The Ninth Circuit Court of Appeals just affirmed the use of geographic sub-regions to determine the impact of commercial fishing on critical habitat and population levels. The case is Alaska v. Lubchenko and the opinion can be found here.
From the court's summary:
The panel affirmed the district court’s judgment rejecting the claims of fishing industry representatives and the State of Alaska in an action challenging limitations to the commercial fishing industry the National Marine Fisheries Services placed on sub-regions of the Pacific Ocean inhabited by the endangered western Distinct Population Segment of Stellar sea lions.
The panel held that use of sub-regions did not violate the Endangered Species Act and that the agency utilized appropriate standards to find that continuing previous fishing levels in those sub-regions would adversely modify the critical habitat and jeopardize the continued existence of the entire population. The panel also held that the district court did not err by refusing to order preparation of a Record of Decision pursuant to the National Environmental Policy Act because it would be premature in the absence of the agency’s proposed action based on the Environmental Impact Statement record it develops.
In the case, the federal government used the "western Distinct Population Segment" of the Steller Sea Lion in Alaska. Two of the seven sub-regions have experienced population declines attributed to nutritional stress. The National Marine Fishereise Service limited fishing in those areas, which prompted this lawsuit.
At issue was whether the Endangered Species Act precluded the use of a sub-region approach to species health as opposed to a species-level inquiry. The argument was that the species as a whole has a different population trend than a sub-region. Analyzing the Endangered Species Act, the court ultimately held that the government could use sub-regions.