A study commissioned by the state Department of Environmental Protection says it would be expensive and ineffective to try to control New Jersey’s black bear population using birth control, according to a published report. The study, written by three experts in wildlife contraception, comes as Gov. Jon S. Corzine is considering whether the state should go ahead with a bear hunt this December or whether it should explore other options to control the number of bears. “Fertility control does not look like a viable option,” one of the report’s authors, Mark A. Fraker, a wildlife biologist with TerraMar Environmental Research in Ashland, Ore., said. According to the study, capturing bears so they could then be sterilized or given a fertility vaccine would be prohibitive because it costs about $1,000 per animal to snare them. Also, while the birth control efforts have worked on deer and wild horses, the wildlife experts said they have never been tried on bears in the wild. New Jersey’s bears are concentrated in the northwestern part of the state but have been spotted in all of New Jersey’s 21 counties. Proponents of a black bear hunt say it is the only method to control the animals’ numbers and to limit contact between the bears and humans. But opponents of the hunt say the state should put more effort into keeping the bears away from garbage such as requiring residents to use bear-resistant waste containers.