America’s “War on Drugs” has claimed many casualties, but one group impacted by drug policy has no history of use, sale, or possession; it even lacks the opposable thumbs needed to roll a joint. The Pacific fisher (Martes pennanti), a rare relative of otters and minks native to the West Coast, is in danger of extinction due to chemical use at illegal marijuana cultivation sites in the Sierra National Forest, one of its crucial habitats.
The use of marijuana for medicinal purposes is legal in the state of California, but the drug is still considered a Schedule I substance under U.S. law, and federal agents continue to destroy hundreds of thousands of plants in the region every year. These raids have pushed some growers to establish grow sites on isolated portions of public lands such as forests and parks, which are more difficult to patrol. Operating outside any regulatory framework, these grows pose a number of environmental hazards, including watershed pollution, habitat destruction, and wildfire risk.
According to Craig Thompson of the U.S. Department of Agriculture Forest Service, a previously unrecognized problem is the unregulated use of rodenticides, or rat poisons, to prevent damage to marijuana plants. These poisons can impact a wide range of nontarget species, including the Pacific fisher. Thompson and his colleagues tracked fishers using radio collars over a five-year period, monitoring their home ranges and performing autopsies on any that died during the study. Of the 46 deceased animals analyzed, 39 (85%) tested positive for a rodenticide. When the home ranges of these fishers were examined, the scientists found that they contained significantly more illegal marijuana grow sites than the ranges of fishers that tested negative for the poisons. As the animals rarely entered into legitimate agricultural lands or human-inhabited areas, the team hypothesized that the grow sites were the sources of the rodenticides.
Although only one fisher died directly due to rodenticide poisoning, lower doses of these compounds still have dangerous effects. Sluggish reflexes, reduced rates of healing, and even brain damage can all result from exposure to rodenticides, rendering the fisher more vulnerable to starvation and infection. As Thompson explained, “By increasing the number of animals that die from supposedly natural causes, these pesticides may be tipping the balance of recovery for fishers.” The species is currently a candidate for protection under the Endangered Species Act, and its estimated U.S. population as of 2012 (roughly 4,600) is far under its historical numbers.
Regulating the environmental effects of marijuana production is impossible when production itself is outlawed. By providing a proper legal framework for marijuana growers, officials can create a more sustainable and environmentally friendly market, benefiting humans and fishers alike.