Shortnose Gar (Lepisosteus platostomus) Conservation Status Review
Review Date = 07/16/2017
ScoreU - Unknown
CommentUnreliable estimates can be derived from sparse sample data and could be a significant underestimate, since this species is rarely targeted in routine fishery surveys. Data deficient!
Area of Occupancy
CommentLinear Range was calculated to be a liberal 456 km (286 river miles) of predicted occupied river extent based on MFISH river miles calculations associated with surveys, while conservative estimates of actual suitable river habitat is likely half this (143 river miles). Scores either way within the LD range.
Length of Occupancy
ScoreLD - 200-1,000 km (about 125-620 miles)
ScoreE - Relatively Stable (±25% change)
CommentEven though they have been impacted by Fort Peck dam. Due to their habitat requirements, they have probably been pretty stable in terms of available habitat since the arrival of Europeans- within +/-25%.
ScoreE - Stable. Population, range, area occupied, and/or number or condition of occurrences unchanged or remaining within ±10% fluctuation
CommentWe decided upon a stable trend, because, although we acknowledge loses of occupied river miles due to dams and diversions, this is encompassed within the 10% variability allowed. We encourage more monitoring of sites, especially in suitable habitat areas between the Yellowstone confluence and Fort Peck Dam. Monitoring and distribution in the Yellowstone River is increased at a number of sites.
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.
CommentDiversion dams, dams, pollution, oil spills and introduced species (predation by Smallmouth Bass and Northern Pike on juvenile gar 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.
ScopeModerate - 20-60% of total population or area affected
CommentShortnose Gar range overlaps with dams and diversions. Introduction of Northern Pike may have had an effect on some suitable habitats areas.
ImmediacyHigh - Threat is operational (happening now) or imminent (within a year).
CommentRank factor not assessed, although we would lean towards “Not Intrinsically Vulnerable”.
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.
CommentWe decided that the Shortnose Gar is a broad-scale or diverse habitat generalist or other abiotic and/or biotic factors are used or required by the species, but some key requirements (slow, stagnant areas) are scarce in the generalized range of the species within the area of interest. They seem to handle a variety of turbidities, substrates, and water temperature fluctuations as long as slow, stagnant areas can be found.
Raw Conservation Status Score
3.5 + (-0.25) (area occupancy+ pop) + 0.0 (environmental specificity) + 0.0 (short-term trend) + 0.0 (threats) = 3.25