Tracking individual mormyrid electric fish in the field using electric organ discharge waveforms

Electric organ discharges (EODs) from African mormyrid weakly electric fish can be species-, sex- and individual-specific. In this study, small EOD differences were used to track the day-to-day movements of individuals from two species of Brienomyrus in their natural stream habitat in West Africa. Waveforms were digitized and 15 measurements were taken of amplitude, time and spectral characteristics. For quantitative comparisons, the measurements were transformed by principal components analysis. By matching similar EODs from one day to the next, best guesses were made as to the daily movement patterns of individuals. Sexually mature males, females and juveniles all tended to return to the same daytime hiding place on successive days (median movement of 1 m).