## Facts

- Environmental organizations challenged the National Marine Fisheries Service (NMFS) treatment of hatchery-origin steelhead under the Endangered Species Act (ESA) for the Upper Columbia River steelhead evolutionarily significant unit (ESU).
- NMFS interprets ESA “species” to include distinct population segments and, for salmonids, uses ESUs defined by reproductive isolation and evolutionary significance.
- After criticism of earlier listing practices, NMFS adopted the Hatchery Listing Policy (HLP), directing NMFS to define ESUs to include both natural-origin and qualifying hatchery-origin fish and to consider all such fish when determining listing status.
- NMFS applied the HLP to define the Upper Columbia River steelhead ESU to include naturally spawning steelhead and related hatchery stocks and then listed the ESU as “threatened,” relying in part on hatchery fish in assessing overall abundance and extinction risk.
- Plaintiffs argued hatchery fish can harm natural-origin fish (e.g., genetic and ecological effects) and therefore should not be used to reduce the listing severity for the natural-origin component.
- Industry and water-user intervenors argued that, if hatchery and natural fish are within the same ESU, the ESA forbids NMFS from treating them differently in regulations.

## Issues

1. Whether the ESA permits NMFS, under the HLP, to include hatchery-origin fish and natural-origin fish within a single ESU and to consider the ESU as a whole in listing decisions.
2. Whether NMFS’s decision to list the Upper Columbia River steelhead ESU as threatened (rather than endangered), considering hatchery fish, was arbitrary, capricious, or contrary to law under the Administrative Procedure Act (APA).
3. Whether the ESA requires identical regulatory treatment of hatchery and natural fish once they are part of the same listed ESU.

## Decision

- The Ninth Circuit reversed the district court’s invalidation of NMFS’s “threatened” listing for the Upper Columbia River steelhead ESU.
- The court upheld NMFS’s Hatchery Listing Policy as a permissible interpretation of the ESA entitled to Chevron deference.
- The court held NMFS’s application of the HLP and its threatened listing determination were not arbitrary or capricious under the APA.
- The court affirmed that NMFS may distinguish between hatchery and natural fish in protective regulations even within a single listed ESU.

## Legal Principles

- When the ESA is ambiguous on a specific biological classification question, NMFS’s reasonable interpretation may receive Chevron deference.
- NMFS may define an ESU to include both hatchery-origin and natural-origin fish where the hatchery stocks are part of the same ESU, and NMFS may consider hatchery fish’s effects—beneficial or harmful—on ESU viability.
- ESA listing determinations must assess the status of the listed entity (the ESU) as a whole; the statute does not require NMFS to base listing status solely on a subset such as the naturally spawning component.
- The ESA does not require identical regulatory treatment of every individual within a listed ESU; NMFS may craft ESA § 4(d) protective regulations that treat hatchery and natural fish differently if aimed at conserving the ESU.

## Conclusion

The Ninth Circuit sustained NMFS’s approach to include qualifying hatchery fish within salmonid ESUs, to evaluate extinction risk at the ESU level when setting listing status, and to apply differentiated protective regulations within a single listed ESU consistent with ESA conservation objectives.


Trout Unlimited v. Lohn, 559 F.3d 946 (9th Cir. 2009)