Animal experts have noted that harbor porpoises are "living in the fast lane." Being smaller than other cetaceans and living in cold northern waters means that the porpoises require a lot of energy to survive, making them prone to starvation.
Curious to learn more about porpoise's lifestyle, Wisniewska and colleagues attached miniature computers developed at the University of St. Andrews to five wild porpoises. The computers recorded the porpoises' echolocation calls and the echoes that came back as those calls bounced off of nearby prey.
By analyzing the sounds, the researchers were able to determine how often porpoises attempted to catch fish. They could also estimate the size of those fish and whether the fish managed to escape.
"This is the first time we have been able to measure simultaneously how a marine mammal hunts and how often it is successful," Wisniewska said. "The trick here was to tap into the echolocation sounds that porpoises use to sense their environment. Porpoises make hundreds of clicks a second as they approach prey, and the echoes coming back give us incredible detail about what the prey are doing."
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The data showed that the porpoises hunt around the clock. The marine mammals are also incredibly successful in landing their prey.
"We were surprised by the efficiency with which these small predators feed," Wisniewska said. "A success rate of over 90 percent, translating into as many as 3,000 fish caught per day, means that porpoises are among the most successful known hunters."
There is little room for error, though, given that a porpoise can easily go hungry if its prey, ability to hunt, or other facets of its "fast lane" life are compromised.
The researchers next plan to explore the porpoise's different foraging tactics, such as hunting in various parts of the water column. The scientists will also investigate how noise from ship traffic or other human activities could affect the harbor porpoise's ability to hunt.
SEE PHOTOS: Mammals of the Sea