Humpback whale fluke at start of dive.

Humpback whales migrate thousands of miles each year. They spend the summer fattening up on seasonally-abundant prey at high-latitude feeding grounds and spend the winter mating and calving at low-latitude breeding grounds. Scientists have been studying humpback whales in feeding and breeding areas of the North Pacific for many years–even decades in some locations–but did not have a comprehensive understanding of the links between these areas until a large, collaborative study took place in 2004–2006.