|Endangered Species of Canada Stories by the Edmonton Journal, December 1999
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A GUIDE TO WILDLIFE AT RISK
The Committee on the Status of Endangered Species, a federal advisory group, has created a list of 340 animals and plants that are in some jeopardy. Here are the categories the committee uses:
Extinct The species no longer exists in Canada
Extirpated A species no longer exists in the wild in Canada, but can be found elsewhere.
Endangered A species that faces imminent extirpation or extinction.
Threatened A species likely to become endangered if limiting factors are not reversed.
Vulnerable A species of special concern because of characteristics that make it particularly sensitive to human activities or natural events.
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The Edmonton Journal
November 29, 1999.
Polar pollution, climate change bode ill for bears
Conservation accomplishments could be undone in the future
Journal Staff Writer
POLAR BEAR THE GREAT WHITE WANDERER
In the spring of 1996, Canadian scientist Andy Derocher was conducting research on polar bears on the Norwegian islands of Edgeoya and Hopen at Svalbard when he came upon something entirely unexpected.
Two female yearlings he had captured had dual genitalia. Neither of the animals showed signs of a Y chromosome, so both animals were regarded as female pseudo hermaphrodites.
Derocher was nonplussed. Although the disorder is rare, it is known to occur infrequently in black bears and most other mammals. But over the course of the next two years, he found six more bea5rs with the same disorder, which suggested that as many as 80 of Svalbards estimated 2,000 bears might be similarly affected by the disorder which could be caused by pollution.
For an animals that spends most of its time on the sea ice in some of the worlds most cold and hostile environments, the polar bear has fared reasonably well in spite of some setbacks.
With the advent of automatic rifles and snowmobiles, hunters knocked back the worlds population, and by the 1960s, the great white wanderer was in serious trouble.
However, with the co-operation of industry and Inuit hunters, worldwide conservation efforts over the past century have brought back the population to between 25,000 and 30,000 animals, with 15,000 in Canada.
Today, Canadas polar bear populations are considered to be healthy but vulnerable.
Ian Stirling, the Canadian Wildlife Service scientist who has studied polar bears longer than anyone else, believes that climate change, hunting pressures and the kind of gender bending contaminants that may be affecting Svalbards bears, could undo all of the conservation accomplishments that have been made if we do not continue to monitor populations carefully.
"On a worldwide basis, polar bears are not in any immediate danger," says Stirling. "But if somewhere down the road, we get too complacent and miss subtle or more serious problems, that could all change rather quickly."
Derocher, who once worked with Stirling in the Canadian Arctic and continues to collaborate with him today, isnt sure yet what to make of what he has found in Svalbard.
"The disorder we discovered may result from natural causes, but given the high levels of pollution in polar bears from Svalbard and the Barents Sea, I am concerned that toxic chemicals might be involved."
With the exception of Russia, where PCBs are reportedly still being used, these contaminants have been banned in the rest of the world since the early 1970s. The problem is that it takes decades for PCBs and other organochlorine compounds like them to break down in the environment. They are also lipophilic, which means they are attracted to, and stored in the fat of the smallest invertebrates.
Concentrations continue to increase as you go up the food chain through larger invertebrates, fish, seals and finally bears. Contaminants such as PCBs can mimic, block or disrupt the function of reproductive hormones in wildlife.
Canadian scientists are now looking into the situation more closely to see if our own polar bears are at risk.
Ross Norstrom, a chemist scientist working for the Canadian Wildlife Service, says the key is to define the food webs that lead to higher levels of contamination.
"The problem is conducting toxicology research on an animals like the polar bear which is widely dispersed in a very hostile environment," says Norstrom.
"Apart from getting samples from Inuit hunters, the only other option for collecting samples of tissues from bears would be to collect them ourselves which is unacceptable."
New testing techniques
With recent advances in the study of how the immune and hormone systems may be affected by chemical contaminants, there are now other ways of finding out whether polar bears are affected by contaminants.
In August 1998, Derocher captured, radio tagged, and vaccinated 35 bears to test the immune function of the animals, hoping that it might eliminate concerns about the PCBs or other toxins. The animals in this case are injected with a dead vaccine that has no impact on their health. They are then recaptured, so that blood tests can be drawn to measure how well the immune system is working.
The results, however inconclusive thus far, suggest that polar bears might be at risk.
Although not immediately lethal, a weakened immune system could make the polar bear more vulnerable to disease and malnutrition. While Canadian bears do not appear to have nearly the levels of PCBs found in the Svalbard animals, Stirling plans to repeat the study on the polar bears of western Hudson Bay.
"We know that contaminant levels are the highest in the world in Svalbard while they are much lower in western Hudson Bay," says Stirling.
"So, the idea is that we inject the same vaccines into similar numbers of bears in both areas."
Both Svalbard and western Hudson Bay have similar sized polar bear populations. The major known variable between them is the contaminant level.
Therefore, if the scientists find significant differences in the immune system, or hormonal effects, in the Svalbard bears, then high contamination is the likely cause.
This is the first time anything like this has been done in wild populations, and raises the research of polar bears to a new level of sophistication.
Stirling, however, has other concerns to consider. Up until recently, the bears of the southern Hudson and James Bay region have been the most productive polar bears in the world.
Studies by Stirlings research teams have shown that in some years, up to 40 per cent of the females may wean their cubs at one and a half years of age rather than the two and a half years which is normal in all other areas where they have been studied.
This means that some of the females can reproduce after two years, a year sooner than polar bears in other parts of the world. Their litter sizes are also generally larger, and the cubs are often on their own before they are two years of age.
But in the early 1990s, Stirling and Derocher found fewer cubs surviving while bears of all ages were maintaining less of the body fat that is critical to their survival, especially during the four months of the year when melting ice forces them on to land where there is little or no food for them.
Less time on the ice
Initially, both scientists were at a loss to explain what was happening. Pollution was considered a possibility as were undetected changes in the seal population, which constitutes 90 per cent of the polar bears diet.
But on an educated hunch that bears might not be getting as much so called ice time to hunt seals and build up their fat reserves, the scientists turned to changes in the climate of the region. The winter of 1991-92 provided them with an opportunity to test the theory. Given that it was a particularly cold one, the bears should have had more time that winter to spend hunting on the ice. And sure enough, fatter bears were what they found in the fall of 1992.
In the hopes of getting a glimpse at the bigger picture, Stirling and his colleague Nick Lunn hired science grad John Iacozza, who had just finished analyzing information on sea ice from satellite images, to look at the long term trends associated with freeze up and break up in the region.
What Iacozza found was that over the 20 year period, the breakup of Hudson Bay has moved forward by about 10-14 days.
"Its not yet had any detrimental impact on the size of the polar bear population in western Hudson Bay," says Stirling. "But there have been changes. These bears used to be the most productive in the world. Now theyre in line with other populations. That, of course, could change if the trend to warming continues over the next 20 years, and we get conditions that allow for even less time for the bears to hunt on the sea ice."
The causes of global warming have been well documented. Since 1950, there has been a tripling of carbon dioxide emissions worldwide and an increase in temperatures of about one degree. If current climate models prove to be correct, the prognosis for the future of polar bears in southern Hudson and James Bay looks to be a grim one.
With a projected doubling of carbon dioxide emissions, for example, temperatures are expected to rise by another 1.5 C to 4.5 C worldwide within the next half century.
In the Arctic and sub Arctic regions, however, where the intensity of radiation reflecting off the snow and ice is likely to be heightened by greenhouse gases trapping the warm air as it rises into the atmosphere, those same computer models suggest temperatures could rise by up to 2C in summer and 10C in winter
Fear of warmer winters
Such a sustained warming trend may well affect polar bears further north as well if it facilitates year round shipping through the Northwest Passage where significant polar bear numbers are found in winter and spring.
Warmer weather, and particularly the possibility of rain in late winter or early spring, might also cause polar bear dens to collapse.
For Stirling, climate change, pollution and the ever present need to ensure hunting pressures are carefully controlled should serve as a wake up call to wildlife managers everywhere.
"Polar bears are not like lemmings or hares," he says. "They reproduce very slowly. If the population declines to a very low level, it may be difficult for them to recover." Still, Stirling is optimistic about the polar bears immediate prospects".
"Our ability to document changes in the bears environment and evaluate their responses is still in its infancy, yet it is vitally important because what we see in the bears can tell us so much about changes in the Arctic marine ecosystem.
"Being able to monitor the responses of even one or two populations over at least the next 20 years or so is critical and expensive if we are to continue to be able to conserve and manage this species responsibly for all Canadians."