From Arctic Focus: Study confirms what is already known: the Arctic polar bear is in trouble Focus reports on research into bear nuitrition in the Beaufort Sea (off of Alaska and Canada):
During April and May of 1985, 1986, 2005 and 2006 Cherry and his team used tranquilizer darts in order to immobilize the bear in order to measure the ratio of urea to creatine in their bloodstream. When an animal is fasting this ratio will be low, something that is normally only seen in male polar bears during the spring mating season. During the 1985 and 1986 studies showed the number of bears fasting was 9.6 and 10.5. In 2005 and 2006 this number had reached 21.4 and 29.3 percent, respectively.