Polar Bears, Their Prey and Human-related Pollution in the Russian Arctic

Andrei N. Boltunov

Three major alternating directions in Soviet/Russian marine mammal investigations are clearly distinguished. Faunal sketches written by earliest explorers of Arctic and Far-eastern seas describing met seals, walruses, whales and polar bears were characteristic for the 19th and the beginning of 20th centuries. In the 20th century marine mammal scientists paid great attention to perfecting methods of exploitation of marine mammal resources which seemed unlimited. Gradually people have understood that this resource is quite limited, slowly-recovering and, consequently, requiring a wise, cautious approach to its use and management. By the end of the 20th century in Russia as well as in the whole world scientists and the public have come to the realization that marine mammals are very vulnerable and must be protected and carefully managed. The threats facing marine mammals in Russia also have transformed considerably in recent years: human related pollution of marine ecosystems and habitat degradation have completely substituted for hunting, whaling and sealing as major threats to their survival.

In the 1990s Russian-American field research on polar bears was conducted throughout the Russian Arctic from the Chukchi Sea on the east to the Barents Sea on the west. The main challenge of the work was to delineate polar bear populations inhabiting the Russian Arctic and adjacent areas. Satellite telemetry was applied in the course of the studies. Polar bear females were caught and instrumented with satellite radio collars. Biological samples (blood and fat) were taken from all caught polar bears. Laboratory analysis of blood samples from 58 adult polar bear females caught in the Russian Arctic and 32 adult polar bear females caught in the Svalbard area were performed to assess the level of polychlorinated biphenyls (PCB) in their bodies. The highest ?PCB level was found in bears from Frantz-Josef Land (11,194 ng/g lipid weight) and the lowest - in the Chukchi Sea (2,465 ng/g lw). Geographic variation in the level of PCB congeners was also examined. Although the physiological effect of these compounds on the polar bear organism is not yet known, recent findings of polar bears with abnormal development of reproductive organs (pseudo hermaphrodites) indicate health problems in some populations of the species.

Since polar bears thrive on the blubber of their preys, the problem of biological transport and the accumulation of lipophilic pollutants is quite essential in order to understand how and from what sources polar bears get these dangerous chemicals. The ringed seal is the main prey for polar bears throughout the Russian Arctic, while in some areas bearded seals and walruses play an important role in the polar bear diet. In 1995 a Russian-Japanese team collected biological samples from 38 ringed seals hunted in the area of Dikson settlement (southern Kara Sea). The blubber samples obtained were analyzed for persistent organochlorine contaminants. It was revealed that DDT and PCB levels in the seals exceeded those found in seals of the Canadian and Norwegian Arctic. This indicated the presence of a local recourse of the compounds in study area. At the same time, levels of chlordane compounds (CHLs) and hexachlorocyclohexanes (HCHs) were close to those known for seals from other parts of the Arctic due to atmospheric distribution of the compounds throughout this part of the Globe.

The problem of human related pollution in marine mammals is essential not only for marine mammals themselves. In the Russian northeast (Chukotka) marine mammals are a very important food source for local communities. Aboriginal people of the region have the exclusive right to hunt not only seals but also walruses, grey and bowhead whales. According to the "Agreement between the Government of the United States of America and the Government of the Russian Federation on the conservation and management of the alaska-chukotka polar bear population" signed on October 16, 2000, in the nearest future they also will gain the right to hunt polar bears for subsistence and traditional cultural needs. All of these aspects call for the monitoring of human related pollution in these animals.