Kyuquot. Over the next three years, 70 sea otters from Alaska’s Prince William Sound were released in the same area. The new arrivals flourished and the population has since expanded to at least 3,000 – an increase of over 11% per year. Their range has also expanded, and they can now be found from Tofino to Cape Scott.
In 1989, biologists from the Canadian Wildlife Service discovered a separate colony on the central coast of BC near remote Goose Island. The central coast colony has grown substantially since it was first sighted and now numbers about 300 individuals. It is not known whether it was started by animals from the transplants three decades ago or whether it was founded by survivors of the fur trade.
Dr. Jane Watson, a Malaspina University professor who has studied BC’s sea otters since the 1980’s, has documented dramatic changes that occur when they colonize a new area. According to Dr. Watson, they quickly eat their way through the largest sea urchins, snail-like shellfish and crabs before turning to a diet of clams. Grazing on kelp and other algae, sea urchins often create vast bare areas referred to as urchin barrens. By removing urchins, sea otters allow kelp forests to re-establish, providing habitat and rearing grounds for a host of fish and invertebrate species. As a result, their return to BC has profound consequences for entire marine ecosystems.
Studying Today's Sea Otters
For the past two Septembers, the Aquarium’s Veterinarian Dr. Dave Huff, Vice President of Operations Clint Wright and I have joined an expedition of scientists studying the genetics, health, and contaminant exposure of the central coast sea otter population. The team was led by Linda Nichol, a biologist with Fisheries and Oceans Canada, and included scientists from the Institute of Ocean Sciences, the US Geological Survey, and the Washington Department of Fish and Game.
The first September was spent on the central BC coast near Bella Bella. After locating the otters and watching where they fed and rested, we set shallow nets and waited anxiously for our first catch. We had no success for two days, but after some experimentation we began to catch them on the third day. Two days later, we had met our goal of 18 sea otters.
Handling them safely was challenging (they belong to the same family as the wolverine, after all!), but with help from Alaskan sea otter expert Jim Bodkin we quickly learned how to restrain them without getting bitten. We measured the length and canine tooth size of each animal we caught, assessed its physical condition, took blood, tissue and fur samples and then we let it go.
We were pleased to note that all of the otters we examined appeared to be in excellent physical condition, and none were injured during their capture. Upon release, each swam a short distance, then assumed its usual position on its back. Coloured flipper tags allowed us to recognize it after it rejoined its group.
In the second season, we focussed our efforts on the population of sea otters resident off northwest Vancouver Island, near Nuchatlitz Inlet. Benefiting from the experience gained the previous year, we captured, sampled and released 24 otters over the course of several days – including several mothers and their recently-weaned pups.
Laboratory analyses of the samples will be completed this winter. Veterinary pathologist Dr. Steven Raverty, from the BC Ministry of Agriculture and Foods, is conducting tests to determine the otter’s exposure to disease organisms; and Fisheries and Oceans scientist Dr. Peter Ross is testing their levels of PCB’s, dioxins and other contaminants. My job is to conduct DNA tests to determine once and for all whether the central coast otters represent a remnant population or whether it was founded by sea otters from the Alaskan transplants, and to measure genetic variability in both populations.
Stay tuned for final results – coming to AquaNews this spring!
Source: Vancouver Aquarium Marine Science Centre
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