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Smoking Them Out

image of Sharon Levy
THE FISHER KING Ecologist Mourad Gabriel holds one of the threatened animals he researches.
To study an elusive species, Mourad Gabriel must track it down -- and evade angry pot farmers

Hiking through the northern California woods in the course of doing his job, Mourad Gabriel frequently encounters angry men who are unhappy to see him. They're marijuana growers, illegally using federal and tribal lands in remote, hard-to-reach locations. And their reactions to seeing him may range from yelling at him to brandishing their pistols or Kalashnikov rifles and posting his home address on a cannabis blog -- along with the ominous observation that "snitches end up in ditches."

Gabriel isn't with the Drug Enforcement Administration or any other law enforcement agency. He's a wildlife disease ecologist nearing the completion of his doctorate at the University of California, Davis, who has spent a decade studying fishers -- furry, elegant predators the size of large house cats. Fishers once roamed our northwestern forests in abundance, but their numbers have dwindled dramatically in the region. Now Gabriel, 38, believes he has unlocked the mystery as to what's keeping this species from bouncing back. And his discovery, alas, is what has outlaw pot growers reaching for their guns (or computer keyboards).

"I'm not focused on the pot plants," Gabriel says. "What makes my blood boil is the environmental damage being done on public land."

Hit hard by fur trapping and the logging of the forests they favor, fishers had all but vanished from their historic range by the early twentieth century. Gabriel describes them as an "umbrella species," meaning that they tend to be good indicators of their ecosystem's overall health. By studying the remaining fishers closely, biologists can get a sense of how other members of their ecosystem are faring.

In 2004 Gabriel was engaged in a study of predators on land owned by the Hoopa tribe in northern California's Humboldt County. To his surprise, the fisher population on the reservation had declined precipitously in the years since a survey was made in the 1990s. Gabriel knew that fishers need mature forest to survive: they rest and raise their young inside the cavities found in the trunks of very old trees. The reservation still boasted plenty of ancient oaks, chinquapins, and Douglas firs. Why, he wondered, weren't more fishers living there?

"Some of the fishers we were radio-tracking had died of rodenticide poisoning," Gabriel recalls. "I couldn't imagine how that had happened, since fishers live far from cities or farm fields." He made the connection to industrial-scale marijuana farms after some members of the Hoopa tribal police showed him photos of grow sites they had dismantled after raids. Pesticide containers were scattered across the landscape, their poison baits marked with countless scratches made by the gnawing teeth of mice and rats. The pot growers, it soon became clear, were spreading large amounts of rodenticide around their plants to protect them from tiny pests. The rodents were living for several days after eating the poison -- just long enough to be preyed on by fishers.

Gabriel began to document the stunning quantities of rodenticide that were peppering the 144 square miles of the Hoopa reservation. On one grow site near the reservation, 90 pounds were discovered. He calculates that 10.5 pounds (the amount he found at one of the first sites he studied) is enough to kill 12,542 deer mice or 1,792 wood rats -- and anywhere from 5 to 28 fishers. Over the next eight years, on both Hoopa and national forest land, the rodenticide-linked casualties kept piling up.

In addition to legal pesticides that are already in wide use, significant amounts of banned pesticides, including DDT and carbofuran, have been found at abandoned sites. Gabriel has also seen signs of illegal clearcutting and stream diversion. "No law seems to sway these individuals," he says.

His research has led him to conclude that the same rodenticides killing fishers pose a grave threat all the way up the forest food chain. If the problem is left unaddressed, he says, the result could be a biologically devastated forest -- one where no fisher or bobcat hunts and no bird sings. As he continues with his research, he has also begun collaborating with a group that works to clean up contamination at dismantled grow sites.

"The rogue pot industry is a human problem," he says. "And we're going to need a human solution."

image of Sharon Levy
Sharon Levy spent a decade working as a field biologist in the woods of Northern California before taking up science writing full time. She is a regular contributor to National Wildlife and BioScience, as well as the author of the 2011 book Once and ... READ MORE >
this is an argument for legalization and regulation of the cannabis industry. After all you can not regulate that which is contraband. So long as the feds continue to raid pot clubs and growers it is difficult to tell them to abide by environmental laws.
probably just getting the local,state gov involved would add enough nuisance laws to hold at bay some of the toxic crap being used,hopefully but then again it is the gov
Dear Sharon, I read your article with interest as the problem is well known by some here in California. However, I wish you had put the word 'Rodenticide' front and center in the title. You address three important issues: The demise of the Fisher population, illegal pot farms and, rodenticides. Unfortunately, As Mourad surely knows, rodenticides are having a huge, negative impact upon Fishers (as well as many other animals)yet the word ‘rodenticide’ was buried near the end of the first page. Had you placed the word ‘RODENTICIDE’ in the title, I would have made an enlargement of that page and used same as a poster when promoting the hazards of these poisons. Keep up the good work but don’t be afraid to address this issue loud and clear. Thank You. Rodenticide Free Project – P.O. Box 892, Bolinas, CA 94924