American Wildlands v. Dirk Kempthorne (Interior Dept.)

Jul 8: In the U.S. Court of Appeals, D.C. Circuit, Case No. 07-5179. As explained by the Appeals Court, the westslope cutthroat trout has historically inhabited rivers and streams across parts of Montana, Wyoming, Idaho, Oregon, and Washington. Its scientific name, Oncorhynchus clarki lewisi, pays homage to Lewis and Clark, the storied explorers who encountered the fish in 1805 at the Great Falls of the Missouri River. Plaintiffs maintain that interbreeding with other members of the trout family -- a phenomenon called hybridization -- has so imperiled the continued existence of the fish that the government should list it as threatened under the Endangered Species Act (ESA).

On appeal, plaintiffs argue that the government’s decision not to do so was arbitrary and capricious because the Agency included in its count of westslope cutthroat trout hybridized fish, which embodied the menace at issue. Plaintiffs also appeal the district court’s denial of their motion to supplement the record with letters supporting their case.

The D.C. Circuit said, "Although new data might require a future listing of the fish as threatened, we conclude the agency engaged in reasoned decisionmaking based on the best available science, and the district court did not abuse its discretion in refusing to supplement the record." The Appeals Court concluded, "Because American Wildlands has not shown that the Service’s decision to deny listing the westslope cutthroat trout as a threatened species was arbitrary or capricious, and because plaintiffs have not shown that the district court abused its discretion in denying the motion to supplement the record, we affirm the district court in all respects."

Access the complete opinion (click here).