Invasive Asian carp have posed persistent ecological and management challenges in U.S. waterways since their introduction in the 1970s. Species such as grass and silver carp alter aquatic ecosystems by disrupting food webs through sediment resuspension and competition with native organisms. Effective management would benefit from improved tools for detecting carp presence and reproductive activity in near real time. Fluorescent spectrophotometry, widely used to characterize dissolved organic matter and contaminants in aquatic systems, may provide a novel approach for detecting carp milt as an indicator of spawning activity. However, the fluorescent properties of fish milt and its detectability relative to background water remain largely unexplored.
This study evaluated whether invasive carp milt exhibits distinct fluorescence signatures that can be differentiated from well water. Grass and silver carp milt samples were provided by the U.S. Geological Survey Central Midwest Water Science Center and analyzed at multiple dilutions using a Cary Eclipse fluorescence spectrometer. Synchronous excitation–emission scans were collected and processed in RStudio to generate three-dimensional excitation–emission contour plots. Samples were reanalyzed after 24 hours to evaluate changes in fluorescence intensity over time.
Results indicate that carp milt fluorescence is distinguishable from well water and that grass and silver carp display different relative fluorescence patterns. Fluorescence intensity decreased after samples were left overnight, suggesting temporal degradation of detectable signals. While these findings are preliminary, they demonstrate the potential for fluorescence-based detection of carp biological material. If reproducible, this approach could support the development of in-situ sensors to improve monitoring and management of invasive carp populations.