An Aquatic Gap Analysis of Riverine Ecosystems throughout the Missouri River Basin

The Missouri River Basin encompasses portions of ten states and two Canadian provinces.  It is the second largest river basin in the United States, is ecologically diverse, and drains approximately 17% of the country.  The Gap Analysis Program’s goal is to keep common species common by assessing representation within the existing matrix of conservation lands.  To help achieve this goal within the Missouri River Basin the Missouri Resource Assessment Partnership (MoRAP) recently completed an aquatic gap analysis of the entire basin.  This effort brought together Gap Analysis Program data developed by several organizations covering varying portions of the basin.  These data consisted of a hierarchical classification of riverine ecosystems, predicted fish distribution models, riverine stewardship characterizations, and indices of human threats that were ultimately used to assess habitats and species not adequately represented within existing conservation lands (gap analysis).  Approximately 14.5% (146,224 km) of the total stream kilometers in the Missouri River basin are contained within the existing matrix of public lands.  However, only 2.2% of the basin stream kilometers flow through lands that are managed for the long-term maintenance of biodiversity (status 1 or 2 lands) and most of these (42%) are in the Yellowstone Mountains and Plains Aquatic Subregion.  Biological diversity generally increases moving toward the lower basin while at the same time the amount of land managed for biodiversity conservation generally decreases.  As such, it becomes evident that the ecological and biological diversity of this large river basin is not consistently represented.  The results of the aquatic gap analysis help to highlight areas where additional conservation measures may be needed to ensure adequate protection of the diversity of riverine habitats and species in the basin.