Sturgeon Chub - Macrhybopsis gelida
The sturgeon chub is one of several native minnows found in the eastern MT prairie river drainages (Missouri, lower Yellowstone and Powder Rivers) and is an indicator species of the Large Mainstem Warmwater River Fish Assemblage that includes other big river species--the sicklefin chub, shovelnose sturgeon, freshwater drum and blue sucker. This fish is so named because its mouth is ventral and its snout is long and overhangs the mouth, somewhat like the snout of the sturgeon. Sturgeon chubs have been rarely collected in the past and were placed as a candidate on the Endangered Species list in 1994, but were removed from consideration in 2001 with more collection efforts. They are a Fish Species of Special Concern in Montana (and 9 other states) due to extensive loss of habitat in the Missouri and Bighorn River systems. They are typically found in the rapid, gravelly turbid waters in larger, plains rivers. They are benthic invertivores using their ventral mouth to feed on bottom-dwelling insects; a short intestine also indicates they do not consume plant materials to a large degree. Sturgeon chubs attain a maximum length of about 4 inches and spawn over gravels in June to July.
Sturgeon chub have small eyes and many external papillae on their bodies and fins, probably to aid in locating food (Cross 1967, Pflieger 1975) (Montana AFS Species Status Account
The back is brownish to blueish, and the sides and underparts are silvery to white. The overhanging snout on their ventral mouth is the classic characteristic and there is a conspicuous barbel at each corner of the mouth.
Summary of Observations Submitted for Montana
Number of Observations:
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(Records associated with a range of dates are excluded from time charts)
Sturgeon chub are found in turbid water with moderate to strong current over bottoms ranging from rocks and gravel to coarse sand (Brown 1971, Holton 1980).
In the Powder River, sturgeon chub were taken most frequently at sites with depths less than 51 centimeters and depth velocities of less than 90 centimeters per second at 0.6 depth (Stewart 1981, Werdon 1992, Gould unpublished data) (Montana AFS Species Status Account
A Powder River, Wyoming study showed sturgeon chub to feed mostly on small invertebrates living on the bottom substrate (Stewart 1980).
Sturgeon chub are often found with longnose dace (Morris 1981). Young of the year may be associated with a sand bottom. Dam building disrupts required habitat (Stewart 1980).
Average lengths at ages 1 through 3 were calculated to be 48, 69 and 80 millimeters respectively (Werdon 1992). Apparently few fish reach age 4 (Stewart 1981) (Montana AFS Species Status Account
The biology of sturgeon chub is not well known. It apparently spawns from June through July (Lee et al. 1980, Stewart 1981, Werdon 1992, Gould 1994). Ripe fish have been found in waters of about 18 to 25 degrees C. (Cross 1967, Werdon 1992, Gould 1994). Sexual maturity is obtained by age 2 at sizes of about 76 millimeters total length (Stewart 1981, Werdon 1992) (Montana AFS Species Status Account
). Females produce 2000 to 3500 eggs (Stewart 1980).
The management of this species should involve routine monitoring (once every 2 to 3 years) of existing populations. The monitoring program should be designed to evaluate population trends, range expansion or losses and collect additional information on life history and ecology. This could be conducted while sampling for other species. Recommendations for operating reservoir and irrigation projects should be developed for improving and maintaining sturgeon chub populations and habitats in Montana. Reintroduction of sturgeon chub should be considered for the lower Teton, Milk and Tongue rivers (AFS website 2010).
Threats or Limiting Factors
Major threats to the sturgeon chub and other large river fishes are habitat and flow alterations from dams, diversions, irrigation operations and riparian development (Rinne et al. 2005). Sturgeon chubs need gravel riffles and runs in turbid shallow and deeper running waters for their life history requirements (Werdon 1992), thus decreased flows and excessive siltation of gravels are threats facing all lithophilic spawning fish species (Waters 1995). Reservoirs created behind dams inundate riverine habitats and replace the river with lentic conditions, which is unsuitable habitat for sturgeon chubs. Dams also create unsuitable habitat for sturgeon chubs downstream by reducing turbidities and/or altering temperature and flow regimes (Ruggles, pers. comm). Fortunately for this species, it appears unlikely that any new dams will be built on the Powder, Yellowstone or Missouri rivers in Montana in the foreseeable future. However, water regulation at Fort Peck Dam and several other tributary dams (Intake on the Yellowstone) continue to limit the distribution and abundance of some fish populations in Montana by fragmenting populations and restricting spawning and migration patterns (Ruggles, pers. comm., Rinne et al. 2005).
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- Montana Chapter of the American Fisheries Society species status accounts.
- U.S. Fish and Wildlife Service (USFWS). 1993. Status report on sturgeon chub (MACRHYBOPSIS GELIDA) a candidate endangered species. Ecological Services, Bismark, North Dakota.
- Werdon, S.J. 1992. Population status and characteristics of Macrhybopsis gelida, Platygobio gracilis and Rhinichthys cataractae in the Missouri River Basin. South Dakota State University, Brookings, SD. M.S. Thesis, 55pp.
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