Manitoba’s Polar Bears in a Changing Climate. Dr. Stephen Petersen has been a wildlife biologist for more than 20 years and the Director of Conservation and Research for Assiniboine Park Zoo for the last 10 years. The Conservation and Research Department runs active field and zoo -based programs from the labs and offices at the Leatherdale International Polar Bear Conservation Centre. His department has a strong focus on the ecology, behaviour, and genetics of Arctic marine mammals and has been conducting research in Churchill for almost a decade.