On November 23, 2010, in Humane Society of the United States v. Locke, the U.S. Court of Appeals for the Ninth Circuit held (pdf) that NMFS violated the Marine Mammal Protection Act (MMPA) by failing to adequately explain its finding that sea lions are having a “significant negative impact” on the decline or recovery of salmonid species listed under the Endangered Species Act (ESA) in the Columbia River. The ruling invalidated NMFS’s decision authorizing the states of Washington, Oregon, and Idaho to lethally remove California sea lions from the Bonneville Dam area. The 2008 decision (pdf) allowed the states to take the lesser of either 85 sea lions per year, or the number required to reduce the observed predation rate to one percent of the salmonid run at the dam. The authorization had been provided pursuant to section 120 of the MMPA, which allows “the intentional lethal taking of individually identifiable pinnipeds which are having a significant negative impact on the decline or recovery of salmonid fishery stocks which . . . have been listed as threatened . . . or endangered species under the [ESA].”

The court based its decision, in part, on the fact that NMFS had previously determined that fisheries that caused similar or greater mortality among the same salmonid populations were not having significant negative impacts. Specifically, NMFS had twice concluded in 2007 that the taking of ten percent of the local salmonid populations would not appreciably reduce the likelihood of recovery of the listed species. The Ninth Circuit reasoned that, absent a satisfactory explanation from NMFS, it was unable to reconcile this conclusion with the NMFS decision at issue, which determined a predation rate of one percent would negatively impact the listed species. In finding that NMFS failed to adequately explain these disparate factual determinations, the court ordered NMFS to provide an explanation sufficient to permit meaningful judicial review. According to the Seattle Times, NMFS is disappointed by the decision but hasn’t decided on its next step.