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Jumbo Squid Invading Eastern Pacific

Stefan Lovgren
for National Geographic News
March 30, 2007
 
Flotillas of jumbo squid are invading the length of the eastern Pacific Ocean, and the voracious predators may be upsetting ocean ecosystems and threatening fisheries, scientists warn.

At their largest, jumbo, or Humboldt, squid (Dosidicus gigas) can extend to six feet (two meters) in length and weigh more than 100 pounds (45 kilograms) each.

The squid have earned the nickname "red devils" for their powerful arms and tentacles, razor-sharp beaks, and insatiable appetites. (Related: "Researchers Shed Light on Mysterious Jumbo Squid" [July 18, 2003].)

The animals were already known to exist in large concentrations in Mexico's Sea of Cortez, or Gulf of California (see Mexico map). Scientists estimate that more than ten million squid may be living in a 25-square-mile (65-square-kilometer) area near the town of Santa Rosalia.

But now the squid also seem to have entrenched themselves in the waters along California's coast.

And, perhaps most significantly, the squid's range has expanded both northward and southward to places they haven't ever been seen before—Alaska and southern Chile.

Scientists say the growing numbers of squid are playing an increasingly significant role in the ocean's ecosystems.

Voracious and opportunistic predators, the squid move in schools of more than a thousand and consume vast quantities of fish. At the same time, the squid serve as prey for sperm whales, mako sharks, and other top predators. (Related story: "Jumbo Squid, Sperm Whale Study Reveals How the Giant Creatures Feed, Hunt" [March 12, 2007].)

"Anything that is so abundant and eats so much is bound to have an impact" on its environment, said William Gilly, a biologist at Stanford University's Hopkins Marine Station in Pacific Grove, California. Gilly has studied the squid for decades.

Mystery Migration

The large number of squid seen today off the California coast isn't unprecedented. The squid were abundant there in the 1930s before mysteriously vanishing. They reappeared in the 1970s and were seen in great numbers again in the 1990s.

But in the past few years the predators have spread to entirely new areas. Jumbo squid now clog waters off Oregon, Washington State, and Alaska to the north and have been spotted near the southern tip of South America.

Signs of the squid's newfound fortunes are also increasing on land.

Mysterious mass strandings occurred a couple of years ago along the U.S. West Coast. And in Canada's British Columbia, wolves on outer island beaches have been seen gnawing on squid carcasses.

"It does seem like it's an expansion of range, rather than a relocation," said John Field, a research fisheries biologist with the National Oceanic and Atmospheric Administration (NOAA) in Santa Cruz, California.

Scientists don't know exactly why this migration is occurring, but they believe the squid are constantly on the prowl for ample supplies of food. Because the animals are so large, an area must be dense with prey to support a stable population.

"I don't think a large number of squid could survive year-round in one place or the other, because they would deplete it," Gilly, the Stanford biologist, said.

Scientists also suspect that global warming may play a part in the migrations.

"These high-turnover animals with really high metabolisms are the kinds of animals that you would expect to respond first and respond more to long-term warming trends," Field, the NOAA scientist, said.

"The fact that this is happening in both hemispheres to me really points to a physical mechanism, a climate-related mechanism."

Voracious Eaters

A fishing industry targeting the jumbo squid has flourished in recent years as the animals' numbers have grown.

Hundreds of skiff fishers depart Santa Rosalia every night during the summer. They use multipronged lures and monofilament lines to haul up squid by hand.

The fishery there processes a hundred thousand tons of squid annually, most of it going to Asian markets.

A huge squid-fishing industry has also been established in central Chile.

But there the squid invasion has led to a decrease in the population of commercially valuable hake fish.

That worries California fishers, who fear the squid invasion may soon cut into the area's fish stocks.

To find out what the squid are eating, Field has for the past two years examined the stomach contents of about 500 animals.

"We see that the most frequently occurring prey item that they eat is Pacific hake, and that's troubling because that's one of the biggest fisheries on the West Coast," he said.

The squid are also chowing down on anchovies, sardines, market squid, and smaller rockfish.

"Those are things that humans catch and exploit and eat," Field said.

In addition, fishers complain that jumbo squid harm their catch by attacking or damaging fish caught on lines or in commercial gear.

Winners and Losers

Field, however, points out that the increasing numbers of squid can have positive consequences as well.

"They're eating a lot of things, but they can also be food for a lot of things," he said. "Some animals are winning, others are probably losing. Who's to say how the final balance will tally out?"

The squid invasion has been a boon to some recreational-fishing businesses, which take clients out for squid fishing in the winter, when there's not much else to reel in.

"It's a really fun animal to catch," Field said.

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