The initiative is working with Mourad Gabriel, a doctoral candidate at the University of California at Davis Veterinary Genetics Laboratory and president of the Integral Ecology Research Center in Blue Lake, Calif., who was lead author on a study published last year that established fishers were getting poisoned. The study found 46 of 58 dead fishers sampled from the southern Sierras and Northern California — 79 percent — carried one or more of the rat poisons, including a female that passed it on to her babies through her milk. The first was found in 2009 on the Sierra National Forest just south of Yosemite.
"It just looked like it died in its sleep," said Gabriel. "We brought it in and found a massive amount of bleeding throughout all the cavities."
Tissue tests showed large amounts of poisons known as secondary anticoagulant rodenticides, the compounds used in commercial rat poisons.
Necropsies determined that of the 46 dead fishers carrying rat poison, four of them died from the chemicals. After the study concluded, researchers determined that two more fishers from Northern California had died from rat poison.
All the dead fishers were found because they carried GPS tracking collars that sent out a death alarm.
"It would not be farfetched to think that non-monitored fishers are also being exposed and poisoned as well," Gabriel said.
Yaeger said rat poisons have also been found in fishers in Washington, but it is not known if they picked it up in British Columbia before being relocated.
Gabriel said researchers in his study looked for rat poisons around remote cabins and campgrounds, power pole rights-of-way, and private timber plantations. The only places they found them — as much as 90 pounds at one site — were illegal marijuana gardens.
An EPA assessment says the poisons have also been found in endangered San Joaquin kit foxes, mountain lions, bobcats, owls, hawks, eagles, crows, squirrels, raccoons, and deer.
"If this continues, I don't think this will be the only species" considered for protection due to illegal pot plantations, Gabriel said.