Habitat associations and demographics of a newly recorded population of taillight shiner in Illinois

The taillight shiner, Notropis maculatus (Hay in Proc United States Natl Museum 3:488-515, 1881), primarily occurs in the southeastern United States, with rare occurrences in Illinois, where it is state listed as endangered. The first observation in Illinois was in 1987 and the species was last seen in the state in 1988. However, the taillight shiner was recently rediscovered in Buttonland Swamp within the Cache River watershed in September 2020 during fish community surveys. A total of 311 taillight shiners were captured from September 2020 to October 2022 within Buttonland Swamp using electrofishing, mini fyke nets, and light traps from the fish community surveys. Habitat associations were assessed using repeated measures mixed models and a conditional inference tree was developed to assess the probability of taillight shiner occurrence in electrofishing samples based on habitat variables and dissolved oxygen. We also assessed differences in taillight shiner length among years and seasons. Emergent vegetation was particularly important in predicting the occurrence of taillight shiners in samples, with dissolved oxygen and silt/clay also being important. Taillight shiner length distributions were similar among years and significantly different among seasons. Spawning occurred in spring, while post-spawn mortality occurred between June and August. This study provides important information regarding habitat associations, probability of occurrence in samples, recruitment, and timing of post-spawn mortality of taillight shiners in Illinois, which could inform future sampling efforts in Illinois and adjacent states. This rediscovery indicates that the taillight shiner is still present in Illinois and further search efforts to assess the species’ status in Illinois are needed.