New peril for gray whale survival? Predatory orcas spotted in Baja calving lagoon
Baja California , June 29, 2010
In addition to the great white sharks and orcas seen near the cetacean’s nesting ground along the Pacific Coast in Baja California, there had been reports earlier this summer of large, dangerous killer whales attacking whales in the Mexican Pacific.
Although most of the recent reports were anecdotal, a new analysis using satellite tracking data suggests that the large predators may be beginning to track whales and even attack them on an extremely regular basis.
The new data shows that the killer whales have been traveling from the southern Pacific to the Baja California coast, and that their movements have been relatively predictable.
The researchers found that the whales appear headed in the direction of the California Current, one of the fastest currents in the world. The whales pass from the southern to the northern part of the Pacific and travel along it by roughly 30 to 40 miles per day.
“They’re always moving; they don’t stay for very long…They never stop,” said Robert Ballard, director of the Woods Hole Oceanographic Institution and a co-author of the new study. He was also a co-author of the 2009 study that found more orcas and great whites near the Pacific, and a co-author of a 2012 study that suggests more orcas are seen near the Hawaiian Islands. “They’re always going east — they almost always head north.”
The researchers analyzed information from more than 400 satellite transmissions from the U.S. Navy’s Deep Submergence Rescue Vehicle (DRSV) and the Japanese Remote Sensing Systems (J-RSS). In addition to the J-RSS data, the DRSV also transmitted data to the Center for Polar and Oceanic Research at the University of Central Florida (USF), which analyzed the data to track the whales.
Using analysis of the data, the researchers were able to determine the whales’ specific locations.
The analysis showed that the whales had moved from their normal ocean residence to the Baja coastline, and that most travels were between mid-May and mid-June. They reached depths of more than 600 meters
