Could Warming Lead to Squid Boom?

Nov. 15, 2004 — -- As evidence mounts of possible global warming and overfishing, there may be a flip side to the dire news: an abundance of calamari.

Research has shown that many squid, octopuses and other sucker-bearing members of the cephalopod family don't appear to be too troubled by a minor increase in ocean temperature. In fact, when it's a little warmer, some thrive. Plus, as the fishing industry captures more and more of the animals' predators, such as tuna, cephalopods may see their niche expand.

"The good news is they taste great," said John Forsythe, an expert on the creatures from the National Resource Center for Cephalopods near Houston. "They're pure protein and they have no bones."

A study released last week said in the past half-century, average yearly temperatures in Alaska and Siberia have risen by about 3.6 degrees to 5.4 degrees Fahrenheit, while winters in Alaska and western Canada warmed by about 5 degrees to 7 degrees. Scientists say this evidence points to an overall trend of warming temperatures and waters worldwide.

It's uncertain how such warming could affect different animal species, but some believe that cephalopods will thrive.

"For shallow water species, warming temperatures is likely to expand their range and speed up their growth," said George Jackson, a squid expert at the University of Tasmania.

Ballooning in the Heat

Research has shown that even a slight increase in water temperature can make the animals balloon in size. This is because their digestive enzymes work faster when warm.

"For cephalopods, temperature appears to be an accelerator," said Forsythe.

Jackson recently estimated the total body mass of the animals has already exceeded that of humans on Earth. Past research has suggested that sperm whales alone consume more than 100 million tons of squid every year. Jackson reasons if that estimate just covers squid eaten by one predator species, then their total mass must exceed that of humans, which represent half of 1 percent of the total biomass on Earth, according to the World Wildlife Foundation.

Meanwhile, fishing rates of another predator, tuna, have doubled from 2 million to 4 million tons a year since 1994, which means more squid may have escaped being eaten. Couple these factors with slightly warmer waters and you have a boom.

Anecdotal evidence has hinted at the success of the animals. Fishermen off the coast of New Zealand and Australia have been pulling up more squid in their nets in recent years. And on the West Coast of the United States, from Southern California to Alaska's shores, a series of widespread sightings and beachings of the enormous Humboldt squid has scientists puzzled and pointing to possible warmer temperatures in these waters.

Humboldt squid, also known as flying jumbo squid, can reach 7 feet to 15 feet in length and weigh as much as 100 pounds. Their growth rate is also astounding. A young squid 2 millimeters in length can grow to a meter in a single year.

"That's like a human baby growing to the size of a whale in one year," said William Gilly, a biologist at Stanford University's Hopkins Marine Station in Pacific Grove, Calif., who has been studying the species.

Over the past few months, the voracious animals with probing arms and tentacles have appeared as far north as the Alaskan coast. Gilly chalks up their northern appearances to a bump in warming in these areas and the animal's flexible biology.

"The species seems to be pretty adaptable to temperature, so if temperature opens up new niches, they just move in," he said. "They're not picky."

Not All Squid Are Alike

But other squid experts point out not all cephalopods may do well in warming conditions. Steve O'Shea, a senior research fellow at Auckland University in New Zealand, says squid that reside mostly in surface waters may be more flexible than those that hover in the ocean's permanently chilly deep depths. And cephalopods that hang out in colder regions of the globe, like the colossal squid (the largest known squid that has been found off the coast of Antarctica), may be more vulnerable to temperature change.

"A warming of the oceans could also result in the demise of cold-water, deep-sea species of squid," he said.

He adds that fishing isn't only affecting fish species. Cephalopods are often snagged in nets and trawlers who drag nets on the ocean floor can destroy clusters of their eggs.

"Seven species of octopus and squid in New Zealand waters are already considered extinct or seriously impacted by deep sea fisheries," he said. "This is the opposite side of the coin."

Jackson says despite the uncertainty about colder-water cephalopods, he has no doubt that a shift is under way.

"We're replacing one ecosystem -- fish -- with another -- cephalopods," he said. "There's no way of knowing what impact that will have."

Forsythe suggests one consequence could be a change in the American palate.

"In North America, squid aren't that popular yet," he said. "But when fish are $10 a pound and squid are $4 a pound, people will start to say 'Hmm, wonder if I can find a good recipe for that?'

"I think that's inevitable."