Cooperative hunting among the orcas?

From the National Post:

The orcas will wait all day for a fisher to accumulate a catch of halibut, and then deftly rob them blind. They will relentlessly stalk individual fishing boats, sometimes forcing them back into port.

Most chilling of all, this is new: After decades of relatively peaceful coexistence with cod and halibut fishers off the coast of Alaska, the region’s orcas appear to be turning on them in greater numbers.

“We’ve been chased out of the Bering Sea,” said Paul Clampitt, Washington State-based co-owner of the F/V Augustine.

Like many boats, the Augustine has tried electronic noisemakers to ward off the animals, but the orcas simply got used to them.

“It became a dinner bell,” said Clampitt.

John McHenry, owner of the F/V Seymour, described orca pods near Alaska’s Aleutian Islands as being like a “motorcycle gang.”

“You’d see two of them show up, and that’s the end of the trip. Pretty soon all 40 of them would be around you,” he said.

A report this week in the Alaska Dispatch News outlined instances of aggressive orcas harassing boats relentlessly — even refusing to leave after a desperate skipper cut the engine and drifted silently for 18 hours.

Sperm whales are getting into the act too. Here's a video of whales skimming a line:

"After a particularly heavy assault by sperm whales, fishers are known to pull up lines in which up to 90 per cent of the catch has disappeared or been mangled."

H/t Tyler Cowen.