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Montana Field Guide

Montana Field Guides

Creek Chub - Semotilus atromaculatus

Potential Species of Concern

Global Rank: G5
State Rank: S4
* (see State Rank Reason below)

Agency Status
USFWS:
USFS:
BLM:


 

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State Rank Reason (see State Rank above)
The creek chub is currently ranked an S4 in Montana and is considered a potential species of concern. While this species is apparently secure, it may be quite rare in parts of its range, and/or suspected to be declining.
  • Details on Status Ranking and Review
    Creek Chub (Semotilus atromaculatus) Conservation Status Review
    Review Date = 04/08/2010
    View State Conservation Rank Criteria
    Population Size

    ScoreU - Unknown

    CommentUnknown.

    Range Extent

    ScoreF - 20,000-200,000 km squared (about 8,000-80,000 square miles)

    Comment51,809 square kilometers based on Heritage Range Map area of 64,761 square kilometers, minus an estimated 20% of this range where they are introduced or in error (Fort Peck = introduced and Redwater River = error).

    Area of Occupancy

    ScoreE - 100-500 km squared (about 25,000-125,000 acres)

    Comment171 square kilometers based on Heritage Range Maps and occupancy of 1% of landscape by streams and occupancy of 33% of sites surveyed

    Long-term Trend

    ScoreE - Relatively Stable (±25% change)

    CommentEven though they have been impacted by grazing, exotic species, and some dewatering, prairie streams have probably been pretty stable in terms of water etc. since the arrival of Europeans within +/-25%

    Short-term Trend

    ScoreE - Stable. Population, range, area occupied, and/or number or condition of occurrences unchanged or remaining within ±10% fluctuation

    CommentSince 1999, prairie fish surveys do not suggest decline as indicated by distribution data although this is not as sensitive to detecting decline as regular monitoring of a network of sites. The recent surveys have documented introductions in Fort Peck Lake.

    Threats

    ScoreF - Widespread, low-severity threat. Threat is of low severity but affects (or would affect) most or a significant portion of the population or area.

    CommentOvergrazing, road crossings, dams, and exotic species (Northern Pike in particular) all represent threats.

    SeverityLow - Low but nontrivial reduction of species population or reversible degradation or reduction of habitat in area affected, with recovery expected in 10-50 years.

    CommentSpecies is capable of recovering quickly if suitable habitat is available. Northern Pike have heavy impacts during wet periods, however may be unable to persist in high numbers due to stochastic droughts and flooding so the Creek Chub may persist with No

    ScopeModerate - 20-60% of total population or area affected

    Comment75% of Creek Chub's range overlaps with the range of Northern Pike and Northern Pike are in about 60% of basins where Creek Chub are present. Intensive grazing is much more patchy, perhaps 5% of species range in Montana. So, overall, 50% of Creek Chub r

    ImmediacyModerate - Threat is likely to be operational within 2-5 years.

    CommentOngoing.

    Intrinsic Vulnerability

    ScoreC - Not Intrinsically Vulnerable. Species matures quickly, reproduces frequently, and/or has high fecundity such that populations recover quickly (< 5 years or 2 generations) from decreases in abundance; or species has high dispersal capability such that extirpated populations soon become reestablished through natural recolonization (unaided by humans).

    CommentLongevity of 3-4 years

    Environmental Specificity

    ScoreB - Narrow. Specialist. Specific habitat(s) or other abiotic and/or biotic factors (see above) are used or required by the Element, but these key requirements are common and within the generalized range of the species within the area of interest.

    CommentSpecies requires gravel substrates for spawning. Carnivores that eat insects and other fish.

    Raw Conservation Status Score

    Score 3.5 + 0.0 (area of occupancy) + 0.0 (environmental specificity) + 0.0 (short-term trend) + (threats) = 3.5

 
General Description
The creek chub is native to prairie streams in the extreme eastern part of Montana and is most common in the smaller Perennial Prairie Stream Ecological System. It differs from most minnows in that, similar to trout, the males dig a nest for the spawn and cover the fertilized eggs with stones to protect them. Creek chubs are also more piscivorous than most minnows, readily eating other small fish. In several areas of the U.S., creek chub are used as bait fish. They can attain a length of about 6 inches in Montana and 12 inches elsewhere.

Diagnostic Characteristics
The creek chub is silvery overall, often with purple iridescence; The back is olive and the underside white. Young have a prominent dark midside band extending from the tip of the snout to the tail fin; the band fades on older fish. The black spot at the front of the dorsal fin base is vague or absent in immature specimens. Breeding males usually have a reddish cast. A small, flap-like barbel is located in a groove of the upper lip just above each corner of the mouth, but is sometimes absent. Breeding males have a few pronounced projections on the head and smaller ones on the body and pectoral fins.

Species Range
Montana Range

Click the legend blocks above to view individual ranges.

Western Hemisphere Range

 


Range Comments
Native range includes the Missouri, Mississippi, Ohio and Tennessee River drainages, from eastern Montana, Canada and North Dakota south to Louisiana and Texas; Mississippi River from headwaters to mouth. In Montana, this species is found far east of the continental divide in streams of the Northwestern Great Plains (Yellowstone River and Little Missouri) Ecoregions. Expansions of the creek chub to the Upper Missouri basin is due to introductions.

Summary of Observations Submitted for Montana
Number of Observations: 633

(Click on the following maps and charts to see full sized version) Map Help and Descriptions
Relative Density

Recency

 

(Observations spanning multiple months or years are excluded from time charts)



Habitat
Creek chubs show a high preference for creek habitat. They are less frequent along the margins of rivers, lakes, and impoundments.

Food Habits
Creek chubs are very carnivorous. The diet includes insects, crayfish, snails, worms, and a considerable amount of fish. Also a small amount of vegetation is consumed.

Reproductive Characteristics
Creek chubs are sexually mature at the end of the 2nd or 3rd growing season. Spawning occurs from late March through June. The male builds the nest and may spawn with several females.

References
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Citation for data on this website:
Creek Chub — Semotilus atromaculatus.  Montana Field Guide.  .  Retrieved on , from