GRANTS PASS, Ore. — For the first time, federal biologists are assessing whether illegal marijuana gardens in the back woods of the West could threaten the extinction of a wild animal.
The object of their attention is the fisher, a small but fierce forest predator related to the weasel.
The U.S. Fish and Wildlife Service is interested in rat poisons used at the thousands of illegal pot plantations that overlap the fisher’s range on national parks, national forests, and Indian reservations. Though only a handful of fisher deaths in California have been blamed directly on the poisons, nearly 80 percent of those examined in one study were found with the poisons in their systems. Scientists think fishers get poisoned from eating rats that eat the poisons, which are spread around young marijuana plants and irrigation systems by the pound.
“We absolutely do have to evaluate the marijuana threat,” said J. Scott Yaeger, a wildlife biologist for the U.S. Fish and Wildlife Service in Yreka, Calif., who leads the team of scientists doing the Endangered Species Act review. “We need to make that link, or if the information can be discredited, we would do so in this evaluation. My gut feeling is, though, we are going to find a strong link.”
Based on their evaluation of existing research, Fish and Wildlife is due to decide whether to list West Coast fishers as a threatened or endangered species by the end of September 2014
The fisher is common across Canada and the Northeast U.S., but not in the West, where fur trapping, logging and the spread of people into the dense forests where it lives have caused numbers to plummet.
Biologists estimate 3,000 to 5,000 remain in California, Oregon and Washington. They make up what is known as a distinct population segment, which qualifies for protection, though healthy populations exist elsewhere.
Up to 3,000 still live in the Klamath Mountains overlapping the Oregon-California border. Studies by the Hoopa Valley Tribe have found female numbers rising, but not males, said tribal biologist Mark Higley.
About 300 are in the southern Sierra Nevada in California, from Yosemite National Park south. A U.S. Forest Service study found their numbers stable.
Smaller populations were introduced on the Olympic Peninsula in Washington and the southern Cascades of Oregon.
The fisher was formally classified in 2004 as a candidate species, likely worthy of protection. After conservation groups sued, Fish and Wildlife agreed to a timetable for evaluating 250 species.