Otolith Increments and Elements: Assessing a Recently Discovered Population of Weather Loach

Abstract

The introduction of aquatic non-native species into novel systems may have negative impacts on native biodiversity. Introduced species can predate native species, compete for resources, transmit diseases, hybridise and degrade habitat. To minimise impacts on aquatic biota, management efforts are needed to reduce invasive species abundance. However, eradication or reduction efforts require information about the source of introductions and the biology and ecology of the organism. Therefore, the objective of this study was to quantify population dynamics, natal origins and dispersal characteristics of the introduced Weather Loach Misgurnus anguillicaudatus, which was recently discovered in Georgia, USA waters. Sagittal otoliths were extracted and aged to determine dynamic rate functions, and we performed microchemical analysis on a subset of otoliths to quantify dispersal and introduction events. Sampled Weather Loach consisted of a wide range of ages and lengths, indicating that natural reproduction and recruitment have been occurring for multiple years. The change in otolith microchemistry seen in some fish reveals that they have dispersed from their introduction or reproduction sites into different areas, while others have likely remained in the same system since hatching. Overall, our findings indicate that the Weather Loach populations in Georgia are disjunct, likely stemming from multiple introductions. These results will be used to develop management strategies as well as aid in the effort to continue and enhance outreach regarding the release of unwanted aquarium fish.