Upsurge Of Jumbo Squid To California’S Coasts

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Posted by on April 18, 2008 at 02:56:05:

What does this mean for fisheries and the ocean? The recent upsurge observed by scientists and fishermen of the Humboldt squid to the waters around Monterey Bay is raising concern. The Humboldt squid (Dosidicus gigas), also referred to as jumbo squid, is named for the Humboldt Current off the coast of S. America, from which they are thought to originate. Their normal range is Mexico to Peru; however they have been migrating out, being seen as far north as Alaska. The concern for California fisheries is whether the new California coastal inhabitants will affect their harvests. Humboldt squid’s diet has been understood to be krill, shrimp, sardines, mollusks, anchovies, lantern fish and other squid, including their own species. However, a recent study on the contents of their stomachs at Long Marine Lab in Santa Cruz has turned up larger and more surprising prey. Digestive remnants such as bird feathers have been found, but it is the presence of species like Pacific hake that has the industry’s attention. Pacific hake, primarily a Northwestern catch, is the largest fishery on the west coast. Current California Pacific hake stocks appear healthy but are suffering in Puget Sound, likely due to over-fishing. Though no evidence has turned up in their stomachs, fishermen are also watching to see if the squid start to target juvenile salmonids.

So what does this mean for other important commercial fisheries in California, namely in Monterey, which has struggled in recent years from low water levels in the major spawning rivers, stricter fishing regulations and low fish populations? "We have no direct evidence the squid is impacting fisheries," said John Field, a fishery Biologist at Long Marine Lab. But, with an increasing population of squid consuming species like rockfish, northern anchovies and Pacific sardines, it is feasible. "You have a new predator on the block that is pretty awesome," said Stanford Biologist William Gilly, who has funding from the California Ocean Protection Council and California Sea Grant to study the squid’s influence on the California Current ecosystem. "They have huge energy requirements and they are starting to eat things that people care about."

A commercially viable fishery themselves, the third largest in Mexico, Humboldt or jumbo squid may be migrating due to ocean climate changes and an alteration in their food web. "There has been an expansion of the environment the squid like," said Gilly. In 1997, the large influx of jumbo squid was proposed to be the result of El Nino. As well, since 1984, oxygen levels taken by CalCOFI off Monterey have decreased by about 20%. Squid are tolerant of this oxygen-minimum zone and lantern fish, a primary staple in the squid’s diet, flourish in such conditions. Another possible reason for their upsurge is a lack of predators. Sperm whales are a predator and their numbers appear to have doubled on the west coast in the past 15 years, but marlin, some tuna, and sharks have decreased, in part due to over-fishing. For additional news articles see: 27 January 2008 Santa Cruz Sentinel article, www.mercurynews.com/centralcoast/ci_8092333; see the 28 January 2008 California Sea Grant Christina Johnson article, www.csgc.ucsd.edu. For more information on Alaskan Pacific hake stocks, please contact John.DeVore@noaa.gov, phone (503) 820-2280.

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