Consistent Extinction Risk Assessment under the U.S. Endangered Species Act

• Published in: Conservation letters 2017-05, Vol.10 (3), p.328-336
• Main Authors: Boyd, Charlotte, DeMaster, Douglas P., Waples, Robin S., Ward, Eric J., Taylor, Barbara L.
• Format: Article
• Language: English
• Subjects: Bayesian analysis; Bayesian state‐space population model; Biodiversity; Biodiversity loss; Caretta caretta; conservation prioritization; Demography; Endangered & extinct species; Endangered species; Extinction; Fisheries; listing criteria; Population; population viability analysis; risk analysis; Risk assessment; Science; Species extinction; Threatened species; Wildlife conservation
• ISSN: 1755-263X; 1755-263X
• DOI: 10.1111/conl.12269

Identifying species at risk of extinction is essential for effective conservation priority‐setting in the face of accelerating biodiversity loss. However, the levels of risk that lead to endangered or threatened listing decisions under the United States Endangered Species Act (ESA) are not well defined. We used a Bayesian population modeling approach to estimate levels of risk consistently for 14 marine species previously assessed under the ESA. For each species, we assessed the risks of declining below various abundance thresholds over various time horizons. We found that high risks of declining below 250 mature individuals within five generations matched well with ESA endangered status, while number of populations was useful for distinguishing between threatened and “not warranted” species. The risk assessment framework developed here could enable more consistent, predictable, and transparent ESA status assessments in the future.