DENNIS D. MURPHY and PAUL S. WEILAND
The US Fish and Wildlife Service and National Marine Fisheries Service recently proposed to amend existing regulations that implement the Endangered Species Act’s by using surrogates to express the amount
or extent of incidental take of listed species. They propose the use of surrogates, either in the form of a substitute species filling in for a species that is challenging to observe or measure, or a habitat attribute, as proxies for the amount or extent of anticipated take. The authors contend that the proposed rule lacks essential implementation details and describe five essential steps in surrogate selection and validation.