Individual and sex specificity in the electric organ discharges of breeding mormyrid fish (Pollimyrus isidori).

I monitored the electric organ discharges (EODs) of 14 Pollimyrus isidori, (Cuvier and Valenciennes) during an artificially induced breeding season, to examine sex and individual differences in reproductive fish. EODs were repeatedly recorded over an 11-day period to ascertain the stability of each individual's EOD and to make a quantitative assessment of sex differences. Within days, I found the individual's EOD to be constant from one EOD to the next. Over the 11-day sampling period, individuals were also quite stable and exhibited only slight changes in EOD duration and relative amplitude of the phases of the waveform. I found that the differences between individuals of the same sex were highly significant in measures of EOD duration and in measures of the relative amplitude of the phases. Differences between the sexes were also highly significant in relative amplitude but were not significant in duration. In a multivariate discriminant function analysis, I have found that individual fish can be correctly classified on the basis of temporal, relative amplitude and spectral cues in the EOD, despite slight changes in these parameters with time. The EOD exhibits characteristics of a good signature in the context of an information system.