Cooperative Fish and Wildlife Research Units Program: Montana Fishery
Education, Research and Technical Assistance for Managing Our Natural Resources

Montana Fishery Project

Habitats and Movements of Spiny Softshells in the Missouri River in Montana

May 2009 - December 2013


Participating Agencies

  • US Bureau of Reclamation through CESU agreement
  • Montana Fish Wildlife and Parks
  • Bureau of Land Management through RWO
Apalone spinifera, Missouri River, Montana

Little is known about the populations of spiny softshells Apalone spinifera hartwegi, in Montana, where they are a state Species of Concern, a Tier 1 Species with greatest conservation need, and a Bureau of Land Management Sensitive Species. The spiny softshell populations upstream of Ft. Peck Dam are isolated from other Montana populations, and are therefore at risk of extirpation. Although dam operations affect riverine and riparian habitats, the relationships between hydrograph and use of habitats for nesting, feeding, basking, and overwintering by spiny softshell are not known. Recreation and cattle grazing are prevalent land uses in the Missouri Breaks National Monument and the Charles M. Russell National Wildlife Refuge. Spiny softshells may be particularly vulnerable to human disturbance and have been observed to abandon nesting when a boat or human came within visual range. Our overall goal is to document how human activities, i.e., dam operations and hydrograph, recreation, and cattle grazing affect spiny softshell habitat use, movements, nesting behavior and site selection, and overwintering locations in a ~ 50 mile reach of the Missouri River from Judith Landing on the Upper Missouri Breaks National Monument downstream to the Fred Robinson Bridge on the Charles M. Russell National Wildlife Refuge. This reach spans a gradient of spiny softshell catch per unit effort ranging from 16.7 turtles per trap night in the upstream part of the reach to 0.3 turtles per trap night near the downstream end.