Fish Stick Together Through Communication To Stay Safe

Researchers found that fish communicate to protect themselves against predators in a similar way like elephants and chimpanzees, according to a study at the University of Auckland. This latest study is one of the first to provide direct evidence that shows that fish communicate to maintain group cohesion. Scientists are aware that fishes send messages to each other for protection or for mating purposes. However, in this study, the researchers proved that fish can also use contact call to keep members of their shoal together.

The researchers carried out their study by using wild Bigeyes (Pempheris adspersa), a common fish species, which is found along the coast of New Zealand. Bigeyes are mostly nocturnal, where they spend most of the day in caves and they search for food at nights in loosely-knit shoals.

Studies have shown that Bigeyes have a unique "pop" call with an estimated maximum range of 31.6m. Their vocal behavior is connected to sensitive hearing organs, which led the researchers to believe that Bigeyes communicate in groups. However, until now that has been ineffective.  

The researchers used underwater hydrophones, a GoPro camera and an MP3 player along with 100 fish, which were placed in saltwater tanks at the Leigh Marine Laboratory. The experiment was carried out for a period of five months. Two types of sounds were played to the fishes, one was of the regular reef environment in which the fish first lived in and the other was a recording of Bigeye vocalizations.

The researchers noted that when the sound recordings were played, the Bigeyes's calling rates increased five times so that they can contact over and above the background noise. The Bigeyes also swam closer to each other when the recordings were played. The fishes swam apart when there was no sound.

"This study means that fish are now the oldest vertebrate group in which this behavior has been observed and that has interesting implications for our understanding of evolutionary behavior among vertebrates,"  Lucy van Oosterom, lead author of the study, said in a news release.

The findings of this study were published in Scientific Reports.

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