How many squids does a short-finned pilot whale need to survive? An international team of biologists in the waters around Hawaii fitted eight of these tropical water-dwelling dolphins with a state-of-the-art transmitter, including a built-in camera, GPS and a hydrophone to record echolocation. In this way, the scientists wanted to shed light on a larger question: are there even enough squid in that part of the Pacific Ocean to sustain the pilot whale population there?
Short-finned pilot whales can dive up to 1,700 meters deep to search for food and are therefore difficult to study. Thanks to the transmitters (attached via a suction cup), the biologists could now watch during such a dive. The results they describe in it Journal of Experimental Biology. They discovered that dolphins dive about 39 times a day and consume about 73.8 kilojoules per minute. Based on the echolocation clicks, the researchers suspect that one pilot whale consumes four squid per dive and that each squid produces approximately 560 kilojoules of energy.
To survive, a pilot whale would need between 82 and 202 squids per day, they calculate: up to 73,730 per year. Together, the roughly 8,000 pilot whales would eat almost 600 million squid annually. That sounds like a huge amount, but the biologists are not worried – there is more than enough food for the pilot whales around Hawaii, they conclude.
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