The contentious plan to drop rodenticide on the Farallon Islands narrowly made it past a key regulatory hurdle last week. The California Coastal Commission approved the mouse eradication project, which will involve dropping 1.4 tons of poison-laced bait pellets from a helicopter, after seven hours of impassioned public comments and deliberation last Thursday. 

In a 5-3 vote, the commissioners conditionally concurred with the United States Fish and Wildlife Service’s federal consistency determination, tacking on a few new requirements, including an opportunity for commissioners to vote again once the plans are finalized. By the end of the evening, none of the commissioners seemed to relish the decision they made. 

“Human beings created this problem, and now I think we have a responsibility to make an incredibly tough decision to fix it,” Chair Donne Brownsley said. “…This is a really difficult and really unwanted decision by all of us, but I think that the risks to that biodiversity, to that island as a wildlife sanctuary, unfortunately is dependent on this action.” 

The decision allowed Fish and Wildlife to continue its march toward the eradication project, which has been in the works for 16 years.  

“We appreciate that supporting the project could be a difficult decision for the commission, as this course of action was a difficult decision for us,” said Gerry McChesney, manager of the Farallon Islands National Wildlife Refuge. Yet he said the complete eradication of mice from the islands is urgent and no other methods would be as thorough, safe and effective. 

Invasive house mice have been a growing problem on the South Farallon Islands since they were introduced by European ships in the 19th century, and now the islands have some of the densest mouse populations anywhere on earth. Federal officials at the Farallon Islands National Wildlife Refuge say the population is wreaking havoc on the fragile and diverse island ecosystem, threatening local seabirds and other species. The bountiful mice attract a handful of burrowing owls, which then turn to other prey, including the ashy storm petrel, a small seabird that depends on the islands for nesting. Though not endangered, the petrel has become a special focus of the operation, since half of the world’s population nests on the Farallones and its numbers have been in decline since the mid-2000s. 

The refuge has concluded that it must completely and permanently eradicate the islands’ mice and, using research from Point Blue Conservation Science, it created a plan that echoes a largely successful Anacapa Island rat eradication project from 2003. The service will haze gulls, which are at risk of secondary poisoning, away from the islands before and during the operation, and temporarily capture migratory raptors. A helicopter will then fly over the islands twice in the fall of 2023, outside the most significant seabird and pinniped breeding season, dropping grain pellets laced with brodifacoum-25D. Staff will place pellets by hand in hard-to-reach areas, and will later collect mouse carcasses by hand to prevent them from being eaten. 

The coastal commission first considered the rodenticide plan in 2019, but Fish and Wildlife withdrew the plan after commissioners voiced concerns. After the agency returned with revised contingency plans this year, the coastal commission’s staff recommended approving the federal consistency determination, a decision Cassidy Teufel, an environmental scientist for the commission, said was “not arrived at lightly.” 

The agency will have to hire an independent observer of the bait drop and gull hazing who will report back to the commission, and it must create a more comprehensive plan for a worst-case scenario—a poison spill. Last week, when commissioners voted to approve the project, they added more conditions: a stormwater runoff management plan and an option for the commission to hold another vote to reopen the matter if the final plans are unsatisfactory. 

The plan has garnered an increasing number of opponents, and by last week’s meeting, dozens of people representing organizations across California had prepared comments. The online hearing was so well attended that organizations were given only two minutes to speak and individuals had only one minute. Many objected to the basic premise of the plan, arguing the mouse situation was not an emergency and that the risks of the project far outweighed the benefits. Others questioned the threat to ashy storm petrels and the agency’s choice to use brodifacoum rather than a contraceptive bait. A California law passed last year banned most uses of anticoagulant rodenticides like brodifacoum, with exceptions for conservation uses like the Farallones plan. 

Commenters read messages from high-profile opponents like former Secretary of Defense and California representative Leon Panetta, who raised concerns over ocean health, and primatologist Jane Goodall, who said the poison would inflict pain and suffering on many sentient animals, including non-target species.

Sara Wan, a former coastal commissioner who is now the executive director of the Western Alliance for Nature, delivered an emotional appeal to the commissioners to deny the project, urging them to look at the whole ecosystem. She said that protections for the environmentally sensitive area shouldn’t revolve solely around any one species, and that the ashy storm petrel is not endangered. 

“You’re being pushed because you’re told this is an emergency and this island will be devastated if you don’t act,” Ms. Wan said. “Do you really know this is true?”

Ms. Wan said the choice should make the commissioners uneasy, and that they should go with their gut feeling. “Don’t hold your nose and vote because you believe you have no choice,” she said.

Another prominent critic of the plan, Richard Charter of the Ocean Foundation, compared the impacts of the project to the October oil spill off the Southern California coast. “In the context of the recent tragic Orange County experience, the very idea that we are here today to debate whether or not to approve what amounts to a deliberate spill of the worst possible, highly concentrated ecosystem poison amidst the most carefully protected coastal waters in the world is, in a word, amazing,” he said. 

Alison Hermance, the communications director for WildCare, said the San Rafael wildlife hospital opposes the plan because it treats many animals that have been exposed to rodent poison. While Fish and Wildlife is attempting to restore the ecosystem, she said, “our concerns are about death and damage to individual animals.” 

A group of fishermen also raised concerns about the health of local fisheries. Fishing around the islands is strictly limited by the surrounding marine protected areas, but the Southeast Farallon Island State Marine Conservation Area is a productive salmon trolling area. Even if the brodifacoum doesn’t harm any local fish, the perception of poisoned waters could hurt their business, some fishermen worry. 

“Our highly valued crab and salmon could be adversely affected for years to come,” Dick Ogg, a commercial fisherman in Bodega Bay, said. “Our livelihood is derived from the ocean. We are the true conservationists.” 

But environmental groups were far from universally opposed to the plan. Representatives from organizations like the National Audubon Society, Marin Conservation League and the Center for Biological Diversity said eradicating invasive species is one of the key elements of protecting biodiversity, especially in unique island ecosystems. Scientists from Point Blue, which contributed research to the project, said the project would allow ashy storm petrels and other species to flourish, with minimal negative side effects. 

“We would never endorse a project that we thought would have lasting negative impacts on the existing wildlife,” said Pete Warzybok, Point Blue’s Farallon program manager. 

When the commissioners got their chance to speak, none spoke with certainty or conviction about the plan. Several voiced their disappointment in how little eradication techniques had changed since they first reviewed the plan two years ago, or since the 2003 Anacapa Island project. 

“It’s really difficult to accept that this is the best that’s out there,” Commissioner Mark Gold said, calling the choice “one of the hardest decisions that the commission has had to face.” He called for a plan for more specific stormwater runoff mitigation strategies, to which Fish and Wildlife agreed.

Commissioner Roberto Uranga was more disparaging. “I’m disappointed that between then and now, we haven’t come up with a different way, or different options of being able to deal with this,” he said. “We’ve made no progress whatsoever.”

But others, including Commissioner Katie Rice, a Marin County supervisor, said they trusted the exhaustive research that went into the project and were heeding the calls from environmental organizations. “They’re all saying it shouldn’t wait any longer,” Supervisor Rice said. 

Eventually, the commissioners largely agreed that another informational meeting and close independent monitoring of the project would ease the decision. “If we’re wrong, and something terrible happens,” Commissioner Shelley Luce said, “I want to know that I was wrong in supporting this.”