Blue Sucker Summer Utilization Distributions and Inter-annual Fidelity to Summering Habitats

Blue Sucker Cycleptus elongatus populations in the Missouri River are believed to be declining. The decline is most likely attributable to anthropogenic modifications including channelization and dam construction. We compared 2008 and 2009 summer use distribution (UD) for 21 blue suckers implanted with acoustic tags to better understand how blue suckers use the Missouri River. UDs are used to analyze space-use requirements based on the home range concept. The geometric mean 95% UD range was 1.9 river kilometers (RKM) in 2008 and 0.3 RKM in 2009, and differed statistically by year. The upper bound of the 2008 95% UD accounted for 96% of the variation in the upper bound of the 2009 95% UD when regressed against each other, and the slope did not differ from one, which indicates that UD boundary locations were similar between years. Results were similar for the lower bound. Blue suckers appear to have a high degree of fidelity to sites occupied during the summer even though they undertake substantial (>20 RKM) seasonal migrations. This fidelity could increase the species’ vulnerability to natural and anthropogenic disturbances, however, knowledge of this behavior should also serve as a guide for conservation efforts.