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Montana Animal Field Guide

Montana Field Guides

Plains Minnow - Hybognathus placitus

Potential Species of Concern

Global Rank: G4
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 plains minnow 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
    Plains Minnow (Hybognathus placitus) 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)

    Comment187,315 square kilometers based on Natural Heritage Program range maps

    Area of Occupancy

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

    Comment412 square kilometers based on Heritage Range Maps and occupancy of 1% of landscape by streams and occupancy of 22% 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. Recent prairie fish surveys did not detect them in the Marias River basin or the Milk River basin upstream of Frenchman Creek, but it is uncertain whether this means decline or previous issues with identification.

    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.

    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. Perhaps the majority of prairie streams affected by intensive agriculture are capable of recovering to the point of supporting populations within 50 years. They do not currently

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

    Comment75% of Plains Minnow range overlaps with the range of Northern Pike. Right now there is very little overlap in streams where Plains Minnow and Northern Pike are both detected (only 21% or 6 of 28 streams). It is difficult to ascertain whether Plains Min

    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

    ScoreC - Moderate. Generalist. Broad-scale or diverse (general) habitat(s) or other abiotic and/or biotic factors are used or required by the species but some key requirements are scarce in the generalized range of the species within the area of interest.

    CommentPresent in a variety of prairie stream sizes and substrates. Seem to handle a variety of turbidities, plant densities, and water temperatures as well.

    Raw Conservation Status Score

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

 
General Description
The plains minnow is similar to the western silvery minnow in many features. It is native, silvery in color, found in the same major drainages and even at the same sites as the western silvery minnow, eats similar foods and attains about the same size. The plains minnow is so similar to the western silvery minnow that the two can only be told apart after making a dissection and examining a certain bone in the head.

Diagnostic Characteristics
Overall, the plains minnow is very silvery; the back is dusky or yellowish-olive, and the underside is white. The plains minnow has 15 to 22 scales across the belly from lateral line to lateral line.

Species Range
Montana Range

Click the legend blocks above to view individual ranges.

Western Hemisphere Range

 


Range Comments
Native range includes the Missouri, Arkansas, Red, Brazos, and Colorado River drainages, from Montana and North Dakota south to New Mexico and Texas; Mississippi River from mouth of Missouri River to mouth of Ohio River. In Montana, this species is found east of the continental divide in streams of the Northern Prairies and Northwestern Great Plains Ecoregions.

Summary of Observations Submitted for Montana
Number of Observations: 539

(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
Habitat for the plains minnow is probably similar to that for the western silvery minnow. Seventy percent of specimens in a southeast Montana study were taken in the mouths of streams, showing their preference for larger streams.

Food Habits
Food habits are probably very similar to the western silvery minnow.

Ecology
The ecology of the plains minnow is very similar to H. argyritis. They are distinguishable by the pharyngeal process of the basioccipital.

Reproductive Characteristics
Reproductive biology is probably very similar to the western silvery minnow.

Threats or Limiting Factors
Threats to this minnow species is largely from introduced predatory fishes, such as northern pike and walleye.

References
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Citation for data on this website:
Plains Minnow — Hybognathus placitus.  Montana Field Guide.  .  Retrieved on , from