This article was published in Scientific American’s former blog network and reflects the views of the author, not necessarily those of Scientific American
Editor's Note: William Gilly, a professor of biology at Stanford University's Hopkins Marine Station, embarked on new expedition this month to study jumbo squid in the Gulf of California on the National Science Foundation–funded research vessel New Horizon. This is his ninth blog post about the trip.
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SEA OF CORTEZ—Every day the winds blew, and an undersea factory silently hummed along, welling up millions of tons of cold, nutrient-rich seawater from the depths to replace the water at the surface that had been pushed out to sea by the wind and the invisible hand of the rotating earth. In the Baja California port of Santa Rosalia on the Gulf of California, this system continued from mid-spring to late fall, and the ensuing richness supported the vast numbers of Humboldt squid that drove the ecology of this region, both in the sea and on shore. On a typical summer night several hundred lights glittered on the dark waters off shore—one car dome lightbulb on each small panga carrying two or three fishermen and, when they were finished, a ton of squid. From the grade leading down the mountain into town it appeared that the city was literally on the Gulf rather than next to it.
In the winter, the winds reversed from northward to southward, a seasonal clock as regular as the length of the day. When this happened, the squid sensed something was changing as the surface water grew colder. And then the squid moved away, not all at once but gradually over the course of a few months until only a few stragglers were left behind. They would stay in the area all winter, but most of the other squid would make the 80-mile migration across the Gulf to the mainland coast where the city of Guaymas is located. Winter winds now drove the productivity conveyor that fed the squid on this coast, and that would continue until mid-spring. Here, too, the squid were fished with intensity, so people cared. When the north wind battered back the south wind in the spring, the nomadic squid would return to Santa Rosalia and summertime bounty.
This cycle has replayed yearly since 2001. Hurricanes have come and gone, but the squid shrugged them off, perhaps altering their behavior or distribution for a week or two, delaying a migration a bit, but the cycle continued. There was a simple, natural order to the system that benefitted both squid and fishermen. Everyone understood the rules and invested accordingly.
In 2010 this wind-driven bubble burst. A mild El Niño event in the second half of 2009 grew quite strong as the year ended, pushing warm surface water in the Gulf down to a depth much greater than normal. This warm surface-water is typically low in nutrients, so when wind-driven upwelling occurs, it does not bring the rich soup of nutrients to the surface. Phytoplankton, the base of marine food webs, needs these nutrients, and the loss of primary productivity by phytoplankton impacts nearly everything else in the sea from tiny fishes to blue whales and seabirds. So when El Niño comes knocking, it is a signal of potentially hard times ahead, perhaps for a year or more. If you are a fast-growing annual species, like a Humboldt squid, this presents a problem.
Humans have learned to ignore El Niño at great peril. NOAA constantly monitors the state of El Niño and informs the public on a monthly basis, because a lot of investment, jobs and lives are impacted by the changes in weather patterns associated with this powerful environmental perturbation. Although squid don't have the internet, they do appear to have a set of remarkable strategies for dealing with the uncertainties associated with a developing El Niño and impending collapse. In many ways it seems analogous to the bursting of an economic bubble and the inevitable slow recovery. Maybe they can teach us something.
The primary reaction of squid is simple—abandon the highly productive areas that are fueled by wind-driven upwelling, because these areas may not be able to support their numbers for an unknown time. Where do the squid go? Again, a simple answer—to an area that is buffered from the effects of El Niño. Our work over the last two years has shown us that there are at least two such buffered areas in the Gulf of California, and the squid take advantage of both.
In the more straightforward strategy, the squid move a hundred miles or more to the north into the "Midriff Islands" archipelago. Here, halfway up the Gulf, tidal currents funnel through deep channels and lead to upwelling driven not by wind but by tidal energy. The area is extremely productive and is well known for immense seabird rookeries on some of the islands such as Isla Rasa, where nearly all of the planet's Heermann's gulls and elegant terns come to breed.
Isla Rasa lies just to the east of the Salsipuedes canal, the only location where we have found big Humboldt squid since May 2010. But relocating here requires some readjustment. There is no midwater oxygen minimum zone (OMZ) here, normally the favored daytime feeding ground in the Guaymas Basin, and there is a correspondingly lower number of myctophid lantern fish, the favored prey. Instead, squid here consume krill and an assortment of small fishes. In this krill-dominated ecosystem the squid are well fed, but their diet is not very diverse. What might be the associated price? At this point we don't know. Perhaps there is an inherent danger to living in a place that lacks diversity, but evidently this gamble is better than facing the potential collapse associated with El Niño. So the big squid are here, having liquidated their diverse portfolios at the first sign of trouble and shifting everything to a money market account.
A second strategy is remarkable. Instead of seeking an area with maintained productivity, the squid seemingly take the opposite approach and move offshore to inhabit the blue-water pelagic environment of the open sea. Although this world is much less productive than the favored shelf closer to shore, it is not so dependent on wind-driven upwelling, and is therefore less impacted by El Niño. In this case, the OMZ and its myctophids are still there, but the density of prey may be low lower. Bounty is traded for security, but in addition to changing habitats, the squid accelerate their maturation and reproduce at a very small size when they are only six months old (rather than a year or more) —one pound versus twenty or thirty. In effect, any penalty for living in the less productive, but more dependable, pelagic environment is minimized by passing the problem on to a new generation. A small squid will produce fewer offspring, but with 5 million eggs in a small squid versus 25 million in a large one, the numbers are immense either way. This more aggressive strategy seems to almost be a metamorphosis, a radical change in morphology (size anyway) and life history. Perhaps in economic terms, it would be analogous to moving assets from a blue-chip portfolio to high-risk new ventures during a depression with the hope that a few will take off as markets evolve during the inevitably unpredictable recovery.
We have learned something about how the squid responded quickly and decisively as species to El Niño, but recovery is another matter. It seems to be painfully slow. Productivity and oceanographic conditions are back to normal, but the squid are still in the two response modes outlined above—after two or three generations. But our work leads to some ideas. Small, mature squid were significantly bigger this year than last—about 40 cm average mantle length versus 30 cm. Each generation may be getting larger, but the squid are still far below the 'normal' size at maturity of 70 cm or so. Fishermen in Santa Rosalia began fishing a few weeks ago for the first time in a year, but the squid are small. It takes a lot of time to catch a ton of 2-pound squid, so the fishermen remain troubled. But if the squid are returning en masse to the traditional fishing grounds, it is probably an important step in the recovery process. Squid recolonizing this productive area may have more to eat, remain here longer, grow larger and reproduce at an older age. Whether size at maturity jumps in one generation to the full 70 cm or by accretion remains to be seen. A similar recovery process may occur independently in other regions previously known to support large numbers of squid, and possibly new areas as well. Judging by our recent experience on the open Guaymas Basin, there are a lot of squid ready for near-shore bounty.
And what about the big squid that have retained their one-year life cycle in the Salsipuedes region? Will they remain in large numbers in this region and establish a new population center as the traditional fishing areas in the Guaymas Basin rebuild? To our knowledge, there have never been so many squid in this region during the years before El Niño, but the area had not been very well studied in this regard. In July 2006 we explored this region a bit and found big squid, and squid that we tagged in the northern Guaymas Basin near San Pedro Martir moved into the area near Isla Tiburon. We don't really know more than that. To our knowledge, commercial squid fishing in this region was virtually non-existent here before 2010 when it boomed.
In the end, it seems that both asset-reallocation strategies of the squid may succeed. Although the fishermen worry about the lack of squid, recovery seems to be on the way. It is quite possible that the squid population in the Gulf may actually benefit from this El Niño through a more permanent expansion into the Salsipuedes region. And the vast numbers of small squid that we encountered in the Guaymas Basin may fuel a population explosion there. Analysis of our acoustic data will shed a lot of light on these questions and others posed above.
An adaptive strategy to cope with a system-wide perturbation as powerful as El Niño that involves multiple generations and may actually benefit the species seems incredible. I have often said that if you were to design the perfectly adaptable organism, you could easily end up with something like a Humboldt squid—flexible diet, environmental tolerance to temperature and oxygen changes, ability to migrate rapidly, and so forth. But the ability to capitalize on an environmental anomaly that can greatly decrease productivity with bottom-up effects that ripple throughout the food web is something else. Making good from bad is something that we need to learn more about, and perhaps economics theorists can learn from the strategies of the Humboldt squid. I am not the first to suggest such a trajectory—check the fascinating article "Ecology for Bankers" by Robert May, Simon Levin and George Sugihara in Nature, Vol. 451, p. 893 (2008).
Things are what you make of them, and everything is connected. I am reminded of the non-teleological thinking espoused by Ed Ricketts and John Steinbeck in Sea of Cortez (1941) — "That Zeitgeist operates everywhere, and there is no escape from it. Again, this is not to be considered good or bad."
Images:
Squid Migrations in Gulf of California: Adapted from cited sources by W. Gilly
Temperature profiles before and during El Nino: W. Gilly, data from project funded by National Geographic Committee on Research and Exploration
ENSO Advisory: Adapted from NOAA website by W. Gilly
Heermann's gull, elegant terns and Isla Rasa breeding area: Nancy Burnett, May 2004