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As the result of anthropogenic disturbance, freshwater ecosystems are rapidly being destroyed worldwide. Accordingly, such impacts are also resulting in the loss of aquatic biodiversity. Specifically, the introduction of non-native aquatic species is becoming an increasing concern. Historically, many non-native freshwater fish introductions have been the result of commercial baitfish aquaculture and private aquarium release. Cyprinella lutrensis (the red shiner) is endemic to much of the central U.S., and its natural range does not extent east of the Mississippi River. Since the 1950’s, red shiner have been cultivated and transported across the globe as both bait and aquarium fish. During the early 1990’s, invasive red shiner populations were first observed in the Coosa River Basin, located in northwest Georgia, USA. Originating from bait bucket releases, invasive red shiner have quickly established in this area, and readily compete and hybridize with at least one native species of Cyprinella (Cyprinella venusta), the blacktail shiner. Over the past thirty years, red x blacktail shiner hybrids are becoming more abundant and demonstrate an uncertain level of viability. To date, little is known about the relative fitness of red x blacktail shiner hybrids compared to parental species. If hybrids exhibit a higher level of fitness compared to parental species, then this could result in regional extinctions of native stream fishes. To better understand the relative fitness of native blacktail shiner vs. hybrid shiner, we examined swimming performance as a widely accepted proxy. Blacktail, red, and hybrid shiner were collected in Northwest Georgia during the time frame of August 2020- March 2021. Individual swimming performance trials were then conducted in a recirculating flow chamber. During these trials, a suite of physiological and morphometric measurements were recorded. Here, we present an analysis of our preliminary data, investigating differences in fitness among native and hybrid shiner.



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