These stories about the Humboldt squid invasion off the California coast keep turning up — the latest from the San Jose Mercury News is broadly informative, and even cites a fresh new paper in PNAS. The work correlates the depth range of the squid with that of the Pacific hake, and also shows a rough correlation between the squid population and hake declines over a number of years. This suggests that maybe “invasion” isn’t the right word anymore: the Humboldts are new California residents.
The present situation off central California appears to be that
a physiologically tolerant species with a fast generation time
has moved into a new area during a period of substantial climatic,
oceanographic, and ecological changes. The occupation has
lasted through multiple generations of the invading species, which indicates a sustained population rather than a relict one
or multiple invasions. The geographical range of the invader now
extensively overlaps that of a large commercially valuable fish
stock. If this trend continues, top-down forcing could have a
major impact on the most abundant commercial groundfish
population off the west coast of North America. A similar
pattern may also be taking place in the Southern Hemisphere.
As a past resident of both Oregon and Washington states, which have experienced some irritating invasions of Californians, I have to say … now you know what if feels like, nyah nyah.
The authors also suggest that we may not be able to pin this one on global warming. The overfishing of swordfish and tuna have reduced the effects of these predators of the squid, and now they’re experiencing a bit of a population boom, one that means other animals on the food chain are experiencing some new pressures. Ecology is never simple, is it?
The newspaper article reports that people are fishing for the Humboldt squid, and it’s turning up on restaurant menus in the Monterey area (anyone try it? How is it?), and there are charter boats that will take you squid fishing. If I ever get a couple of days in Monterey, I think I’d like to try that.
(hat tip to Zeno)
Zeidberg LD, Robison BH (2007) Invasive range expansion by the Humboldt squid, Dosidicus gigas, in the eastern North Pacific. Proc Nat Acad Sci USA. July 23, 2007.