Thriving orcas preying on fishing vessels
COMMERCIAL BOATS STRIPPED OF CATCH BY KILLER WHALES AND SPERM WHALES
The orcas will wait all day for fishermen to accumulate a catch of halibut, and then deftly rob them blind. They will relentlessly stalk 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, co-owner of the F/ V Augustine in Washington State.
Like many fisher men, Clampitt tried electronic noisemakers on the Augustine to ward off the animals, but the orcas simply got used to them.
“It became a dinner bell,” he said.
John McHenry, owner of the F/ V Seymour, described or ca 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 Anchorage Daily News outlined instances of aggressive orcas harassing boats — even refusing to leave after a desperate skipper cut the engine and drifted for 18 hours.
“It’s gotten completely out of control,” Alaska fisherman Jay Hebert told the newspaper.
Fishing lines are also being pillaged by sperm whales, the large square-headed whale best known as the white whale in Moby Dick.
“Since 1997, reports of depredation have increased dramatically,” noted a report by the Southeast Alaska Sperm Whale Avoidance Project.
A remarkable 2006 video by the Avoidance Project captured one of the 50,000- kg whales delicately shaking fish loose from a line.
After a particularly heavy assault by sperm whales, fishermen are known to pull up lines in which up to 90 per cent of the catch has disappeared or been mangled.
Some skippers will try to outrun a hovering pod, but the time and fuel needed to dodge a persistent gang of whales can wreak havoc on a trip’s profitability.
“I’ ve had the same sperm whale follow me 70 miles ,” Michael Offer man with the F/ V Kristiana told the National Post by email.
While fishing boats all across Alaska have reported harassment by orcas, the worst incidents all seem to be occurring in the Bering Strait, the body of water separating western Alaska from Russia.
In a 2014 study of Alaska fisheries, orcas snatching fish from lines were estimated to cost boats as much as US$ 500 per day. Compare that to Uruguay, where a 2015 study of boats using similar fishing techniques found that “the presence of killer whales in the fishing ground seems not to affect the catch per unit effort.”
Whale predation on fishing boats is increasing in part due to a rebound of North Pacific whale populations brought about by the 1980s moratorium on commercial whaling.
Up until then, cod and halibut fishermen were moving among whale populations that had been decimated by whaling fleets — and where survivors had learned to fear the approach of a boat engine.
“When I started fishing in the early ’80s, when we saw a whale it was an event,” said Clampitt. “Now, they circle the boat.”
This is not the first time that Alaskan waters have been thrown into disorder by the changing appetites of killer whales. In the 1990s, researchers found that orca predation was responsible for a sudden collapse in Pacific sea otter populations not seen since the animals were driven to near-extinction by the fur trade.
Orcas have remarkably complex social structures, with regionally distinct languages and hunting strategies. They’re also innovative: orcas have frequently been observed inventing new hunting tactics and then teaching them to others.
In April, orcas off Monterey Bay, Calif., killed four grey whale calves over eight days in what was described as an unpreced- ented “killing spree” by local media. Biologists attributed the episode to a single nine-member pod of orcas that had become unusually skilled at hunting grey whales.
Similarly, harassed Alaska fishers say they are seeing increased numbers of juvenile whales — a possible sign that adult orcas are teaching their young to seek out fishing vessels for their meals.
McHenry described pulling in lines cleared of fish, only to notice that some fish near the end of the line were 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,” he said.
The only surefire way to ward off a pod of hungry orcas is pot fishing. Rather than fishing with exposed lines, boats convert to “pots,” essentially giant traps.
It’s not a cheap fix. A pot conversion on the F/ V Augustine, for instance, cost US$ 600,000. And while the method works for now, Clampitt suspects that orcas might innovate a way around them.
“It’s possible at some point they might start hitting the pot,” he said.
Alaska fishing boats wouldn’t be the only northerners to be seeing more orcas lately. As polar ice cover melts, it has allowed pods of orcas to swim ever deeper i nto the Arctic Ocean, where Inuit have observed the newcomers preying on the slow-moving local fauna.
An Inuit interviewee for a 2012 study on the phenomenon said orcas would sometimes kill “hundreds” of belugas at a time.
“When the killer whales had left the kill site, Inuit would collect the maqtaq ( blubber) from the numerous dead belugas,” it noted.
Aside from humans, orcas are the world’s top apex marine predator. Found in all seven of the world’s oceans, pods of orcas have been seen handily killing other top marine predators, including great white sharks, walruses and leopard seals.
Unlike any other of t he world’s large hunters, however, orcas have spared humans. Although captive orcas have caused human deaths, to date there is no record of a human ever being killed by an orca in the wild.
In fact, the only widely accepted account of an orca attack on a human occurred in 1972, when California surfer Hans Kretschmer suffered an orca bite to his left thigh.