|Scientific Name:||Oregonichthys crameri|
|Species Authority:||(Snyder, 1908)|
Hybopsis crameri Snyder, 1908
|Red List Category & Criteria:||Least Concern ver 3.1|
|Reviewer(s):||Smith, K. & Darwall, W.R.T.|
|Facilitator/Compiler(s):||Hammerson, G.A. & Ormes, M.|
This species is downlisted from its previous assessment of VU (in 1996). The population experienced a severe decline in the 1950s and 1960s after the completion of flood control projects, resulting in its disappearance from most of its range. Since then, its status has improved. Currently most of its populations are stable or increasing. The species still has a somewhat small extent of occurrence, but it is now listed as Least Concern in view of the large number of subpopulations and locations, fairly large population size, and increasing trend in distribution and abundance.
|Range Description:||Range includes portions of the Willamette River system of the Columbia River drainage in western Oregon (see map in Scheerer 2002, Page and Burr 2011). In the early 1990s, populations were found predominantly in the Middle Fork Willamette River (Middle Fork), with a few, small populations found in the mid-Willamette River, Santiam River, and Coast Fork Willamette River (Coast Fork). The species is now well distributed throughout the Willamette Basin (in Polk, Marion, Linn, Lane, and Benton counties, Oregon), with populations in the Santiam River (nine sites), Mid-Willamette River (six sites), McKenzie River (four sites), Middle Fork (16 sites), and Coast Fork (three sites) (see USFWS 2010).|
|Range Map:||Click here to open the map viewer and explore range.|
Scheerer (2002) mapped 17–18 sites where this species was collected during 1991-2000; these represented at least a half dozen distinct occurrences; well over 100 sites in the Willamette Valley did not yield any Oregon chubs.
Currently, there are 38 populations, of which 19 contain more than 500 adults each (see USFWS 2010).
Total adult population size exceeds 100,000 (see USFWS 2010).
At one point, this species had disappeared from most (98%) of the historical range; it experienced a severe decline in the 1950s and 1960s after completion of flood control projects in the Willamette River Basin. Subsequently, status has improved; species is now relatively abundant and well distributed throughout much of its presumed historical range (USFWS 2010).
Sixteen of the 19 current populations have a stable or increasing trend (see USFWS 2010). Three generations span approximately 10–15 years.
|Habitat and Ecology:||
This is a floodplain species. Preferred habitat is slow-moving pools, sloughs, backwaters, ponds, and reservoirs; often associated with aquatic vegetation (30-70% cover) and depositional substrates; occupied streams may be covered by thin ice in winter (Lee et al. 1980, Markle et al. 1991, Page and Burr 2011).
Spawning occurs over plants in still water; spawners formerly may have been carried to pond and slough breeding habitats during winter and spring flooding (Markle et al. 1991). Males defend territories in or near aquatic vegetation such as Fontinalis (see USFWS 1993).
The decline possibly was due to the effects of dam construction, flood control structures, and/or introduced fishes (Markle et al. 1991, USFWS 1993). In the early 1990s, most remaining populations occurred near rail, highway, and power transmission corridors and within public park and campground facilities; these populations were threatened by (1) direct mortality from potential chemical spills and overflow from chemical toilets in campgrounds, (2) competition with and predation by non-native fishes (e.g., bass, crappie, mosquitofish) (Scheerer 2002), and (3) loss of habitat from siltation caused by logging and construction activities, unauthorized fill activities, and changes in water level or flow conditions from construction, diversions, or natural desiccation (USFWS 1993). This species does best in habitats isolated from non-native fishes; increased connectivity of floodplain habitats in a system where non-native fishes are widespread may be detrimental to the conservation and recovery of this species (Scheerer 2002).
Threats to existing habitats include manipulation of flows (can lead to desiccation), nutrient and pesticide runoff, and vegetative succession in shallow pond environments. The chief threat to existing populations is invasion by non-native fishes, which may occur as a result of flood events, intentional introductions, or through connections between isolated chub habitats and adjacent watercourses. However, the status of the species has improved since listing (i.e., more populations have been established and are being managed to minimize threats), so the relative effect of the threat of predatory non-native fishes has declined. Monitoring for non-native fish invasions and adaptively managing in response to such invasions is necessary for the long-term viability of this species. Source: USFWS (2010).
|Conservation Actions:||Currently, this species is of relatively low conservation concern and does not require significant additional protection or major management, monitoring, or research actions.|
|Citation:||NatureServe 2013. Oregonichthys crameri. The IUCN Red List of Threatened Species. Version 2015.2. <www.iucnredlist.org>. Downloaded on 04 August 2015.|
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