Office of External Affairs
Mountain-Prairie Region


U.S. Fish and Wildlife Service
Mountain-Prairie Region
134 Union Boulevard
Lakewood, Colorado 80228

September 8, 2010                                              

Mark Wilson 406-449-5225                                                                                                              
Leith Edgar 303-236-4588

Listing of the Arctic Grayling Under the ESA Is Warranted

The U.S. Fish and Wildlife Service (Service) announced today that listing the upper Missouri River basin Distinct Population Segment of Arctic grayling, as threatened or endangered under the Endangered Species Act (ESA) is warranted, but that listing the fish is precluded at this time by the need to complete other listing actions of a higher priority. The Arctic grayling will be classified as a candidate species until a listing proposal can be prepared.  Candidate species do not receive statutory protection under the ESA and remain state-managed species.

Upper Missouri River native populations of Arctic grayling are found in the Big Hole River, Miner Lake, Mussigbrod Lake, the Madison River-Ennis Reservoir, and Red Rock lakes.

In 2007, the Service determined the fluvial Arctic grayling population of the upper Missouri River was not a listable entity under the ESA because it did not constitute a species, subspecies or Distinct Population Segment (DPS).  A DPS is a segment of a vertebrate species that is discreet or isolated from rest of the population and is considered significant to the taxon to which it belongs.

Subsequently, the Center for Biological Diversity and others filed a complaint challenging the 2007 finding.  In a settlement agreement, the Service agreed to publish a new status review finding on or before August 30, 2010.  As part of the settlement, the Service agreed to consider the appropriateness of a DPS designation for Arctic grayling populations in the upper Missouri River basin. 

Since the 2007 finding, additional research has been conducted and new information on the genetics of Arctic grayling has become available.  Today’s finding incorporates this new information resulting in a more comprehensive DPS analysis.  The results of this analysis indicate the upper Missouri River basin population of Arctic grayling satisfies the discreteness standard of the DPS policy.  This population segment is physically isolated and new genetic data provide conclusive evidence that Arctic grayling in the upper Missouri River basin have been separated from other populations for thousands of years.  Loss of this segment would create a significant gap in the species’ range.

From a practical management and conservation perspective, the Service decided that both fluvial (fish that live within a stream or river), and adfluvial (fish that live in lakes and migrate into streams to spawn) populations of Arctic grayling would be considered a single DPS.

The single DPS proposed by the Service includes only remnant native populations, of which there are currently believed to be five.  The DPS does not include introduced, naturalized populations that currently exist in lakes that did not historically contain Arctic grayling or that are outside the native range of the species in the upper Missouri River basin.  We excluded these introduced lake-dwelling populations from the DPS primarily because the intent of the ESA is to conserve native populations and genetic resources over a representative portion of a species’ historical occurrence.

The historic range of Arctic grayling in the upper Missouri River basin has declined dramatically in the past century.  The five remaining indigenous populations are isolated from one another by dams or other factors.  Most populations face threats that result from the alteration of their habitats, such as habitat fragmentation from large dams or smaller irrigation diversion structures, water withdrawals, high summer water temperatures, loss of riparian habitats, and entrainment in irrigation ditches.  At least three populations (Big Hole River, Madison River-Ennis Reservoir, Red Rock lakes) face threats from competition with and predation by nonnative trout species; and these same three populations are at low abundance and show evidence of population declines in recent decades.

Severe drought likely affects all populations, but the effects of drought are most pronounced for populations residing primarily in streams and rivers (Big Hole River) or shallow lakes (Madison River-Ennis Reservoir, Red Rock lakes).

The Service does not consider climate change in and of itself to be a significant current threat, but if current climate change projections are realized, climate change will influence the severity and scope of other threats. 

The lack of existing regulations to adequately conserve Arctic grayling populations is likely a secondary threat.
In the Big Hole River, ongoing implementation of a conservation program with substantial participation from private landowners and State and Federal partners should significantly reduce many of the habitat-related threats to that population in the foreseeable future.  At Red Rock Lakes National Wildlife Refuge, the implementation of the refuge’s comprehensive conservation plan should reduce many of the primary threats to Arctic grayling that occur within the refuge.

The Arctic grayling (Thymallus arcticus) is a freshwater fish in the same family (Salmonidae) as salmon, trout, and whitefish.  A distinctive morphological characteristic of this fish is its large, sail-like dorsal fin.  Arctic grayling is an obligate cool- or cold-water species.  Individual fish can range widely, moving tens of miles on a seasonal or annual basis between spawning, rearing, and sheltering habitats.  Arctic grayling are native to drainages of the Arctic Ocean, Hudson Bay and northern Pacific Ocean in North America and Asia.  Two distinct populations historically inhabited waters in Michigan and Montana. 

This finding will be published in the Federal Register on September 8, 2010.  More information concerning Arctic grayling is available on the Service’s web site at:

The U.S. Fish and Wildlife Service is the principal Federal agency responsible for conserving, protecting and enhancing fish, wildlife and plants and their habitats for the continuing benefit of the American people.  The Service manages the 97-million-acre National Wildlife Refuge System, which encompasses 547 national wildlife refuges, thousands of small wetlands and other special management areas.  It also operates 69 national fish hatcheries, 64 fishery resources offices, and 81 ecological services field stations.  The agency enforces Federal wildlife laws, administers the Endangered Species Act, manages migratory bird populations, restores nationally significant fisheries, conserves and restores wildlife habitat such as wetlands, and helps foreign and Native American tribal governments with their conservation efforts.  It also oversees the Federal Assistance program, which distributes hundreds of millions of dollars in excise taxes on fishing and hunting equipment to state fish and wildlife agencies.