|Scientific Name:||Macrhybopsis gelida|
|Species Authority:||(Girard, 1856)|
Gobio gelidus Girard, 1856
|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 listed as Least Concern because although its habitat has been extensively altered and fragmented, and distribution and abundance of the species have declined over the long term, the remaining extent of occurrence is large, area of occupancy is more than 2,000 sq km, distribution is not severely fragmented, trend is relatively stable, and number of locations exceeds 10. Population size is unknown but presumably exceeds 10,000.
|Range Description:||Historically, the range included 14 states of the Missouri and Mississippi rivers and their larger tributaries, including approximately 2,100 miles (33,600 km) of the main stem Missouri River and about 1,150 miles (1,840 km) of the Mississippi River, plus the Yellowstone River in Montana and North Dakota and 30 tributaries to the Yellowstone and Missouri rivers (USFWS 2001). Currently this species occupies about 1,155 miles (1,850 km) (55 percent) of the historical range in the Missouri River and is extant in 11 of 30 tributaries to the Yellowstone and Missouri rivers that have suitable habitat; viable populations also exist in the middle Mississippi River and the Wolf Island area of the lower Mississippi River (USFWS 2001).
Distribution maps are included in Lee et al. (1980), USFWS (2001), and Rahel and Thel (2004).
|Range Map:||Click here to open the map viewer and explore range.|
This species is known historically known from over 190 sites. The number of distinct occurrences has not been determined using standardized criteria, but a map in USFWS (2001) indicates that extensive occurrences exist in several areas throughout the historical range.
Total population size is unknown. Recent benthic trawl surveys indicate that this species makes up a significant part of the Missouri fish fauna at three sampled locations (USFWS 2001). In many areas, this fish represents only a small percentage of the sampled fish population (Jackson 2002, Rahel and Thel 2004).
Range has declined compared to historical distribution, but use of better sampling methods (benthic trawls) indicates that the species is more common and widespread than previously believed (USFWS 2001).
USFWS (2001) estimated that the species occupies about 55 percent of its historic range in the mainstem Missouri River and has been extirpated from 19 of 30 tributaries to the Yellowstone and Missouri rivers that likely contained the species.
Trend over the past 10 years or three generations is uncertain but likely relatively stable. Three generations span not more than 10 years.
Most of the decline occurred in the mid- to late 1900s with the construction of large impoundments; remaining populations are fragmented but appear to be viable (Rahel and Thel 2004). Populations apparently are stable in distribution and abundance in Missouri (see Figg and Bessken 1995). Sturgeon Chub appears to be stable in the middle Mississippi River (Jackson 2002).
|Habitat and Ecology:||Habitat includes shallow sand and gravel runs of warm, turbid, medium to large rivers; this species colonizes tributaries when flow and turbidity are sufficient (Gould 1997, Page and Burr 2011). Sturgeon Chubs are often associated with main channels, high turbidity, moderate to strong currents over sand or fine gravel, sand/gravel bars, but they also have been found in sustained current over rock or gravel riffles; generally they occur in areas lacking vegetation or other cover; adults and young exhibit to major differences in habitat (see Rahel and Thel 2004 for literature review and further details). Spawning habitat has not been identified (Rahel and Thel 2004).|
Decline resulted mainly from human-induced changes in river conditions, particularly the development and operation of reservoirs on large rivers (Rahel and Thel 2004). Dams have flooded river habitat, altered temperature and flow regimes, reduced sediment transport and turbidity, fragmented populations, and reduced movement opportunities. By fragmenting the habitat and chub populations, dams exacerbate the loss of fish populations caused by drought, channel dewatering due to irrigation, or poor water quality (Rahel and Thel 2004). For example, extended drought may extirpate a population. and impoundments may block recolonization pathways from potential source populations in mainstem rivers (Kelch 1994). Also, existing habitat fragments may be too small to support successful spawning and development (e.g., see Bonner and Wilde 2000). When impoundments are numerous, Sturgeon Chub eggs and fry may become entrained in reservoirs and encounter heavy predation (Rahel and Thel 2004). Water diversion for irrigation potentially threatens chub populations where eggs and fry enter and become stranded in canals (Rahel and Thel 2004).
Channelization has reduced habitat diversity and reduced overbank flooding. Sand and gravel excavation have removed habitat and restricted fish movements in some areas. Dredging for channel maintenance and sand/gravel extraction will continue in new areas.
Pollution from industry and agriculture may have altered water quality. "Coalbed methane development in northeastern Wyoming and southeastern Montana poses a potential threat to sturgeon chub populations in the Powder and Tongue river basins because discharged water can have high salinity and toxic concentrations of trace elements" (Rahel and Thel 2004).
Ongoing water depletion from industry and agriculture is a concern. Further water depletion is likely to occur in the future due to energy development in the Upper Missouri River Basin, increased interbasin transfer of water, and increased municipal, industrial, and irrigation use.
Severe drought in the early 1990s may have eliminated populations in some Missouri River tributaries (Kelch 1994). Populations in the mainstem Missouri River may be too small and too widespread to naturally recolonize these tributaries even if suitable habitat is available.
This species also may be negatively impacted by the numerous species of non-native fishes that have been introduced into the habitat (USFWS 1995). These fishes flourish in dam-altered waters with reduced turbidity, and they may compete with and prey on Sturgeon Chubs (Rahel and Thel 2004). However, the degree and effect of predation on Sturgeon Chub populations are unknown. Similarly, the effects of potential non-native competitors are unknown.
Diseases are not known to pose a significant threat to the Sturgeon Chub.
"Management actions important for the conservation of sturgeon chub include restoring natural flow regimes with spring flood pulses to promote development of sandbar habitat, reconnecting side channel and floodplain habitats lost due to channelization, and restoring turbidity levels that favor sturgeon chub over nonnative predators and competitors. Given the difficulties of removing existing dams, maintaining the remaining unimpounded reaches of turbid prairie rivers in a free-flowing state should be a conservation priority. Preventing nonnative fisheries establishment within these remaining unimpounded prairie river segments is important as well. Attention also needs to be given to maintaining flows in streams that were historically perennial. Perennial flows are threatened by extraction of groundwater for agricultural and municipal uses, especially in the Ogallala-High Plains aquifer. Conversely, potentially toxic water produced from coalbed methane production may need to be tested, stored, and/or treated in some manner."
Ongoing and proposed conservation measures, such as those intended to mitigate fish and wildlife resources lost due to construction and operation of the Missouri River Bank Stabilization and Navigation Project, and those aimed at benefiting Pallid Sturgeon, are likely to have a beneficial impact on Sicklefin Chub and Sturgeon Chub populations (see USFWS 2001 and Rahel and Thel 2004 for details).
Better information is needed on movement patterns and current distribution and abundance.
|Citation:||NatureServe 2014. Macrhybopsis gelida. The IUCN Red List of Threatened Species. Version 2015.2. <www.iucnredlist.org>. Downloaded on 04 July 2015.|
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