California Squid Invasion Threatening "Fish Stick" Species
Richard A. Lovett
for National Geographic News
|July 27, 2007|
A species of 100-pound (45-kilogram) predatory squid previously confined to more tropical climates has taken up residence in coastal California waters, scientists say.
And the invasion of Humboldt squid seems to be making a noticeable dent in the local population of hake, experts note in a new study.
Hake, also known as Pacific whiting, is used to make imitation crab, fish sticks, and other minced-fish products.
Scientists noted a potential threat to hake fisheries when an unusual influx of Humboldt squid along the Pacific coast received widespread media attention in the spring.
For the latest study, published this week in the online edition of the Proceedings of the National Academy of Sciences, researchers examined video from submersible dives in Monterey Bay spanning 16 years (see a California map).
They discovered that the squid have been steadily abundant in the region since 2002.
"A top predator has moved in," said study co-author Bruce Robison, a researcher at the Monterey Bay Aquarium Research Institute in Moss Landing.
"This hardly ever happens in terrestrial or marine habitats. Usually, if you get an invading species, it's a snail or crab or something like that."
And the squid's sustained presence, the scientists note, coincides with a documented hake decline.
Squid vs. Tuna
Humboldt squid, also called jumbo squid, are voracious hunters with razor-sharp beaks and powerful tentacles.
"They are amazing animals," Robison said. "They are big and aggressive and often hunt in packs."
Traditionally the squid have been found mostly in the warm waters of Mexico's Gulf of California (see a Mexico map).
Before 1997, the underwater videos revealed no Humboldt sightings in Monterey Bay, Robison said.
Large numbers of squid appeared in the 1990s when El Niño weather events brought warm water up from the tropics. Then the squid disappeared again, except for occasional stragglers.
In 2002 they reappeared and have been abundant ever since.
In addition to moving to California coasts, Robison said, the squid appear to be moving southward into the waters off Chile.
Robison thinks the squid are expanding from their normal range because of declining tuna populations.
Historically, he said, the squid and tuna competed for the same prey. In addition, tuna ate baby squid.
But heavy fishing for tuna and other predatory fish is allowing the squid to flourish.
When El Niño currents brought the squid north, Robison added, they found an environment where their predators, such as sharks, were also on the decline.
"They're here to stay," Robison said. "We know they're reproducing. We see little ones."
But, except for their ecological impacts, he added, the squid pose no threat to people.
"There are a couple of odd stories," he said, "but I don't think they're any threat at all."
William Hanshumaker is a researcher at the Hatfield Marine Science Center in Newport, Oregon.
He said that fishers have been finding Humboldt squid at least as far north as the Columbia River, where he believes the squid are hunting sardines. The river forms much of the border between Oregon and Washington State before emptying into the Pacific (see map).
Furthermore, he said, Oregon has seen numerous beachings of dying squid.
One possibility is that the squid are being killed by a toxin called domoic acid produced by certain marine plankton.
The toxin works its way up the food chain when sardines eat the plankton and squid eat the sardines.
The entire situation reveals how strongly different parts of the oceans are linked, said study co-author Louis Zeidberg of Stanford University.
"[You] could consider the entire Pacific as one ecosystem," he said. "Changes you cause in the tropics can ultimately have an effect all the way to the [temperate] regions."
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