"We also know relatively little about the behavior of jumbo squid in the wild," Gilly added. "For example, it was only a couple of years ago that we discovered an area in the central Gulf of California where spawning and mating of these animals probably take place."

Electronic tags

The MEPS study was conducted in fall 2004 near Santa Rosalia, a coastal Baja California town that is the center of Mexicos jumbo squid fishery.

During six days at sea, the research team identified 74 individual sperm whales in a 27-square-mile area. To locate whales, researchers towed an array of hydrophones from the back of a boat and listened for the animals distinct clicking vocalizations. 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 animals movements to an orbiting satellite.

Jumbo squid also were abundant, with numerous small fishing boats hauling in a total catch of about 10,000 squid per night throughout the six-day study. Captured squid were outfitted with a pop-up archival transmitting tag, which periodically sampled the animals depth. Unlike the instruments used on whales, the squid tags were designed to detach at a predetermined time, then float to the surface and transmit stored data to the satellite.

Results

During the study, electronic tags were placed on five whales and three jumbo squid swimming nearby. Analysis of the tagging data showed that the whales were traveling up to 60 miles a day within a relatively small area, suggesting that they had found an abundant supply of food.

The tagged predators and prey must have crossed paths at some time during the experiment, Gilly noted. "Based on the locations of where the squid tags first a
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Contact: Mark Shwartz
mshwartz@stanford.edu
650-723-9296
Stanford University
8-Mar-2007