Giving a hoot about cardinalfishes

The cardinalfish family Apogonidae contains about 380 species distributed in tropical regions of the Atlantic, Indian, and Pacific Oceans. Relatively little is known about the details of their social behavior, such as if they produce sounds for specific purposes. Chang et al. found cardinalfishes produce sounds when reproducing or fighting, which may help scientists monitor species distribution, movement, and reproductive conditions.

Nine cardinalfish species at Dongsha Atoll in the South China Sea were studied. The team found they produced sounds like tonal grunts and knocks. However, only one of the nine – the Fowleria variegata – produced harmonic hoot calls. The hoot calls could be even further differentiated, producing short calls during agonistic (or combative) situations, and long calls to signal its presence for reproductive reasons. These hoot calls were often heard by divers and in sea grass meadows.

“Hoot calls were the common sound type heard by divers near coral patches, especially the branched coral, Acropora, and also in seagrass meadows at Dongsha Atoll in the South China Sea,” Hin-Kiu Mok said, adding that the team captured field audio recordings at different locations to search for fish sounds. “After the hoot calls were located at the branched coral patches, fishes within the coral patch were captured, and species were kept in separate aquarium tanks, which allowed us to identify the calling species.”

Mok said the team has several follow-ups in mind for the study, including taking closer audio and image recordings to understand the fishes’ complete courtship behaviors and why hoot calls were only found in one species.

Source: “Vocal repertoire and sound characteristics in the variegated cardinalfish, variegata (Pisces: Apogonidae),” by Hai-Jing Chang, Hin-Kiu Mok, Michael L. Fine, Keryea Soong, Yu-Yun Chen, and Te-Yu Chen, The Journal of the Acoustical sSociety of America (2022). The article can be accessed at https://doi.org/10.1121/10.0016441 .