October 16, 2014

Help or Hindrance for Species Conservation?

Endangered Species Protection for the Pacific Fisher

I have mixed feelings about the proposed listing of the Pacific fisher as Threatened under the Endangered Species Act. The species seems to meet the biological criteria for listing —small, fragmented populations, victim of numerous threats, etc.—however the question in my mind is whether ESA protections may hinder more than help with species conservation and recovery.

I lead a team of experts that is developing an interagency conservation strategy to recover a remnant population of fishers in the southern Sierra Nevada.  Guided by an executive-level team from the state and federal wildlife agencies, the Sierra Nevada Conservancy, the US Forest Service, and the National Park Service, the effort is highly collaborative, with scientists, stakeholders, and land managers deriving solutions together using the best available science on fishers and their forest habitat.  The stakes are high, the problems complex—and conserving the population may mean short-term harm for long-term gain.  To use a medical metaphor:  we may have to harm the patient to save the patient.

Photo Credit: USFS Region 5

The Sierra Nevada population of about 250-300 fishers ranges from the south rim of Yosemite Valley down to the southernmost tip of the mountain range.  Historically, the species ranged well north of Yosemite, but fishers were extirpated from large areas by logging, fur trapping, and other human impacts.  Currently, fishers occupy densely forested habitat patches south of Yosemite Valley in a series of semi-isolated subpopulations separated by major river canyons—like the Kings and Kern. These fragmented populations face a bevy of threats, including increasingly large and severe wildfires, pesticide poisoning at illegal marijuana grow sites, roadkill, and climate change.

Although the well-publicized impacts of illegal rodenticide use on fishers and other wildlife are huge (for more see my recent blog), the largest and most difficult to manage threat may be uncharacteristically large and severe wildfires—like the 2013 Rim Fire and the 2014 Kings Fire—which can remove the fisher’s dense forest habitat over large areas and for long times. Complicating the situation, management actions necessary to reduce this risk—such as forest thinning projects—may do short-term harm to fishers, before the positive effects of the treatments are realized.  My fear is that ESA listing could therefore cause regulatory delays for management actions that science says may help save the fisher’s forest habitat from increasingly severe disturbance events.

I hope my fears are wrong.  The US Fish and Wildlife Service has one year to finalize their decision to list the species or not.  ESA protection may increase our ability to counter threats like rodenticide poisoning and intensive logging, but it is unclear how it may affect management actions intended to restore more natural and resilient habitat conditions in our altered forests. Whatever the final listing decision, our interagency fisher team will continue working toward solutions for sustaining and recovering this beautiful and essential member of the Sierra Nevada ecosystem.


Using occupancy and population models to assess habitat conservation opportunities for an isolated carnivore population

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Southern Sierra Nevada Fisher Assessment

Baseline evaluation of an isolated fisher population in the southern Sierra Nevada

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About the author:
Wayne Spencer, Ph.D.
Chief Scientist | Head of Science Leadership Team
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