November 6, 2018, Acoustical Society of
America
A piranha's bite is definitely
worse than its bark, but the bark has uses too. A new study of the sounds made
by piranhas in the Amazon finds that their underwater "barks" are an
effective tool for identifying different species in murky waters.
Scientists have previously documented
several noises that piranhas make by contracting muscles near their gas
bladders, but these studies primarily occurred in a laboratory.
Next month, Rodney Rountree,
"The Fish Listener," will talk about his work with Francis Juanes of
the University of Victoria, to document calls made by fish in the
Pacaya-Samiria National Reserve in Peru in a presentation at the Acoustical
Society of America's 176th Meeting, held in conjunction with the Canadian
Acoustical Association's 2018 Acoustics Week in Canada, Nov. 5-9 in Victoria,
British Columbia. These calls may be useful for tracking piranha populations
through passive acoustic monitoring.
"In the Amazon, most of the
habitats are very turbid so you usually can't put cameras down and watch the
behavior. The only way to survey fish is to catch them," Rountree said.
"Passive acoustics lets you potentially locate fish just by their
sounds."
During routine surveys at the reserve
in 2012, Rountree "auditioned" captured fish by holding them gently
underwater next to a hydrophone to record any noises. In total, he auditioned
more than 550 individuals from at least 70 fish species,
including four types of piranhas. Using statistical analysis, Rountree could
differentiate between piranha species, even closely related ones, based on the
pattern of their barks.
Rountree also recorded underwater
soundscapes at 22 sites in the reserve. He heard similar piranha barks at
locations where piranhas were known to be feeding, as well as startled calls
from catfish and other prey. "When piranha are present and feeding, they're
nipping and biting, so the other fish are making lots of sounds," he said.
Posts
