October 05, 2009
Monday

BREMERTON, Wash. - The Humboldt squid, a voracious predator that can grow to 100 pounds in two years, has captured the attention of researchers all along the West Coast.

Thousands of the mysterious creatures appeared suddenly off the Washington Coast and Strait of Juan de Fuca this summer. Some researchers say the aggressive animal, which has generally stayed south of California, has the potential to disrupt local ecosystems in more northern areas.

Why the squid arrived here and how long it will stay are just two of the questions researchers would like to answer. Since the squid eat just about anything -- including young salmon -- fisheries managers are looking for answers that can help them protect vulnerable species.

This week, Greg Bargmann, a biologist with the Washington Department of Fish and Wildlife, and William Gilly, a Stanford University researcher, went about 20 miles offshore of Westport to catch a few dozen squid. Stomach contents were examined in about 30 animals. Another 24 were implanted with acoustic tags, which will allow researchers to track their movements through a network of acoustic receivers up and down the West Coast, including Canada.

"We saw plenty of squid in a couple hours," Bargmann said. "Every time we found a school of anchovy, we would try fishing around it. And every single one resulted in good catches of squid."

One of the basic questions to be answered is whether the squid that people are seeing have risen up out of deep water or have migrated from another area. The squid show a wide tolerance for temperature. The prevailing idea is that they were moving around in search of food when they stumbled upon schools of fish -- which, in turn, can be influenced by warmer temperatures.

"One of the reasons we wanted to tag these squid," Bargmann said, "was to see if these same ones are detected off the coast of Oregon or California."

John Field, a researcher with NOAA Fisheries in California, said the squid have been found to favor a position in deep water just above the low-oxygen zone. Among their prey are certain kinds of fish that stay in low-oxygen waters during the day, then move into more shallow waters at night.

Low-oxygen waters may offer the squid refuge from predators, including tuna and sharks that cannot tolerate the low-oxygen conditions. Their sudden success in more northern waters may be related to a lower predation, since tuna and sharks are more rare off the West Coast of North America.

Humboldt squid are rarely seen north of California, where they have been seen for the past 10 years. Before that, they were last seen off California in the 1930s, when they were eating so many fish that they were declared a nuisance.

"They are well known for having sporadic outbreaks," Field said.

There is some evidence, he noted, that they may be responding to increased upwelling of nutrients related to El Nino conditions. Upwelling brings nutrients up from the depths, feeding an extensive food web.

These Humboldt squid -- named for the South American Humboldt Current -- are well established in the southern hemisphere. Chile maintains a commercial fishery that catches and sells about 700,000 tons of the creatures each year. Worldwide, commerce in Humboldt squid is greater than any other species of cephalopod, which includes all species of shellfish.

Humboldt squid can grow to seven feet long. They are believed to live no longer than three years, and some researchers say two. They appear to spawn together in masses. While some biologists believe they die soon after spawning, others say they can spawn more than once.

Bargmann said it is even possible that different populations respond differently to given conditions. Nobody knows for sure.

"These animals can grow from nothing to over 100 pounds in 36 months," Bargmann said. "That is a tremendous amount of growth."

The squid are known to follow schools of coho salmon, and some fisherman have faced the disappointment of catching a fish, only to have it grabbed by a squid on the way to the boat.

The squid are also eating smaller fish that serve as prey for salmon and other fish. Because each squid eats so much and seems to catch many kinds of fish with ease, researchers who study them are worried that they may decimate a given fish population before moving on.

"I would like to know if this is going to be a regular occurrence," said Bargmann. "Do we need to start thinking about the impacts of these squid?"

If they are seen early next year, Bargmann said he may call for the opening of a commercial fishery for the big squid, which can be sold for a good price on the international market.

Humboldt squid:

Alias: Jumbo squid or diablo rojo (red devil)

Size: Up to 7 feet and 100 pounds

Home: Historically, south of California, though they started to show up regularly off northern California about 10 years ago. This year, large numbers were seen in Oregon, Washington and British Columbia.

Social Structure: This is one of the few types of squid that live in groups, called shoals.

Food: They generally eat small animals such as krill and small fish, though they may eat larger fish. When food is scarce, they are known to eat smaller members of their own kind.

Predators: Sperm whales, sharks, tuna, fishermen.

Reproduction: Mating behavior is unknown but their ability to change colors may play a role in communication. Eggs have never been seen by researchers, but females probably hide their eggs in rocks, as other squid do.

Source:

squid-world.com

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