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Squid studies: Into the heart of squid country–or at least where it should be

The views expressed are those of the author and are not necessarily those of Scientific American.


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map of gulf of california and gilly's squid research cruise routeEditor’s Note: Marine biologist William Gilly is on an expedition to study Humboldt squid on the University-National Oceanographic Laboratory System research vessel New Horizon in the Gulf of California. He and other scientists are learning about the giant squid, their biology and ecology on this National Science Foundation-funded expedition. This is his second blog post about the trip.

GULF OF CALIFORNIA—Days 1-3 Guaymas to Isla Tortuga to Santa Rosalia to Punta San Carlos: On this first two-week leg, our group will be catching small Humboldt squid, about 12 inches long, and keeping them alive for a day or two in a cold life-support system. This will provide a supply of animals in good condition to carry out behavioral experiments designed to reveal how strong swimming and escape responses (all by jet propulsion) are impacted by the cold, hypoxic conditions of the OMZ (Oxygen Minimum Zone) where we know the squid spend most of their daytime hours. Meanwhile, Brad Seibel’s group from the University of Rhode Island will be carrying out experiments with live animals in sealed tanks to measure respiration rates and carrying out midwater trawls to characterize the squid’s prey field. And Kelly Benoit-Bird’s group from Oregon State University will be more or less constantly sampling acoustic data as the ship plows along at a steady 4 or 5 knots—slow to get anyplace far away, but good for seeing squid and their prey with sound.

squid life support cooler on gilly nsf squid research expedition cruiseBrad and Kelly were both able to get most of their equipment set up before the start of the cruise in Guaymas on June 3. But we were not so lucky, so all of days one and two and much of day three were spent setting up. There were two major tasks. First item of business was a squid life-support system—a giant cooler holding a six-pack of squid in individual plastic tubes, each plumbed with flow-through, recirculated cold water. The idea is to isolate squid to prevent attacks and to chill them down to lower their metabolism. This device is itself an experiment, and so far it is working pretty well and keeps small squid in good condition for at least 24 hours. A second major effort was setting up for experiments. Everything was new and untested, and suffice it to say that the experience has been a devilish exercise in MacGyverism. We continue to tweak this and that, add another little piece of something or other, and slowly the whole set up started coming together in its cozy little space. There are so many details to get right—and always one more thing to go wrong. More later on these experiments.

During this time we have crossed the Gulf from Guaymas to Isla Tortuga, then to Isla San Marcos and Santa Rosalia and finally north to Punta San Carlos. We typically jig for squid at sunset and at selected spots during the acoustic transects, both day and night. We’ve been catching small squid and testing them in our life-support system and experimental setup, studying them in Brad’s respirometry experiments, tabulating their size and sexual maturity, collecting stomachs to analyze diet, and saving statoliths to determine age back in the lab. Statoliths are tiny calcium-carbonate crystals found inside capsules in the squid’s head, and they are like the otoliths of fish with growth rings that can be counted like those of a tree. What has been perplexing, just as it was during our May expedition several hundred miles to the south, is the utter lack of big Humboldt squid. The area around Santa Rosalia is normally loaded with big squid this time of year, and the commercial season should be in full swing. In a typical year there are about 200 small pangas, each with two or three fishermen jigging squid with hand-lines. Each panga brings in about a ton of squid on a good night, and total landings for June average about 3,500 tons over the last five years.

santa rosalina squid processing plant picture from gilly nsf squid research expedition cruiseWhen we passed Santa Rosalia this time there were no pangas on the water at all—except for the two that delivered what must have been the town’s entire supply of Kola Loka (Mexican crazy glue).* I desperately needed this for our lab experiments and didn’t have any, because it was confiscated by TSA in my checked luggage when I flew to Guaymas. We made some calls to local fishermen with whom we had worked in the past, and within an hour we had not one but two bags of glue—for a steep price of course. At any rate, the fishermen told us that only small squid were around the area and that the only fishing was far to the north, near Bahia Los Angeles. While this is a major inconvenience for our research party, I wonder about the economic impacts on the local fishermen and their families. Not only are there hundreds of fishermen out of work, but many of their wives work at local squid processing and freezing plants. With no fishing, what do these folks do? It must be a hard time in the town.

daytime trawler on gilly nsf squid research expedition cruise in gulf of californiaDuring our jigging stops there have been only small squid from Guaymas to Santa Rosalia, and they again were mostly sexually mature—just like those we found far to the south off Topolobampo on the Holistic Biology cruise in early May. This is abnormal for the Guaymas Basin—small squid are almost always immature, at least during the 10 years we have been studying this area. But here they are, inhabiting an area that should be full of much larger squid. And there is plenty of food here—both the trawls and acoustic surveys have revealed an abundant supply of myctophid lanternfish, the most common prey eaten by large Humboldt squid in these waters in other years.

At Punta San Carlos, north of Santa Rosalia, we finally caught squid that were somewhat bigger, though still quite small. But what was interesting about these specimens is that they were much less mature than the smaller animals to the south. As we progress north, there seems to be an increase in squid size and a decrease in maturity state. This has made us stop and think and speculate.

The only time that small, mature squid were found in the Guaymas Basin, at least during the time we have been working here, was after the 1997-98 El Nino. Unai Markaida of the Colegio de la Frontera Sur, Campeche, described these animals and analyzed a few statoliths that suggested the squid had matured at a younger age than normal. Did these animals grow up during a warm phase with inadequate food and simply mature earlier to allow spawning? A small squid has fewer eggs than a large one, but some offspring is probably better than none. Or did the squid move into the Gulf from tropical Pacific waters, where Humboldt squid are well known to be smaller when mature? In either case, the lack of big squid in their usual haunts in the Guaymas Basin was also noted after the 1997-98 El Nino. There are clearly some strong similarities here.

small humboldt squid on gilly nsf squid research expedition cruise in gulf of californiaPerhaps at the end of these three days we are in a transition zone between waters that were impacted by the El Nino-like winter and now harbor small, mature squid and more northern waters that are inhabited by the big squid that are being commercially fished. Did the large squid simply migrate to cooler waters and leave an ecological vacuum that is filled by smaller squid? What happens when conditions return to normal? Do all of the big squid return to their usual habitat and find it filled with growing competitors? Do some big squid remain in the newly invaded territory and occupy it until the next climatic anomaly and then make another move to a new location? After an anomaly like this, do you end up with two relatively stable population-centers for Humboldt squid?

As we leave the oddly mature, little squid behind in the waters to the south that have been warmed for the last five months by the El Nino-like winter, I find myself trying to extrapolate what we are seeing here to what is going on elsewhere. By traveling this path from the land of little squid to big, we may get some clues as to how Dosidicus appears to leap-frog from one location to another in association with El Nino’s or other climatic anomalies—not only in the Gulf but along the coasts of California, Oregon, Washington and British Columbia. The land of little squid is falling behind us, but it may well hold secrets that will let us look into the future. That’s the hope at the end of a long day.

 


Map of first three days’s journey courtesy of W. Gilly; image of chilled squid life-support system with separate squid (to prevent them from attacking each other) courtesy of W. Gilly; image of workers at a Santa Rosalia squid processing plant in 2003 courtesy of W. Gilly; image of set up for a daytime mid-water (350-meter) trawl where lanternfish were detected courtesy of W. Gilly; image of mature 30-centimeter female squid (with bright orange structures in tail that contain ripe eggs ready for spawining) courtesy of C. Salinas; video of squid fishermen off Santa Rosalina in 2002 courtesy of W. Gilly

*Erratum (6/18/10): This sentence was changed after publication to correct the spelling of Kola Loka.

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