June 17, 2011 | 1
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 first blog post about the trip.
SEA OF CORTEZ—Our group of squid researchers is back for a follow-up expedition to the one we reported on in June 2010. We again have groups from Stanford University, University of Rhode Island and Oregon State University working on our National Science Foundation-supported collaboration focused on the ecology, behavior and physiology of the jumbo (Humboldt) squid, Dosidicus gigas, in the Gulf of California. "Act II" 2011 will feature many of the same characters, both human and non-human, and new visiting players from a number of intuitions. Some of the scenes will be the same as well, but some remain to be revealed – this will be an adaptive expedition. But the protagonist from 2010 will not be making an appearance. El Niño took a curtain call during our 2010 cruise, and during the last year we have been analyzing our data and trying to piece together a story on how this climatic anomaly impacts jumbo squid and the Gulf of California. We’ll try to tell that story first, because it provides the background for many of the thoughts that will guide our efforts this year. We do not yet know what we will find.
At the present time we are onboard the University-National Oceanographic Laboratory System (UNOLS) research vessel RV New Horizon and sailing up the middle of the Gulf of California towards Guaymas, Sonora, our port-of-call where we will pick up the rest of our science party tomorrow afternoon. A not-quite skeleton crew departed San Diego on June 4 and has been steaming full-speed ahead since then.
As we transit, we are assembling a variety of experimental set-ups that we will need to carry out the work we have planned. Weather and seas have been incredibly benign, and today when were finally in the Gulf, the heat and humid stillness has become almost overwhelming. The placid sea revealed turtles, cruising dolphins, curious sea lions, some whales, and seemingly world-record performances by flying fish. At dusk a gentle breeze came up and cooled things down. But it is not a good idea to wish for breezes in this body of water. They will surely come soon enough in force. This is the Gulf of California, and we are home.
El Niño and the distribution of jumbo squid in the Gulf of California: Cruise of June 2010
Between fall of 2009 and late spring of 2010 the southern half of the Gulf of California was affected by an El Niño event in the eastern Pacific Ocean. During this time the sea surface was about 3 degrees Celsius warmer than normal, and warm surface-water reached much greater depths than normal. These are two classic signatures of El Niño. We recorded these changes in collaboration with Lindblad Expeditions and National Geographic Society.)
Another classic effect of El Niño is a decrease in coastal primary productivity (phytoplankton). During El Niño wind-driven upwelling fails to deliver nutrients to the surface, because warm, nutrient-poor water reaches such a great depth. The resulting decrease in phytoplankton has negative impacts on many organisms from zooplankton to whales, including birds, fish and squid.
During our 2010 cruise we started in Guaymas, Sonora, and moved across the Gulf to Santa Rosalia, Baja California Sur, sampling squid by jigging along the way. Although squid were common, they were all unusually small, only about one third of their usual size is this area. There was also no commercial fishing being carried out near Santa Rosalia, another highly unusual situation that had not occurred since the last strong El Niño in 1997-98.
In Santa Rosalia we heard reports that large squid were being caught about 150 miles to the north. Moving north along the Baja coast we continued sampling squid, but again we only caught small animals. Finally we found large squid in the Salsipuedes canal off Bahia San Rafael, south of Bahia Los Angeles. A dozen commercial squid boats from Guaymas were working there. There had never so many squid in this northern region before 2010 and no large-scale commercial fishing.
The abundance of large squid in the north and their total absence in the south suggest that many squid, particularly larger ones, abandoned their normal habitat off Santa Rosalia in 2010 and instead colonized this northern area. The Salsipuedes canal is highly productive, but upwelling of cold, nutrient-rich water is driven by tidal forces rather than by wind. Tidal upwelling continues during El Niño, and this area may act as productive refuge for squid, sardines and other organisms that are negatively impacted by decreased productivity to the south.
El Niño and the size of jumbo squid in the Gulf of California
Although finding only small squid in the Guaymas Basin in June 2010 was unusual, it was even more surprising that many of these animals were fully mature and spawning. A preliminary analysis of age for these squid has revealed a figure of only 5 to 6 months. Thus, these squid would have been born during January-February at the height of the El Niño. Large squid in the north were of mixed maturity states, and small squid were all immature, and this is normal during non-El Niño years in the Guaymas basin. During the last 10 years of sampling squid we have never seen small, mature animals like those in June 1010. The only time that such squid were observed in the Gulf of California was in 1999—after the 1997-98 El Niño
Based on our work from last year, we propose that jumbo squid display at least two adaptive strategies to cope with El Niño. One strategy is moving to another area that is not so impacted. A second strategy is to mature and spawn at an extremely small size. Both strategies would avoid a long future with an uncertain food supply.
Although we have ideas about what happened to the squid in 2010, big squid still have not returned to the Gulf of California, at least according to all the sources we have checked, including commercial fishermen, sports fishermen and scientists. How long it will take big squid to recolonize the areas that were abandoned in conjunction with the 2009-2010 El Niño remains a critical question for all concerned, particularly the local fishermen whose livelihoods depend on this resource.
Our search for some insight into this mystery will start soon. For now, we glide towards Guaymas, everybody busily assembling and fine-tuning their equipment for experiments to be carried out on the cruise.
Images of New Horizon and San Diego skyline courtesy of Ian Wilson, Colorado State University; images of Dolphin, sea lion, gull courtesy of Ted Uyeno, Northern Arizona University; map courtesy of Google Earth, adapted by W. Gilly