U.S. Dept Commerce/NOAA/NMFS/NWFSC/Publications Tech Memo-15: Status Review for Oregon's Umpqua River Sea-Run Cutthroat Trout INTRODUCTIONSea-run cutthroat trout is the common name for the anadromous life-history form of coastal cutthroat trout (Oncorhynchus clarki clarki). The subspecies is found in the coastal temperate rainforests of western North America from southeast Alaska to northern California (Trotter 1989) (Fig. 1). Coastal cutthroat trout belong to the same genus as Pacific salmon and steelhead, but they are generally a smaller fish, rarely over-winter in the sea, and do not usually make long ocean migrations. Like steelhead, but unlike other Pacific salmon, cutthroat trout are iteroparous rather than semelparous, and adult cutthroat trout have been known to spawn each year for over 6 years. 
The life history of coastal cutthroat trout may be the most diverse and flexible of any Oncorhynchus species. They have adapted to a wide variety of climatological conditions, a diversity of marine and freshwater habitats, and competition with other salmonids for food and space. Populations often show differences in size and age at migration, timing of migrations, age at maturity, and frequency of repeat spawning. Although all coastal cutthroat trout populations with access to the sea are believed to have an anadromous component, not all members of the subspecies migrate to the sea (Trotter 1989, P. Trotter - footnote 1 ). Some cutthroat trout simply remain in headwater tributaries, while others migrate only within rivers or lakes.

Figure 1. Range of coastal cutthroat trout (Oncorhynchus clarki clarki) (shading on coast) and of 13 interior subspecies (O. c. subspp.) (shading inland) identified in Table 2. Framed area represents Umpqua River Basin depicted in Figure 2.

Because coastal cutthroat trout have not been as intensely studied as Pacific salmon and steelhead, and because anadromous cutthroat trout in the Umpqua River are depauperate, very little biological information is available on Umpqua River cutthroat trout life history. A description of cutthroat trout in the Umpqua River by the Oregon State Fish Commission in 1946 (FCO and OSGC 1946, p. 25) is still apt:
Very little is yet known about these fish and they have been   rightly called the "problem children" of the State Game Commission.... Since   insufficient information has been accumulated to justify making   recommendations, no changes are suggested....
This response was reflected by many state and federal resource agencies across the range of cutthroat trout. The attitude toward cutthroat trout ranged from benign neglect to outright exterminations (Behnke 1981). Perhaps most destructive was the widespread release of hatchery rainbow trout (O. mykiss) throughout the native range of interior cutthroat trout. The two species hybridize, to the extreme detriment of O. clarki, and it has been estimated that "just within the last century perhaps 99 percent of the unique cutthroat strains of interior drainages have been lost forever" (Willers 1991, p. 10). "In less than 100 years after the first [United States] settlements in the West, the cutthroat trout vanished from most of its vast range..." (Behnke 1988, p. 1). Today, of 16 recognized subspecies of cutthroat trout, 2 are extinct and 12 are given protected status by individual states; 8 of the latter are listed under the U.S. Endangered Species Act (ESA) (Behnke 1979, Johnson 1987, Allendorf and Leary 1988).

Coastal cutthroat trout are considered the healthiest of the subspecies of cutthroat trout and, across their range, have experienced the least habitat destruction, hybridization with introduced species, or over-fishing pressures (reviewed in Pauley et al. 1989, Trotter 1989, Trotter et al. 1993). Still, the Endangered Species Committee of the American Fisheries Society (AFS) identified all populations of anadromous cutthroat trout as being at some risk of extinction, and coastal cutthroat trout from all Oregon streams as being at moderate risk of extinction (Nehlsen et al. 1991, Trotter et al. 1993). Sea-run cutthroat trout populations from Hood River in Oregon and from the Wind and Klickitat Rivers in Washington were identified as extinct.

A serious impediment to the conservation and management of coastal cutthroat trout is that little information is available on population sizes or trends. Across the range of O. c. clarki there is only one location where long-term counts of migrating adult sea-run cutthroat trout have been made -- at Winchester Dam on the North Umpqua River near Roseburg, Oregon (Table 1, Fig. 2). Counts of anadromous salmonids have been made since 1946, and they revealed a dramatic decline in cutthroat trout in the late 1950s (Fig. 3). In fact, more sea-run cutthroat trout (1,138) were counted passing Winchester Dam in 1946 than have passed the dam in the last 15 years (less than 825; Loomis et al. 1993). In the winter of 1992-1993, no sea-run cutthroat trout were counted passing the dam, and only 29 were counted in the winter of 1993-1994.
Table 1. Numbers of returning adult anadromous cutthroat trout passing Winchester Dam on the North Umpqua River from 1946 to 1993, and releases of Alsea River hatchery cutthroat trout immediately below Winchester Dam from 1961 to 1976, in Smith River from 1975 to 1993, and in Scholfield Creek from 1982 to 1993 (Loomis et al. 1993). For locations, see Figure 2. YearNumber of smolts released below Winchester     DamNumber of smolts released in Smith RiverNumber of smolts released in Scholfield CreekNumber of returning adults194619471948194919501951195219531954195519561957195819591960196119621963196419651966196719681969197019711972197319741975197619771978197919801981198219831984198519861987198819891990199119921993---------------5,00010,00010,00010,00020,00020,00020,00020,00020,00019,00020,00019,00020,00020,00017,0009,000----------------------------------------------9,9007,50010,00015,10011,10012,70020,10019,1009,10015,80015,8001,2008,10011,90012,00012,00012,00012,00012,000------------------------------------2,6002,7004,5004,5004,0008,0004,0004,0004,0004,0004,0004,0001,1389744374396641,5087611,83870696098287108481063063081424207962,3642,2001,0319421,8802891,0941,7126224275441231042574861564310488533547383410029In response to this information and indications from a report of the AFS Endangered Species Committee (Nehlsen et al. 1991) that coastal cutthroat trout populations throughout their range may also be experiencing a severe decline, the Oregon Natural Resources Council, the Wilderness Society, and the Umpqua Valley Audubon Society (ONRC et al. 1993) petitioned the National Marine Fisheries Service (NMFS) to list the North and South Umpqua River sea-run cutthroat trout as a threatened or endangered species under the ESA. This report summarizes a review of the status of these fish conducted by the biological review team of NMFS Northwest Fisheries Science Center. 
Figure 2. Location map of the Umpqua River Basin on the Oregon coast (see also Figure 1).

Figure 3. Yearly counts of cutthroat trout passing Winchester Dam on the North Umpqua River from 1946 to 1993 (Loomis et al. 1993). Alsea River hatchery cutthroat trout were released into the North Umpqua River Basin immediately below Winchester Dam from 1961 to 1976.
TerminologyA difficulty in conducting a status review on a species that has received little scientific attention is that historical surveys, reports, or other scientific documents often do not differentiate sea-run cutthroat trout from other species of salmonids (especially steelhead, the sea-run form of O. mykiss), or else refer to them with a variety of confusing local names. In the literature, sea-run cutthroat trout have been most often referred to as sea-run trout, but they have also been called harvest trout, blueback, salmon trout (Roth 1937), steelhead cutthroat (Shultz 1936), and sea trout (Clemens and Wilby 1946). The freshwater or resident form of the subspecies has often been simply identified as trout, but also as native, mountain, speckled, or brook trout (Behnke 1972b, 1992). 
In this document, we will refer to the entire subspecies (all life-history forms) as coastal cutthroat trout or cutthroat trout, but when discussing only the anadromous form, we will use the term "sea-run" or "anadromous" cutthroat trout.
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