John Driscoll - The Times-Standard

In nearly a quarter century studying humpback whales, researcher Fred Sharpe has witnessed a remarkable recovery.

The intelligent and social animals have rebounded from centuries of whaling, and are filling in their historic range. Sharpe, a founder of the Alaska Whale Foundation, said the whales have even made a comeback along the California and Oregon coasts, where as recently as the early 1960s some 2,000 humpbacks were killed.

Whaling was largely outlawed in the 1960s, though illegal Russian whaling persisted into the 1970s.

Sharpe attributes the increasing numbers to the humpbacks' flexibility in what they eat -- everything from squid and salmon to small crustaceans -- and their complex social systems.

”They consistently seem to blow the doors off bounded rationality,” Sharpe said.

They appear to be able to react to changing ocean conditions, and adapt to a variety of man-made hazards like sonar, engine noise from boats, ship strikes and getting tangled in fishing gear, Sharpe said.

Humpbacks can be seen off the Northern California coast in substantial numbers in May. Unlike gray whales that typically are only seen by their spout, humpbacks lunge to the surface to feed, exposing their heads, and show their tails when they dive. Adult whales can be 50 feet long and weigh up to 40 tons.

The humpbacks seen in this region are part of a group that that breeds off Central and South America and migrates north to feed in Northern California and Washington waters.

Another group winters off Hawaii and migrates to feeding grounds in Alaska. In the fjords off Alaska, the whales display their impressive collective hunting technique of trapping fish in a curtain of air bubbles, then rushing into the school with open mouths.

A major international study called SPLASH -- Structure of Populations, Levels of Abundance and Status of Humpbacks project -- has given biologists a picture of humpbacks throughout the North Pacific. Believed to have been driven down to a mere 1,400 individuals at the end of whaling in 1966, a 2008 report now estimates that 18,302 humpbacks live in the North Pacific. That's almost double the estimate made in 1991 to 1993.

The estimate “represents a dramatic increase in abundance from other post-whaling estimates for the overall North Pacific,” the SPLASH report reads, “yet is consistent with a moderate rate of recovery for a depleted population.”

Worldwide, their numbers are estimated at 30,000 to 40,000, according to the American Cetacean Society, about 30 percent of the pre-whaling population.

The rebound is impressive for an animal that can produce only one calf per year, and averages a calf every two to three years, Sharpe said. But the humpback is highly mobile and an efficient traveler. They form large teams, Sharp said, and designate individuals to lead tasks, and they have a complex system of communication that people still do not fully understand.

Sharpe said that the recovery of the humpbacks shows their amazing adaptability, but also that the oceans still hold an abundance of food.

”Our earth has got some health still,” Sharpe said, “it's got some vitality.”