Posted by: The ocean update | April 9, 2015

Fish-stealing whales take bite out of black cod harvest in Gulf of Alaska (USA)

In this May 25, 2005, photo provided by the Southeast Alaska Sperm Whale Avoidance Project, a sperm whale swims near a fishing boat in Alaska. Sperm whales may be using the sounds of fishing boat engines as underwater "dinner bells" to home in on valuable sablefish, or black cod, hooked by longlines in the Gulf of Alaska.Heather Vukelic / Southeast Alaska Sperm Whale Avoidance Project / AP

In this May 25, 2005, photo provided by the Southeast Alaska Sperm Whale Avoidance Project, a sperm whale swims near a fishing boat in Alaska. Sperm whales may be using the sounds of fishing boat engines as underwater “dinner bells” to home in on valuable sablefish, or black cod, hooked by longlines in the Gulf of Alaska.Heather Vukelic / Southeast Alaska Sperm Whale Avoidance Project / AP

April 9th, 2015 (Hal Bernton). How do you keep a whale from grabbing the fish off your lines ?

Do you put out decoy buoys to try to trick them? Do you blast heavy metal from the deck of your boat to annoy them, or run for hours in hopes of ditching them ?

All these tactics — and more — have been tried by frustrated fishermen working the Gulf of Alaska, where sperm and killer whales skillfully strip high-value black cod from miles of baited lines.

“Sometimes, you will catch 3,000 pounds. Then the whales will show up, and you will get nothing,” said Paul Clampitt, a fishermen who is a 30-year veteran of the black-cod harvests off Alaska.

The problem has grown so bad that many Gulf of Alaska longliners favor a radical move : They want to abandon their traditional hooks and lines in favor of baited steel traps — akin to crab pots — that would protect their catch from whales.

A federal fishery council meeting this week in Anchorage is scheduled to vote on whether to give the green light for a shift to using the pots.

The frequent presence of whales on the fishing grounds is a marked turnaround from the 1970s, when veteran Alaska longliners say they were an infrequent sight.

It is part of a broader global phenomenon, with longline fishermen off Washington state, Chile, Australia, Hawaii and other places reporting the same loss of hooked fish to whales.

Off Alaska, Japanese fishermen in the mid-20th century reported conflicts with killer whales in the Bering Sea, followed by reports from U.S. longline fishermen. By the late 1980s, whale encounters spread to the Gulf of Alaska.

Today, sperm whales in eastern Gulf waters and killer whales in the west are an increasingly common and unwelcome sight around longline boats.

As fishermen haul their lines up from the sea bottom, the propeller gives off distinctive acoustics as the engine slips in and out of gear. This appears to act like an underwater dinner bell to the two species of whales, according to researchers.

Sometimes, fishermen report more than a dozen killer whales, including calves, around boats as a crew retrieves longline gear. The whales may grab an entire fish off a hook, or leave behind a few remains.

“They’ll bite just light enough that the body comes off, and the head and guts are left for you,” said Pat McBride, a Homer, Alaska, fisherman who longlined for decades in the Gulf of Alaska and the Aleutian Islands.

Sometimes, only the lips remain on the hooks.

Researchers have also identified a group of 115 sperm whales that work the fishermen’s lines off Southeast Alaska. Those whales, which appear to be mature males, can reach the size of school buses and be larger than some of the boats.

They were the target of intensive hunts that — harpoon strike by harpoon strike — severely reduced their populations by the time commercial harvests ended in the late 20th century. The federal government still lists them as endangered, but scientists believe their population is on the rise.

Fishermen say the sperm whales don’t travel as fast as the killer whales and are easier to shake. But they can edge right up to the boats.

“They are not afraid of you at all. I could literally step right off a boat and onto a sperm whale. That’s how close they are,” Clampitt said.

But fishermen say that once sperm whales home in on a fisherman’s gear, they can take plenty of fish.

Sometimes they bite the black cod off the hooks. They also may grab the longline to create tension that causes some fish to come unhooked. This was first captured by researchers in an underwater video taken in 2006 at a depth of more than 300 feet.

“We thought they were just mostly biting the fish off. It really opened our eyes,” said Jan Straley, a University of Alaska Southeast marine biologist. “We realized that empty hooks could mean a whale was responsible.”

While it’s hard to know exact numbers, federal surveys put the total losses at under 10 percent of the annual harvest of the more than 360 Gulf of Alaska vessels that fish for black cod.

On occasion, fishermen report much larger percentages of their catch lost to whales.

One study found that killer whales can reduce the catch by an average 65 percent.

“It may be sporadic when the whales show up. But when they do, it can be very costly,” said Megan Peterson, an Alaska marine biologist who conducted the study.

Fishermen say they also lose money and fishing time trying to avoid the whales.

“Sometimes you will fish for seven days, and you just can’t shake them,” said Buck Laukitis, a longline fisherman based in Homer. “It’s probably the most frustrating thing we’ve experienced as fishermen. It’s worse than bad weather.”

Researchers have experimented with different types of devices that aim broadband signals at the longliners in hopes of fending off the whales. They also tried to foil the whale’s acoustic ability to target fish by injecting bubbles into the water and putting beads on the longlines.

Whales often figure out ways around the deterrents.

Some fishermen have found it makes sense to try to fish as part of a larger fleet working a relatively small area. That way, there’s a greater chance that whales will target someone else. Some fishermen deliberately run past another boat to pass off the whales.

“It’s kind of dirty pool,” said Clampitt.

The proposed rule change for the federal harvest would give the option to use pot traps that lure in the black cod with ample amounts of bait.

There have been some strong opponents. Many small-boat fishermen believe their vessels are ill-suited to fish with pots, and that the cost of the transition is too high. They also fear prime fishing spots will be claimed by the pots, so they will be unable to lay down their longlines without snagging other gear.

“I feel a pot fleet would eventually displace the smaller longline boats. That would not be good for the boats, nor the communities those boats base from,” wrote Terry Perensovich, of Sitka, Alaska, in a March 22 letter to the federal council. “I guess I would rather see a whale on the Horizon (sic) than a Pot boat.”

Clampitt said it would cost him $200,000 to switch to pots on his 90-foot boat, and he wouldn’t make the move right away. But he probably will eventually.

“If you can find a gear that is clean and whales can’t get fish, then why wouldn’t you do it?” Clampitt said. “We’re looking to the future.”

What remains to be seen is whether whales could figure out a way to open a pot.

“I wouldn’t put anything past a sperm whale,” said Straley, the marine biologist. “They are the cleverest animals I’ve ever worked with.”

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