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Tracking sperm whales and jumbo squid
 The sperm whale and its large prey, the jumbo squid, are among the deepest divers in the ocean, routinely reaching depths of 3,000 feet or more. Now, in a new study, a team of marine scientists reports the successful tagging of sperm whales and jumbo squid swimming together off Mexico's Pacific coast - the first time that electronic tracking devices have been applied simultaneously to deep-diving predators and prey in the same waters.
Sperm whales and jumbo squid are both major predators that spend much of their lives in very deep waters, however how sperm whales search for, detect and capture their prey remains uncertain. To find out, researchers travelled to the Gulf of California, also called the Sea of Cortez - a narrow stretch of ocean that separates the Mexican mainland from the Baja Peninsula. It is very rare to find an area where sperm whales are seen together with their prey and as these whales specifically obtain their food in unknown zones below the surface, it has always been challenging research for scientists. Adult sperm whales can stay underwater for more than an hour and nobody knows exactly what they're doing down there.
During six days at sea, the research team identified 74 individual sperm whales in a 27-square-mile area. To locate the whales, researchers towed an array of hydrophones from the back of a boat and listened for the animals' distinct clicking vocalisations. When they finally encountered a whale, the scientists carefully approached the animal and attached an electronic depth recorder to its back. Later, whenever the tagged whale surfaced for a breath of air, the device would transmit recorded data about the animal's movements to an orbiting satellite.
 During the study, electronic tags were placed on five whales and also three jumbo squid swimming nearby. Analysis of the tagging data showed that the whales were travelling up to 60 miles a day within a relatively small area, suggesting that they had found an abundant supply of food. During the day, the whales and squid spent about 75 percent of their time at depths ranging from 600 to 1,300 feet. At night, however, the tagged squid spent at least half of their time in shallower waters above 600 feet and the remainder at 600 to 1,300 feet. Unlike the squid, the whales did not alter their diving pattern at night and instead, continued to spend about three-fourths of their time at depths of 600 to 1,300 feet, whether squid were there or not.
As no one has ever seen a sperm whale feeding in the wild, nobody really knows how they capture their food. This new research will now provide further opportunities to learn more about two species that are very difficult to study in their natural habitat. Jumbo squid can weigh more than 100 pounds and grow more than 6 feet long. Sperm whales are the biggest of all the toothed whales and inhabit every ocean. The adult males can reach 60 feet in length and 57 tons.
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