The USGS, Cooperative Research Units in Reston, VA, supporting the Ecosystems Mission Area requests the purchase of one stereomicroscope imaging system. The primary use is to support the fisheries and aquatic sciences research program of the South Dakota Cooperative Fish and Wildlife Research Unit (SD CFWRU) for conducting laboratory analyses associated with fisheries management, aquatic ecology, resource conservation, and graduate student research. The stereomicroscope imaging system will be used for otolith preparation and interpretation, microchemical evaluations, age and growth analyses, fish diet analysis, macroinvertebrate identification, larval fish identification, tissue examination, morphometric measurements, and high-resolution imaging of biological specimens for scientific publication and reporting. The stereomicroscope imaging system must provide high-resolution optical performance capable of producing clear, repeatable observations and digital images across a wide range of biological specimens. The system must support ongoing collaborative research projects involving invasive carp, paddlefish, sportfish management, aquatic habitat assessments, fish population dynamics, and other fisheries and aquatic ecology investigations conducted by the SD CFWRU and its cooperators.