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Friday, June 23, 2017

The Globe's Foremost Apex Marine Predator

"We've been chased out of the Bering Sea. [Electronic noisemakers to frighten them off?] It became a dinner bell."
"It's possible at some point they [Orcas] might start hitting the pot [conversion to giant fishing traps called pots]."
"When I started fishing in the early '80s, when we saw a whale it was an event. Now, they circle the boat."
Paul Clampitt, co-owner F/V Augustine, Washington State

"[Orca pods close to the Aleutian Islands are like a] motorcycle gang."
"You'd see two of them show up, and that's the end of the [fishing] trip. Pretty soon all forty of them would be around you."
"[Pulling up lines to see some fish merely gnawed] That was them teaching the little ones. It's unfortunate the orcas are putting us out of business, because they're really a phenomenal mammal."
John McHenry, owner, F/V Seymour, Alaska, Aleutian Islands

The animals have learned to target individual boats, and are leading fishers on high-speed chases to get away : AP Photo/Elaine Thompson)

Are animals intelligent? Can they assess situations and react to them to further their own interests? Ask the fishermen who have been experiencing some unusual episodes of new behaviour expressed by aggressive orcas, forming pods skilled in harassing boats and harvesting their fish. "Since 1997, reports of depredation have increased dramatically", a report by the Southeast Alaska Sperm Whale Avoidance Project has noted.

It has by now been well enough witnessed and documents that orcas can patiently wait for fishermen to acquire a halibut cache, even if it takes all day, to then move in to strip the fishing lines. Cod and halibut fishers off the coast of Alaska have traditionally experienced peaceful coexistence with the orcas in the region. That was then; now the orcas have turned on the fishers to strip them of their catches.

Sperm whales, large and square-headed, have been pillaging fishing lines as well. A video taken in 2006 by the Avoidance Project succeeded in filming one of the 50,000-kg whales as it delicately shook loose fish from a fishing line. "I've had the same sperm whale follow me 70 miles", complained Michael Offerman of the F/V Kristiana.

The Bering Strait separating western Alaska from Russia appears to be the locus where the worst incidents of whale hijacking of fishers has been taking place, though fishing boats across Alaska have been reporting orca harassment. The cost of fish loss from orcas appropriating the fish from lines was estimated at $500 daily, according to a 2014 study.

While a 2015 study of fishing boats in Uruguay where similar fishing techniques are used discovered "the presence of killer whales in the fishing ground seems not to affect the catch per unit effort."  A rebound of North Pacific whale populations resulting from the 1980s moratorium on commercial whaling appears to be linked to the increasing predation of whales on fishing boat catches.

Up to the rebound, cod and halibut fishers' experience had been that of moving among populations of whales surviving the hunt by whaling fleets, where survivors had learned that the approach of a boat engine spelled danger to them. Earlier, in the 1990s, researchers had discovered that a sudden collapse in Pacific sea otter populations was caused by orca predation.

The orca social structure is a complex one; just like humans they have regionally distinct languages and strategies for hunting. Orcas have often been observed to be strategizing new hunting tactics, and teaching those advantageous new techniques to other whales. Alaska fishers claim to be seeing an increasing number of juveniles taught by their elders to snatch fish from fishing vessels.

Inuit have also observed that orcas swimming deeper into the Arctic as a result of polar ice cover melting, have been preying on slower-moving local fauna. Orcas, stated an Inuit interviewed for a 2012 study, would sometimes kill "hundreds" of belugas at one time. "When the killer whales had left the kill site, Inuit would collect the maqtaq (blubber) from the numerous dead belugas."

Making their home in all seven of the world's oceans, orca pods have been witnessed killing other top marine predators, including great white sharks, walruses and leopard seals.

File -- National Post

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