Mating calls of three prochilodontid fish species from Brazil

Passive acoustic monitoring (PAM) of fish sounds has been used as a means of detecting the presence and abundance of fishes. Prior to PAM, bioacoustical analyses of sounds are needed to characterize species-specific characteristics of calls. With hydrophones placed in outdoor ponds, we recorded the mating calls of three species of prochilodontid fishes (Prochilodus argenteus, P. costatus, P. lineatus). Fish were induced to spawn and call by injection of carp (Cyprinus carpio) pituitary gland extract. We recorded a total of 394 pulse train calls and additional single pulse calls that were not associated with trains. The trains of all three species were similar in nature - series of low frequency pulses that lasted from 1 to 11 s, often with an initial rapid rise followed by a slow tapering of pulse amplitude. Dominant frequency of single pulses and trains was greatest in P. lineatus, with P. costatus and P. argenteus exhibiting lower single pulse dominant frequencies, and P. costatus having lower train dominant frequency. With data from the three species combined, the dominant frequency of pulses significantly increased with fish standard length. There was also a significant linear relationship between the dominant frequency of pulses and trains. Discriminant function analysis showed that differences in train dominant frequency, pulse duration, and pulse period between the three species were significant enough to discriminate between them. This study was the first to fully characterize the sounds of these three Prochilodus species, and should assist fisheries biologists monitoring spawning behavior in these species.