Pinnipeds including seals and seal lions normally experience a successful birth rate of 80 percent, but in El Nino years, that drops to 20 percent. "Most of the offspring die," Mate said, "because the mothers cannot produce enough milk."
The TOPP study was the first ocean basin-scale study of marine predator distribution and movement ever conducted, and the massive amount of data collected will help resource managers develop effective ocean protection strategies, the researchers say.
The study underscores the importance of apex predators in different ecosystems, noting how the loss of bluefin tuna and porbeagle sharks in the Atlantic Ocean contributed to the near-extinction of cod and similar species.
Mate, a pioneer in the use of satellites to track endangered whales and other species, has been studying blue whales for decades and has been featured in the National Geographic Magazine and the National Geographic Channel film, "Kingdom of the Blue Whale." Most of that documentary was shot aboard OSU's research vessel Pacific Storm, which tracked blue whales tagged off California in the fall to their first-ever discovered winter breeding and calving area 500 miles off Costa Rica in an upwelling area.
Blue whales may be unique among large whales in using areas for reproduction where they can continue to feed. Interestingly, the whales do not have just one route for this migration but instead use a variety of offshore routes and variable timing.
Adult blue whales can grow to the length of a basketball court and weigh as much as 25 large elephants combined. A blue whale's mouth could hold 100 people, Mate said, though its diet is primarily one-and-a half-inch long krill. The he
|Contact: Bruce Mate|
Oregon State University