RARE AND DECLINING FISHES OF SOUTH DAKOTA: A RIVER DRAINAGE SCALE PERSPECTIVE

Abstract

We summarized the status of fishes that have declined from one or more of the 14 major river drainages in South Dakota and of fishes that are restricted to only one river drainage in the state, even if they have not declined. These species are of conservation concern because declines indicate sensitivity to environmental change and restricted distributions indicate relatively high extinction risk. We documented 35 species that had declined from one or more river drainages and six species that have not declined, but are restricted to only one river drainage. The species were not necessarily of equal conservation concern because some had declined more than others, and some maintained greater present-day (post-1990) distributions than others. Thus, we determined relative conservation concern by combining the numeric rank of each species by the number of drainages from which it was missing with the number of drainages presently occupied. We also used a literature review to summarize impacts that affect each species elsewhere. This review suggested that impacts of erosion (siltation, pollution) and channel modification (channelization, riparian degradation, etc.) are the most substantial, but barriers to dispersal, water withdrawals, and wetland drainage are also important. This analysis is limited because it only considers declines at the riverdrainage scale, but it nonetheless provides the first comprehensive summary of the status of South Dakota fishes.