Jumbo squid lurking off the Pacific Northwest coast could threaten salmon runs and signal another change in the oceans brought on by global warming.

The squid, which can reach 7 feet long and weigh up to 110 pounds, are aggressive, thought to hunt in packs, and can move at up to 15 mph. In Mexico, they are known as diablos rojos, or red devils. They reportedly will attack divers when threatened.

No one knows why they started appearing off Washington state and Oregon or how many there are, but scientists and commercial fishermen have found them in their nets every year since 2004 and their numbers are increasing. One ship trawling for Pacific hake captured an estimated 50 tons of the squid in one net haul. Though they usually prefer deep water, 1,000 to 1,500 washed up on the Long Beach Peninsula in southwest Washington in the fall of 2004.

“This is a new phenomenon,” said Jason Phillips, a faculty research assistant at Oregon State University’s Hatfield Marine Science Center in Newport, Ore. A briefing paper from the science center suggested the jumbo squid may already be “well established” in the Pacific Northwest.

Canadian fisheries officials said the jumbo squid were first seen in Northwest waters in the early 1950s.

“But that was a rare event,” said Ken Cooke, head of applied technology for the Canadian Department of Fisheries and Oceans in Nanaimo, B.C. “It’s not rare anymore. They were always thought to be a transient visitor; now it appears they are resident.”

LARGE NUMBERS MIGRATE NORTH, SOUTH

Also known as the Humboldt squid, the animals typically have been found off the coast of Mexico, Central America and Peru. An estimated 10 million squid were living in a 25-square-mile area near the town of Santa Rosalia, Mexico, several years ago.

In the late 1990s they appeared in increasing numbers off the central California coast around Monterey Bay. By 2005, jumbo squid were found as far north as Sitka, Alaska.

“There is no question they have moved north and in pretty large numbers off Washington state and Oregon,” said John Field, a fisheries biologist with the National Oceanic and Atmospheric Administration based in Santa Cruz, Calif., who has studied them.

At the same time the jumbo squid were moving north, they were also moving south along the South American coast. Chilean fishermen used to catch none. Now they are catching 200,000 tons a year, mostly for export to Asia, Field said.

“The fact this is happening in both hemispheres could be a sign it is tied in with global warming,” Field said. “We are trying to piece this all together.”

A paper from the Canadian Department of Fisheries and Oceans concludes the large number of jumbo squid now found between Oregon and Alaska indicates a “profound” change in coastal ecosystems.

OVERFISHING, LOW-OXYGEN WATER SUSPECT

Others have suggested the squid have been able to expand their range because of overfishing of its natural predators, including tuna, sharks and swordfish. At the same time, the population of another of the squid’s predators, sperm whales, has roughly doubled off the West Coast.

The mystery grows more complicated when scientists start talking about a huge bubble of low-oxygen water found in deep water off the west coasts of North and South America that seems to be expanding, perhaps because ocean temperatures are rising. Jumbo squid thrive in the low-oxygen zone. Generally warmer ocean temperatures along the Northwest coast could also be a factor, though jumbo squid can live in cold waters.

“They are the poster child in how to succeed in a changing world,” said William Gilly, a Stanford University biology professor.

Jumbo squid are voracious predators known to dine on krill, lantern fish, shrimp, sardines, rockfish and other squid. They are cannibalistic. Sharp, barbed suckers on their tentacles snare their quarry and drag it to their mouths, where it’s torn to shreds by a baseball-sized beak.

“They are amazing predators,” said Cooke. “They will eat anything and continuously. They don’t have an off-on switch.”

Cooke said jumbo squid can grow an inch or so a day, and they live no more than two years.

FISHERIES COULD BE AFFECTED

The squid’s favorite food might be Pacific hake, a whitefish often used in fish sticks. The Pacific hake fishery is the biggest on the West Coast, and its populations have been declining as the squids’ range has grown.

“Major fisheries could be affected,” said Louis Zeidberg, a Stanford University researcher.

Scientists aren’t sure what impact jumbo squid have had or may have on the dwindling salmon runs of the Pacific Northwest. Zeidberg said there is anecdotal evidence the squid have been eating salmon. Fields said he has not found salmon remains in the stomachs of the more than 500 squid he has dissected.

The squid could be eating the juvenile salmon entering the ocean. But the juveniles stay close to shore, while the squid prefer deeper water off the continental shelf 15 to 50 miles off the coast. Squid have been filmed eating hake, but most salmon are bigger and can swim faster.

Another theory is that as the squid are eating the smaller fish that such marine mammals as seals and sea lion feast on, the marine mammals have been forced to dine on more salmon.

But the most discussed theory focuses on the threat the squid present as salmon school in the ocean and head back to the rivers and streams to spawn.

“They could face a wall of tentacles,” said Zeidberg.

Even if the squid capture only a handful of salmon, the run could be disrupted as the fish scatter.

While much of the research has focused on squid off the California coast, Cooke said scientists are hoping to ramp up studies farther north.

“We don’t have an understanding of this animal at all,” he said.