Biology professor William Gilly and student researchers recently managed to identify the El Niño phenomenon as the reason for changes in the Humboldt squid’s spawning habits.
The Humboldt squid — which resides in the Sea of Cortez — has been spawning at a much younger age and smaller size than in past years. Gilly began his research in 2009, inspired to find the missing large squid in the Gulf of California.
“What we found instead was small squid all over the Gulf, but the biggest surprise was that these squids were mature and spawning,” Gilly said.
The El Niño phenomenon, a climate pattern that occurs every five years, causes warm water to be pushed down from the surface to an unusually great depth. Warm water from the Eastern Tropical Pacific gets pushed north into temperate latitude, causing temperature change. El Niño triggers a coastal upwelling process, which is driven by wind and the rotation of the earth. The upwelling of normally cool, nutrient-rich water brings warm, nutrient-poor “tropical” water to the surface. The phytoplankton’s productivity, as a result, suffers. The squid, which eat phytoplankton, are thus impacted.
“Squid can move to an area of tidal upwelling, which remains productive during an El Niño condition, and continue on their merry, giant squid lifestyle and live to spawn when they are a year and a half old,” Gilly said.
The study found that Humboldt squid are maturing earlier in response to exaggerated, changing environmental conditions. The number of squid was found to be lower than in past years. Another change Gilly’s research team discovered was that the squid were not as concentrated in one region. Gilly attributed this recent change to the squid’s ability to quickly adapt to new conditions. The effects of these adaptations, however, are difficult to determine at this early stage.
“It’s as if a population of humans started reproducing at age three,” Gilly said. “Whether this is good or bad for the squid, is not something that I can easily grasp. It’s just the way it is — but presumably this radical change in lifestyle serves some purpose and has been selected for by evolution.”
The study found that the shift in lifestyle, in response to El Niño, is circumstantial. Among the surprises was the speed at which the shift occurred — the changes in squid living patterns occurred between September 2009 and May 2010, less than one generation’s time for squid. The timeframe correlated exactly with El Niño, leading to the conclusion that El Niño caused the change in squid lifestyle patterns.
“To our knowledge, the only times small mature squid have been reported from the Gulf of California have been after the 1997-98 El Niño and the 2009-10 El Niño Modok.” Gilly said. “These squid are not on the small tail-end of a normal distribution or anything like that — they form a completely distinct size class.”
The study’s implications for the future of the Humboldt squid population remain unknown. Gilly and his research team have been looking to changes in squid patterns during the 1997-1998 El Niño period to formulate predictions.
“It took two years for large squid to return to the traditional fishing grounds in large enough numbers to support commercial fishing,” Gilly said. “We’re coming up on two years, so next summer may show a return to normal [patterns]. All we can do now is try to track things and see where they go.”
Gilly’s research indicated the important role of global warming in the El Niño phenomenon. The current changes from global warming could exacerbate the impact of El Niño, resulting in a potentially irreversible change in the size and living patterns of the Humboldt squid.
“As long-term warming continues and temperate California waters become more tropical-like, one might expect a northward progression of the smaller form of Humboldt squid,” Gilly said. “What’s intriguing about our observations is that the switch from jumbo to small Humboldt squid at maturity can happen so fast — and that it can be triggered by a discrete event like El Niño.”