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Status Review for Klamath Mountains Province SteelheadPeggy J. Busby, Thomas C. Wainwright, and Robin S. WaplesNational Marine Fisheries ServiceNorthwest Fisheries Science Center Coast Zone and Estuarine Studies Division 2725 Montlake Blvd. E. Seattle WA 98112-2097 December 1994 U.S. DEPARTMENT OF COMMERCE Ronald H. Brown, Secretary
National Oceanic and Atmospheric Administration
National Marine Fisheries Service |
The Endangered Species Act (ESA) allows listing of "distinct population segments" of vertebrates as well as named species and subspecies. The policy of the National Marine Fisheries Service (NMFS) on this issue for Pacific salmon and steelhead is that a population will be considered "distinct" for purposes of the ESA if it represents an Evolutionarily Significant Unit (ESU) of the species as a whole. To be considered an ESU, a population or group of populations must 1) be substantially reproductively isolated from other populations, and 2) contribute substantially to ecological/genetic diversity of the biological species. Once an ESU is identified, a variety of factors related to population abundance are considered in determining whether a listing is warranted. NMFS received a petition in May 1992 asking that winter steelhead of Oregon's Illinois River be listed as a threatened or endangered species under the ESA. In May 1993, NMFS published a Federal Register notice concluding that Illinois River winter steelhead did not by themselves constitute a species as defined by the Endangered Species Act (ESA). At the same time, NMFS indicated that it would undertake a broader status review to determine the boundaries of the Evolutionarily Significant Unit (ESU) that contains Illinois River winter steelhead and determine whether this broader group was threatened or endangered. This report summarizes biological and environmental information gathered in that status review
Based on genetic, life history, zoogeographic, geologic, and environmental information, we conclude that the ESU that contains Illinois River winter steelhead extends from the vicinity of Cape Blanco in southern Oregon to the Klamath River Basin (inclusive) in northern California. These are essentially the boundaries of a prominent geologic feature known as the Klamath Mountains Province. Both winter- and summer-run steelhead are included in this ESU, as well as populations sometimes referred to as "fall-run" in California. Within this geographic area, most steelhead populations show a declining trend in abundance, and 10 stocks have been identified in independent stock assessment reports as being at moderate or high risk of extinction. Furthermore, the declines are even more dramatic when only natural fish (progeny of naturally spawning fish) are considered. We conclude that steelhead within this ESU are likely to become endangered in the foreseeable future.
This review was conducted, in effect, as a continuation of the status review for Illinois River winter steelhead (Busby et al. 1993). Although the legal requirements for responding to the Illinois River winter steelhead petition were fulfilled by the initial status review, which concluded that the petitioned population was not a "species" under the Endangered Species Act, the National Marine Fisheries Service Directorate initiated this extended status review, and the authors of this Technical Memorandum would like to acknowledge their support.
As with all ESA status reviews, information submitted by agencies, organizations, and individuals was invaluable. The authors acknowledge the efforts of all who contributed to the Administrative Record.
The biological review team for this status review included: Peggy Busby, Dr. David Damkaer, Robert Emmett, Dr. Stephen Grabowski, Dr. Jeffrey Hard, Dr. Orlay Johnson, Dr. Conrad Mahnken, Gene Matthews, Dr. Michael Schiewe, Dr. Thomas Wainwright, William Waknitz, Dr. Robin Waples, Laurie Weitkamp, Dr. John Williams, and Dr. Gary Winans.
In May 1992, the National Marine Fisheries Service (NMFS) received a petition (ONRC et al. 1992) to list southwest Oregon's Illinois River winter steelhead (Oncorhynchus mykiss) as a threatened or endangered "species" under the U.S. Endangered Species Act (ESA) of 1973 as amended (U.S.C. 1531 et seq.). A status review completed in May 1993 (Busby et al. 1993, NMFS 1993) concluded that winter steelhead of the Illinois River, a tributary to the Rogue River (Fig. 1), did not by itself constitute a species under the ESA. However, it was also concluded that steelhead from the Illinois River are part of a larger Evolutionarily Significant Unit (ESU) whose boundaries remained to be determined. Whether the larger ESU that contains Illinois River winter steelhead would merit protection under the ESA could not be determined until the nature and extent of the ESU were identified and additional information about patterns of abundance in coastal steelhead was compiled.
On 20 May 1993, NMFS published a Federal Register notice (NMFS 1993) initiating a status review of coastal steelhead populations in California, Oregon, and Washington for the purpose of identifying ESU(s) in these areas and determining whether listing under the ESA was warranted for any identified ESU. The present report summarizes information considered in this status review relative to the ESU that includes Illinois River winter steelhead.
The biological species Oncorhynchus mykiss includes
several forms of nonanadromous
and anadromous trout, including rainbow trout, redband trout, and
steelhead (the name applied
to the anadromous form of the species). Taxonomy of O.
mykiss, and the relationship between
the various forms, has been well studied, yet remains challenging
(e.g., Kendall 1920, Snyder
1940, Behnke 1992). Behnke (1992) proposed that there are seven or
eight subspecies within
O. mykiss (Table 1).
Figure 1. Map showing the Illinois River and other key geographic
locations discussed in this
status review. See Figure 2 for detail.
Scientific name | Common name and comments |
---|---|
Rainbow trout of coastal basins | |
O. mykiss irideus |
Coastal rainbow trout from Alaska to California (anadromous form is called steelhead) |
O. mykiss mykiss |
Kamchatka rainbow trout or mikizha (anadromous form is called steelhead) |
Redband trout of northern inland basins | |
O. mykiss gairdneri |
Columbia redband trout of the Columbia and Fraser River Basins east of the Cascades, including Kamloops trout (anadromous form is called steelhead) |
Redband trout of eastern Oregon basins | |
O. mykiss newberrii |
Upper Klamath redband trout (including Upper Klamath Lake) |
(no name given) |
Oregon desert basin redband trout (other than Upper Klamath Lake) |
Redband trout of the Sacramento Basin | |
O. mykiss aguabonita |
California golden trout |
O. mykiss gilberti |
Kern and Little Kern River golden trout |
O. mykiss stonei |
Sacramento redband trout (McCloud River subspecies) |
Two major genetic groups of O. mykiss are presently recognized: the inland and coastal groups, separated by the Cascade crest (Huzyk and Tsuyuki 1974, Allendorf 1975, Utter and Allendorf 1977, Okazaki 1984, Parkinson 1984, Schreck et al. 1986, Reisenbichler et al. 1992). Both inland and coastal steelhead occur in British Columbia, Washington, and Oregon; Idaho has only inland steelhead; California has only coastal steelhead. Based on Schreck et al. (1986), the demarcation between coastal and inland steelhead in the Columbia River Basin occurs between the Hood River and Fifteenmile Creek in Oregon and between the Klickitat River and Rock Creek in Washington (i.e., in the vicinity of The Dalles Dam). These genetic groups apply to both anadromous and nonanadromous forms of O. mykiss; that is, rainbow (redband) trout east of the Cascades are genetically more similar to steelhead from east of the Cascades than they are to rainbow trout west of the Cascades. Behnke's (1992) terminology for subspecies of O. mykiss reflects this genetic difference. Coastal rainbow trout of North America, as well as coastal steelhead, are placed in the subspecies O. m. irideus (Behnke 1992). The inland Columbia redband trout of the Columbia and Fraser River Basins, as well as inland steelhead, are placed in the subspecies O. m. gairdneri (Behnke 1992). Illinois River winter steelhead fall within the coastal group, subspecies O. m. irideus.
Present distribution of coastal steelhead in Washington, Oregon, and California extends from the U.S.-Canada border south to Malibu Creek, California. Within this distribution are two major life-history types: summer-run (summer steelhead) and winter-run (winter steelhead). These run-types are primarily differentiated by time and duration of spawning migration and state of sexual maturity at the time of river entry. Summer steelhead enter fresh water between May and October, in a sexually immature condition. After several months in fresh water, summer steelhead mature and spawn. Winter steelhead enter fresh water between November and April with well-developed gonads and spawn shortly thereafter. Both summer and winter steelhead are found in some drainages, including the Rogue River Basin of southwest Oregon. The Illinois River is generally considered to have only winter-run steelhead.
The environmental and biological information developed in the Illinois River winter steelhead status review (Busby et al. 1993) indicated that the ESU that contains that population might extend somewhat north of the Rogue River Basin and south into northern California. Therefore, the present status review concentrates on environmental and biological information for that geographic area.
Two key questions must be addressed in determining whether a listing under the ESA is warranted:
1) Is the entity in question a "species" as defined by the ESA?2) If so, is the "species" threatened or endangered?
As amended in 1978, the ESA allows listing of "distinct population segments" of vertebrates as well as named species and subspecies. However, the ESA provided no specific guidance for determining what constitutes a distinct population, and the resulting ambiguity led to the use of a variety of criteria in listing decisions over the past decade. To clarify the issue for Pacific salmon, NMFS published a policy describing how the agency will apply the definition of "species" in the ESA to anadromous salmonid species, including sea-run cutthroat trout and steelhead (NMFS 1991). A more detailed description of this topic appeared in the NMFS "Definition of Species" paper (Waples 1991). The NMFS policy stipulates that a salmon population (or group of populations) will be considered "distinct" for purposes of the ESA if it represents an evolutionarily significant unit (ESU) of the biological species. An ESU is defined as a population that 1) is substantially reproductively isolated from conspecific populations and 2) represents an important component in the evolutionary legacy of the species. Information that can be useful in determining the degree of reproductive isolation includes incidence of straying, rates of recolonization, degree of genetic differentiation, and the existence of barriers to migration. Insight into evolutionary significance can be provided by data on genetic and life-history characteristics, habitat differences, and the effects of stock transfers or supplementation efforts.
Because artificial propagation of Pacific salmonids has been widespread for many years, the influence of hatchery fish needs to be considered in most ESA status reviews. NMFS policy stipulates that in determining whether a population is distinct for purposes of the ESA, attention should focus on "natural" fish, which are defined as the progeny of naturally spawning fish (Waples 1991). This approach directs attention to fish that spend their entire life cycle in natural habitat and is consistent with the mandate of the ESA to conserve threatened and endangered species in their native ecosystems. Implicit in this approach is the recognition that fish hatcheries are not a substitute for natural ecosystems.
The decision to focus on natural fish is based entirely on ecosystem considerations; the question of the relative merits of hatchery vs. natural fish is a separate issue. Fish are not excluded from ESA consideration simply because some of their direct ancestors may have spent time in a fish hatchery, nor does identifying a group of fish as "natural" as defined here automatically mean that they are part of a listed ESU. For a discussion of artificial propagation of Pacific salmon under the ESA, see Hard et al. (1992).
The ESA (sec. 3) defines the term "endangered species" as "any species which is in danger of extinction throughout all or a significant portion of its range." The term "threatened species" is defined as "any species which is likely to become an endangered species within the foreseeable future throughout all or a significant portion of its range." Neither NMFS nor the U.S. Fish and Wildlife Service (USFWS), which share authority for administering the ESA, has an official policy interpreting these definitions in terms of thresholds for considering ESA "species" as threatened or endangered. An information document on this topic (Thompson 1991) published by NMFS suggests that conventional rules of thumb, analytical approaches, and simulations may all be useful in making this determination. There is considerable interest in incorporating the concepts of population viability analysis (PVA) into ESA threshold considerations for Pacific salmon. However, available PVA models generally require substantial life-history information that is not available for most Pacific salmon populations, so quantitative PVA is not practical at this time.
Therefore, NMFS considers a variety of information in evaluating the level of risk faced by an ESU. Important factors include 1) absolute numbers of fish and their spatial and temporal distribution; 2) current abundance in relation to historical abundance and carrying capacity of the habitat; 3) trends in abundance, based on indices such as dam or redd counts or on estimates of spawner-recruit ratios; 4) natural and human-influenced factors that cause variability in survival and abundance; 5) possible threats to genetic integrity (e.g., selective fisheries and interactions between hatchery and natural fish); and 6) recent events (e.g., a drought or a change in management) that have predictable short-term consequences for abundance of the ESU.
In evaluating these factors, the role of artificial propagation is an important issue. Because of the ESA's emphasis on conserving species in their native ecosystems, threshold determinations must focus on the status of natural fish.
Artificial production may have direct or indirect impacts on the status of a population through direct supplementation of numbers, by altering the genetic composition of the population, or through ecological interactions (competition, predation, disease transmission, etc.) between artificially-produced and natural fish. A mixture of artificially-produced and natural fish in a population also makes assessment of the natural fish difficult: abundance and viability of the natural stock is difficult to estimate unless artificially-produced fish are clearly marked, and trends in the natural stock can be obscured by the infusion of artificially-produced fish and their progeny into the natural population. An important question for many natural populations is the following: Is natural production sufficient to maintain the population without the constant infusion of artificially-produced fish?
According to the ESA, the determination whether a species is threatened or endangered should be made on the basis of the best scientific information available regarding its current status, after taking into consideration conservation measures that are proposed or are in place. In this review, we did not evaluate likely or possible effects of conservation measures. Therefore, we do not make recommendations as to whether identified ESUs should be listed as threatened or endangered species, because that determination requires evaluation of factors not considered by us. Rather, we have drawn scientific conclusions about the risk of extinction faced by identified ESUs under the assumption that present conditions will continue (recognizing, of course, that natural demographic and environmental variability is an inherent feature of "present conditions").
In this section, we summarize biological and environmental information that is relevant to determining the nature and extent of the ESU that includes Illinois River winter steelhead. Information presented in this section forms the basis for conclusions regarding the species and threshold questions, which are addressed in the following section.
Ecoregions and Zoogeography
Many efforts have been made to describe and classify the distributions of the Earth's plant and animal species and their habitats. These have resulted in the development of several classification schemes for continental and marine environments.
Bailey (1976, 1980), Omernik and Gallant (1986), and Omernik (1987) used geologic, edaphic, climatic, and vegetational patterns to delineate ecoregions for the United States. Franklin and Dyrness (1973) used similar information to delineate physiographic provinces for Oregon and Washington. Most recently, the Forest Ecosystem Management Assessment Team (FEMAT) delineated aquatic and terrestrial physiographic provinces for the northern spotted owl region (USFS and BLM 1994).
Zoogeographic regions and provinces in the marine environment have been described using climate and faunal distribution. Allen and Smith (1988) discussed the marine zoogeographic literature and presented zoogeographic regions and provinces and marine life zones for the North Pacific Ocean and Bering Sea. Within the Oregonian Province, Allen and Smith (1988, p. 144) found that Cape Mendocino, California "is an important southern limit (at least in abundance) of many northern species" of marine fish.
Ichthyogeography--Snyder (1907) may have been the first to attempt to categorize the freshwater ichthyofauna of Oregon and California into geographic groups. Based on phenotypic characteristics and assemblages of fluvial fish species, Snyder (1907) identified three ichthyofaunal groups for the coastal area between the Columbia and Sacramento Rivers: Columbia River Fauna, Klamath River Fauna, and Sacramento River Fauna. The Columbia River faunal group included basins north of the Rogue River. The Klamath River faunal group included the Rogue and Klamath River Basins. The Sacramento River faunal group included rivers south of the Klamath Basin.
Moyle (1976) discussed the zoogeography of inland fish of California. He noted that the Klamath smallscale sucker (Catostomus rimiculus) is common to both the Rogue and Klamath Rivers, yet the Rogue River "lacks other Klamath fishes, such as speckled dace [Rhinichthys osculus] and marbled sculpin [Cottus klamathensis], and contains reticulate sculpin [C. perplexus], a species abundant in coastal streams further north" (Moyle 1976, p. 15). Moyle considered coastal streams of northern California (south of the Klamath River) to be part of the Sacramento River inland fish fauna, as did Snyder (1907). Moyle specifically noted that "the Mad, Eel, Bear, Navarro, Gualala, and Russian rivers, as well as three tributaries to Tomales Bay (Walker, Papermill, and Olema creeks) all contain freshwater fishes derived from the Sacramento-San Joaquin River system" (p. 17).
Hughes et al. (1987) described ichthyogeographic regions in Oregon based on the distribution of 68 native fish species. They found a similarity between these ichthyogeographic regions and the physiographic provinces of Franklin and Dyrness (1973) and the aquatic ecoregions of Omernik (1987). Hughes et al. concluded that seven ichthyogeographic regions could be delineated in Oregon. Coastal steelhead are known from all of these regions except the Blue Mountains region, which contains inland steelhead, and the Endorheic Lakes region of eastern Oregon, which contains redband trout.
Physiographic and zoogeographic classification of southwest Oregon--With respect to the above, the Illinois River (Rogue River Basin) of southwest Oregon falls within the Coast Range and Sierra Nevada ecoregions of Omernik (1987) and the Klamath Mountains physiographic region of Franklin and Dyrness (1973) and FEMAT (USFS and BLM 1994). The Rogue River Basin is within the Rogue River/Sierra Nevada ichthyogeographic region of Hughes et al. (1987) and the Klamath/Siskiyou and Franciscan aquatic ecosystems physiographic provinces of FEMAT (USFS and BLM 1994). The Rogue River Basin shares some inland ichthyofaunal commonalities with the Klamath River to the south, as well as with some streams to the north (Snyder 1907, Moyle 1976, Behnke 1992). Each of the studies cited above has consistently delineated an ecoregion, that includes the Illinois River, that largely corresponds with a geological feature known as the Klamath Mountains Geological Province.
Klamath Mountains Geological Province
The Klamath Mountains Geological Province includes a complex of mountain ranges in southwest Oregon and northwest California (Fig. 2). Collectively, these are called the Klamath Mountains; they include the Trinity Alps, Salmon Mountains, Marble Mountains, and Siskiyou Mountains (Wallace 1983). Ecologically, the region is classified in the Marine Division of the Humid Temperate Domain (Bailey 1980); however, it exhibits influence from the warmer, drier Mediterranean Division (Atzet - footnote 1). This region includes diverse localized climates including cool, wet coastal areas and hot, dry interior valleys that receive less precipitation than any other location in the Pacific Northwest west of the Cascade Range (Franklin and Dyrness 1973). For example, average annual precipitation in the interior Rogue River valley ranges between 30 and 94 cm (Oregon Water Resources Committee 1955), while at Cave Junction in the middle Illinois Valley it is 152 cm, and Gold Beach at the mouth of the Rogue River receives 229 cm (USFS 1989).
The Siskiyou Mountains include northern extensions of geological formations typical of those found in the California Coast Ranges and the Sierra Nevada (Franklin and Dyrness 1973). The unusual geology and climate result in vegetation which "combines elements of the California, north coast, and eastern Oregon floras, with a large number of species indigenous only to the Klamath Mountains region" (Franklin and Dyrness 1973, p. 130).
Figure 2. Map of the southern Oregon-northern California area.
Shaded area is the Klamath
Mountains Geologic Province (modified from Irwin 1966 and Walker and
MacLeod 1991).
The rivers and streams of California, Oregon, and Washington drain into the California Current system of the eastern North Pacific Ocean. This current system includes the California Current, the California Undercurrent, and the Davidson Current (Hickey 1989). The prevailing California Current has a southerly flow. The California Undercurrent (or Countercurrent) flows northward on the continental slope. Both the California Current and California Undercurrent are strongest in summer (Hickey 1989). The Davidson Current is a north-flowing seasonal surface current, existing in winter and early spring (Doyle 1992).
Upwelling--Upwelling occurs when warm, nutrient poor surface waters are driven offshore by wind stress and are replaced by cold, nutrient-rich subsurface water. On the Oregon coast, prevailing winds from September through March are from the southwest. At the end of March, wind direction shifts, typically coming from the northwest, and Ekman transport causes surface water to move offshore and deep water moves up to replace it (Ingmanson and Wallace 1973, Neshyba 1987). These wind patterns result in summer upwelling and winter downwelling.
The strength and consistency of upwelling south of Cape Blanco yields highly productive waters. This is demonstrated in satellite imagery, described by Pearcy (1992), that shows chlorophyll-rich water extending several hundred kilometers offshore south of Cape Blanco to approximately 33øN latitude (Thomas and Strub 1989).
Data from the U.S. Geological Survey for coastal streams in Oregon and northern California demonstrate that with decreasing latitude there is an upward trend in water temperature (Table 2). There appears to be a geographical break-point in the average high water temperature south of the Mad River, California.
Stream |
Recording location |
Month (January-June) |
Month (July-December) |
Year* |
Years of record |
Number of years recorded |
---|---|---|---|---|---|---|
Oregon | ||||||
Siuslaw River | Mapleton | Jan: 6.7
Feb: 7.5 Mar: 8.9 Apr: 10.5 May:14.8 Jun: 18.8 |
Jul: 22.5
Aug: 22.6 Sep: 18.7 Oct: 13.5 Nov: 9.1 Dec: 7.5 |
13.4 | 1970-82 | 11 |
Umpqua River | Elkton | Jan: 5.9
Feb: 6.9 Mar: 9.0 Apr: 11.6 May: 15.6 Jun: 19.9 |
Jul: 23.7
Aug: 23.4 Sep: 19.9 Oct: 14.4 Nov: 9.1 Dec: 6.3 |
13.8 | 1971-91 | 21 |
Rogue River | Agness | Jan: 5.9
Feb: 7.2 Mar: 8.8 Apr: 11.2 May: 15.1 Jun: 19.4 |
Jul: 22.7
Aug: 22.3 Sep: 18.7 Oct: 13.5 Nov: 9.0 Dec: 6.7 |
13.4 | 1961-88 | 28 |
California | ||||||
Smith River | Crescent City | Jan: 7.5
Feb: 8.2 Mar: 9.0 Apr: 10.6 May: 13.7 Jun: 17.6 |
Jul: 20.4
Aug: 20.4 Sep: 17.9 Oct: 13.6 Nov: 10.2 Dec: 8.0 |
13.1 | 1966-81 | 16 |
Klamath River | Klamath | Jan: 6.8
Feb: 7.7 Mar: 9.0 Apr: 11.5 May: 14.4 Jun: 18.6 |
Jul: 22.4
Aug: 22.2 Sep: 20.1 Oct: 16.2 Nov: 11.4 Dec: 7.5 |
14.0 | 1966-81 | 16 |
Redwood Creek | Orick | Jan: 7.5
Feb: 8.8 Mar: 9.6 Apr: 11.6 May: 15.8 Jun: 20.5 |
Jul: 22.2
Aug: 21.4 Sep: 19.6 Oct: 14.9 Nov: 9.9 Dec: 8.1 |
14.2 | 1966-79 | 14 |
Mad River | Arcata | Jan: 7.8
Feb: 9.3 Mar: 10.2 Apr: 12.6 May: 16.2 Jun: 18.8 |
Jul: 21.5
Aug: 21.2 Sep: 19.6 Oct: 16.0 Nov: 11.6 Dec: 8.7 |
14.5 | 1962-79 | 16 |
Eel River | Scotia | Jan: 8.2
Feb: 9.0 Mar: 10.5 Apr: 12.8 May:16.8 Jun: 19.9 |
Jul: 21.7
Aug: 21.6 Sep: 20.5 Oct: 16.9 Nov: 12.5 Dec: 9.1 |
15.0 | 1962-82 | 20 |
Mattole River | Petrolia | Jan: 8.7
Feb: 10.0 Mar: 11.7 Apr: 14.0 May: 17.8 Jun: 22.1 |
Jul: 23.4
Aug: 22.5 Sep: 21.1 Oct: 16.7 Nov: 12.3 Dec: 9.9 |
15.9 | 1966-79 | 13 |
Noyo River | Fort Bragg | Jan: 8.5
Feb: 9.6 Mar: 10.8 Apr: 12.8 May: 16.4 Jun: 18.8 |
Jul: 20.3
Aug: 19.8 Sep: 18.3 Oct: 14.2 Nov: 11.2 Dec: 8.9 |
14.1 | 1966-79 | 14 |
Navarro River | Navarro | Jan: 8.7
Feb: 10.1 Mar: 11.7 Apr: 13.8 May: 18.4 Jun: 21.5 |
Jul: 22.4
Aug: 21.7 Sep: 20.0 Oct: 16.2 Nov: 11.9 Dec: 8.9 |
15.4 | 1966-79 | 13 |
Garcia River | Point Arena | Jan: 10.6
Feb: 11.4 Mar: 12.6 Apr: 14.5 May: 17.1 Jun: 18.7 |
Jul: 19.6
Aug: 19.6 Sep: 18.8 Oct: 16.7 Nov: 13.6 Dec: 11.2 |
15.4 | 1964-79 | 16 |
Russian River | Guerneville | Jan: 9.9
Feb: 11.6 Mar: 13.3 Apr: 16.2 May: 20.3 Jun: 23.6 |
Jul: 25.6
Aug: 24.6 Sep: 22.3 Oct: 18.2 Nov: 13.6 Dec: 10.3 |
17.5 | 1964-82 | 19 |