Briefs Debate Method of Grouping Wild Salmon Populations 

Columbia Basin Bulletin

June 22, 2007  

Has the federal government erred by grouping wild salmon populations under Endangered Species Act listings that, because of their geographical separation, have little chance of kinship?

That is what the Alsea Valley Alliance alleges, and it's a topic being explored by U.S. District Court Judge Michael A. Hogan. He asked the NOAA Fisheries Service on May 18 to explain how it knitted together stocks from distant streams in making listing determinations.

Alsea and a host of other agriculture and other interest groups last year challenged the legality of NOAA's June 28, 2005 , listings of 16 salmon "evolutionarily significant units" in Idaho , California , Oregon and Washington .

The groups say that hatchery and naturally spawned salmon "swimming side-by-side in the same stream" were not treated equally in NOAA's listing decisions as the law requires. They have also argued that NOAA falsely included populations within the ESU that do not "interbreed when mature, another ESU mandate.

"Thus, NMFS' Listing Determination is both under-inclusive and over-inclusive," according to an Alsea request for summer judgment filed Nov. 13, 2006 . "NMFS lists salmon over a large geographical area in a single Distinct Population Segment (DPS) even though a salmon return to spawn to the individual rivers from which they originally spawned, and, as a result, salmon from different rivers do not interbreed.

"Yet, ironically, at the same time, NMFS treats as separate populations hatchery and 'naturally spawned' salmon that in fact cohabit the very same rivers and interbreed." Alsea has asked Hogan to set aside the listing determinations.

The parties to the lawsuit have completed rounds of briefing and Hogan heard oral arguments on April 17.

Last month the judge asked NOAA to "file supplemental materials indicating whether, and if so, how, the NMFS determined that populations of Pacific salmon within evolutionarily significant units (ESUs) listed under the Endangered Species Act (ESA) and challenged in this case interbreed when mature."

On June 15, the U.S. Justice Department and Trout Unlimited filed briefs with the court defending the inclusion of relatively far-flung populations in the same ESU listing. Trout Unlimited is a defendant-intervenor in the lawsuit.

The federal filing says that "legislative history suggests that the term 'interbreeds when mature' requires that members of the same species, subspecies or distinct population segments be capable of interbreeding when mature, not that they physically interbreed with all other members."

"Moreover, the record reveals that the subpopulations that make up the challenged ESUs do interbreed, at least on the long-term timescales relevant to ESU determinations," said Trout Unlimited. "Plaintiff Alsea Valley Alliance's ('Alsea's') belief that in order for an ESU to be valid every population within an ESU needs to interbreed with every other population in that ESU, in each generation, is contrary to both congressional intent and the best available science."

The federal brief said NOAA "applied its ESU policy to make this determination based on the best scientific data available to the agency. Among other things, NMFS considered genetic differences between populations, movements of tagged fish and identification of physical barriers to fish migration to determine if populations are reproductively isolated.

"NMFS' genetic analyses showed that salmon within ESUs engaged in significant interbreeding over time. Thus, NMFS' carefully determined the composition of the ESUs based on the best scientific data available and its decision should be upheld," according to the federal filing.

The Alsea summary judgment request used as an example the Lower Columbia River chinook ESU which "consists of 31 populations over an area roughly 130 miles long (approximately 65 miles on either side of Portland, Oregon) and about 120 miles wide (from the Pacific Ocean to the Cascade Mountains).

"Some populations in this ESU spawn in the spring while others spawn in the fall. NMFS has not provided any evidence that members of the sub-populations interbreed with one another, and thus qualify as a single DPS."

The federal filing said that that the "extent of interbreeding is also a continuum that varies greatly over time." Straying from a population in one stream to another can happen often, or seldom, and straying from one population to another has been witnessed over relatively long distance.

"While the percentage of straying is often small in one generation, over the course of many generations, straying can be significant enough to ensure that members of populations share similar traits over large distances. Conversely, if there is little or no straying between local populations, they may develop different traits over the course of many generations even though they are still capable of interbreeding."

To account for that fact, NOAA's ESU policy says a population or group of populations of a West Coast salmon species will be considered a DPS if it: "(a) is substantially reproductively isolated from other conspecific population units; and (b) it represents an important component in the evolutionary legacy of the species."

The federal filing says NOAA uses data from protein electrophoresis or DNA analysis, habitat differences and phenotypic/life-history traits such as size, fecundity, and age and time of spawning to determine if populations had a shared legacy -- "genetic variability that is a product of past evolutionary events and that represents the reservoir upon which future evolutionary potential depends."

NMFS used observations of migration of members of one population to the spawning areas of another population and inferences of interbreeding among populations due to their genetic similarity -- in finding that populations within an ESU interbreed substantially over multiple generations, the federal brief says.

The federal brief says NOAA's 198 Chinook Status Review "shows the overlap of the range and peak times of spawning" for various stocks that can result in straying between populations of different temporal runs. It used as an example Nisqually runs highlighted in the Alsea summary judgment motion. The spawn-time range of Nooksack falls overlaps with Nisqually springs in the second half of September.

Hogan's courtroom has been host in the past for legal arguments over ESA listings, most debating how and/or whether naturally produced vs. hatchery fish of a like genetic strain should be considered in assessments of stock status.

A 2001 decision Judge Hogan said that the ESA forbids NOAA defining a "designated population segment" that includes both hatchery and naturally spawned and then failing to list the hatchery component. In that lawsuit, the Alsea Valley Alliance challenged the Oregon Coast coho listing.

The decision prompted a NOAA review of all of its West Coast salmon and steelhead stocks and its policy dealing with consideration of hatchery fish in making listing determinations.

The new hatchery policy and listing determinations were issued in 2005 with many hatchery stocks included in the listings but the determinations ultimately made on the basis of the wild stocks' status. Alsea says that making that distinction is illegal under the ESA. It also argues that it is unlawful to exclude a portion of the ESUs – hatchery fish – from ESA take prohibitions.

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