Sunday, October 25, 2009

Species Migration: Humboldt squid - a hungry predator moves northward

When we think of "invasive species," one might think of the example of the Lionfish that has invaded Florida waters due to being initially released from a home aquarium. Or perhaps algae, seaweeds or other parasites or bacteria that get discharged from the bilges of freighters and tankers, thousands of miles away from its point of origin.

But there is also species migration, wherein a species enters into a new region sometimes because of a change in its typical prey diet or because of a change in its environment - such as temperature change.

Both factors enter into the migration that has occurred over the past several years by the Humboldt Squid - a large and particularly voracious predator.

I have had the pleasure of working on several potential projects with Scott Cassell, CEO of the Undersea Voyager Project and one of the leading experts on Humboldt Squid, a distinction borne out of his having spent more time face-to-face with these creatures than anyone else. Scott has made the rounds of many news programs to express his concern with the recent regional habitat changes of the Humboldt Squid and what it represents to the balance of the marine and terrestrial ecosystems and even the safety of humans.

The Humboldt Squid is a large deep water predator, typically found along the west coast of Mexico and South America. But over the past several years, there have been two major changes that have impacted this animal. One factor: the overfishing of shallower-water predators that either feed on the squid or on the squid's food supply - thereby establishing territorial boundaries based on depth. Without these shallower predators, the squid can and has begun to roam in search of food. The second factor: increasing water temperatures which have allowed the squid to migrate up the coast and as far north as Washington and Alaska. Another possible variable is that changing temperature and acidification upwardly expands the low-oxygen water column that the squid seems to favor.

Moving into shallower water is of concern to Scott as that can increase the likelihood of a Humboldt Squid encountering curious divers or even swimmers. This past summer, divers were regularly seeing Humboldt Squid during night dives at La Jolla, CA, near San Diego. Whether on the hunt or simply being curious, these animals are not to be taken lightly - they have powerful suckers, a beak that can break bones, and the speed and strength to drag a diver around in the depths.

The squid's migration northward is also of concern because of its ability to disrupt the food supply for other animals. They have been cited by some as being responsible, along with commercial fishing, for a reduction in the northwest population of salmon. And this can impact other animals that depend on this particular food source. As an example, Grizzly Bears count on the fat-rich salmon for building up their stores to survive the winter.

There have been other invasive species migrations due to changing ocean temperatures; in particular, several jellyfish species that have moved into both Northern Atlantic and Pacific waters and doing considerable damage to commercial fishing or aquaculture operations - their stinging tentacles spoil the catch.

But the Humboldt Squid is just not someone you want to bump into in the middle of the night. He's just doing what evolution has taught him to do, but this is one critter than can really give you the willies!

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