GEORGE SUGIHARA
FOOD FOR THOUGHT: Using complexity theory, he has shown that standard fisheries practices produce unstable populations that can boom or bust even when food is abundant.
FISHY ADVICE: That fishers teach their children to throw the little ones back is exactly wrong when it comes to fisheries health, he says.
ON LIVING WITH CHAOS: "Most fisheries management is based on the idea that these systems are stable. Watches are like that. Transistors are like that. But ecosystems are not."
Image: Gary Payne
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When George Sugihara reads about credit crises and federal bailouts, he is inclined to think about sardines—California sardines, to be precise.
A few decades after the Great Depression, the sardine fishery in California was suffering from a similarly devastating collapse. Fishers who had generally landed more than 500,000 tons of sardines annually during the 1930s caught fewer than 5,000 tons during the worst years of the 1950s and 1960s. Whereas a few Cassandras might have warned of trouble in each case, nobody could have predicted exactly when each collapse would come or how severe it would be.
The sardine collapse puzzled fisheries experts. Some blamed overfishing. Others suspected environmental swings—shifting wind patterns or cooling sea-surface temperatures. But nobody could prove either case. Eager to prevent another such collapse, California set up a monitoring system that has been collecting data on sardine larvae for the past 50 years. Sugihara, a mathematician and theoretical ecologist at the Scripps Institution of Oceanography in La Jolla, Calif., analyzed that data and came to a surprising conclusion: both potential explanations of the sardine collapse were wrong.
His conclusion, in a study published in Nature in 2006, was that the problem was the harvesting of too many big fish. Fishing boats were leaving behind a population of almost all juveniles. Sugihara showed that mathematically such populations are unstable. A slight nudge can create a boom—or a catastrophic collapse.
Imagine, Sugihara says, a 500-pound fish in an aquarium. Feed it more, and it gets fatter. Feed it less, and it gets thinner. The population (of one) is stable. But put 1,000 half-pound fish in that aquarium, and food shortages could result in the deaths of hundreds, because the small fry have less stored body fat—and therefore cannot ride out a short famine. Food abundance does not necessarily mean all the fish get bigger, either; it could encourage reproduction and a population boom—which might in turn overwhelm the food supply and lead to another bust. It is an unstable system. “That’s the reality of fisheries, of economies, of a lot of natural systems,” Sugihara says. The recent history of the sardine fishery illustrates that instability: fishers along the West Coast from Canada to Mexico are now harvesting a million tons of sardines annually.
But this instability is not understood by people who run fisheries, Sugihara insists. By law they manage fisheries for “maximum yield.” The notion that such a maximum yield exists implies that fish grow at an equilibrium rate and that the harvest can be adjusted in accordance with that growth to keep yields stable. In contrast, Sugihara sees fisheries as a complex, chaotic system, akin to financial networks. They are so alike that the global financial giant Deutsche Bank lured Sugihara away from academia for a time; there, from 1996 to 2001, he successfully used the analytical techniques that he would later call on for his sardine work to make short-term predictions about market fluctuations.
Although both marine ecosystems and financial markets might look random, Sugihara explains, they are not. That means making short-term predictions is possible, as it is with the weather. The eminent ecologist Robert M. May of the University of Oxford calls that predictability “the flip side of chaos.” May oversaw Sugihara’s doctoral work at Princeton University when he was a visiting professor there and is now a frequent collaborator. “George was one of the first to see this as a recipe for making predictions,” he says.
Sugihara’s research comes at a time of enormous concern about the future of the world’s fisheries. Perhaps the most alarming report came in late 2006, when Boris Worm, a marine conservation ecologist at Dalhousie University in Nova Scotia, reported in Science that for 29 percent of currently fished species, the catch had dropped to less than 10 percent of the historical maximum. If the trends continue, he reported, all fisheries around the globe will collapse by 2048.
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8 Comments
Add CommentI wonder what fishing technology could be used to ensure catches are only of youger fish? Sidney Holt
Reply | Report Abuse | Link to thisPerhaps the answer is to put randomness back into fishing : If we banned fish shoal detection technology, fishermen would go back to trawling around at random. So this would ensure that some shoals of both young and old fish would survive to maintain populations. As captains would certainly object that this would waste engine fuel, an alternative answer would be to enforce no-go zones to reintroduce a little chaos into the system?
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Could be possible with a bit of thought. Doing hook & line baitboating near floating aggregation devices in the eastern tropical pacific would tend to take the smaller yellowfin, and without bycatch. It would also tend to be more labor-intensive and less fuel-intensive, important since fuel will now get scarcer forever. Mexico's Cantarell oilfield is crashing and Mexico won't be a petroleum exporter 5 years from now.
Reply | Report Abuse | Link to thisAdmittedly, this is based on the peculiarities of one species, but perhaps learning and taking advantage of such behavioral quirks is what it will take.
Instead of banning areas to fish or making more laws or complicated bycatch rules ... why not tell fishermen to only keep fish of certain relative sizes - those around the 50 - 75 percentile range (maybe - don't know if this is a good number to capture a proper fish maturity). Then, spend the money to educate everyone as to why this needs to be so. The result is at the markets, public opinion would keep marketers and the public from trading in certain sizes.
Reply | Report Abuse | Link to thisIn the ocean, the small fry will be left to grow and the largest will be left to give stability - and enough numbers in the "catchable" range will slip by to become big fish.
Now, this is sustained with public opinion and not with tax dollars to patrol and check up on fishers. And it doesn't rely on fishers only since they can only sell certain sizes.
Will there still be a "black market"? Sure, but it will not be illegal, so if a few of the "wrong" sizes are sold, that will satisfy that small demand (at a higher price - but most wont deal in those fish due to the greater uncertainty over the ability to sell.
Restricting catches of small fish has one major drawback. Fishermen throw the small fish overboard, where they simply die because they have suffered from lack of oxygen for so long. Using bigger net meshes is better, as the small fish can theoretically escape. But as fish have no fear of nets, do they try to escape through the mesh from the accustomed safety of the shoal?
Reply | Report Abuse | Link to thisEnforcing quotas is unpopular worldwide, but it does work in Norway...
The article by Paul Raeburn in your February issue explains how mathematician George Sugihara discovered that fishing big as opposed to small fish is bad. Ive been advocating that perspective in publications for decades*, based on my former experience as Chief of Marine Resources for FAO, especially for Mediterranean fisheries which since the second WW have been dominated by targeted harvesting of juvenile bottom fish. Few of these survive to maturity, but then these are/were apparently protected by refugia, which for the Mediterranean are rocky, untrawlable areas along the narrow shelf edge. The EC is now getting the Mediterranean message, and considering closure of areas in the NE Atlantic where large cod congregate (I mean mature cod I doubt that any large cod are left in the North Sea). This strategy has worked (up to a point) in the Mediterranean. Until the last decade, fisheries for juveniles despite a lack of quota control, mostly seemed sustainable. That they are apparently no longer so, is probably less because of targeting juveniles, but due to the combined influence of relentless fishing, land runoff and habitat destruction; all described in the Mediterranean fisheries literature.
Reply | Report Abuse | Link to thisSincerely,
John F. Caddy, Aprilia, Italy.
The article by Paul Raeburn in your February issue explains how mathematician George Sugihara ‘discovered’ that fishing big as opposed to small fish is bad. I’ve been advocating that perspective in publications for decades*, based on my former experience as Chief of Marine Resources for FAO, especially for Mediterranean fisheries which since the second WW have been dominated by targeted harvesting of juvenile bottom fish. Few of these survive to maturity, but then these are/were apparently protected by ‘refugia’, which for the Mediterranean are rocky, untrawlable areas along the narrow shelf edge. The EC is now getting the Mediterranean message, and considering closure of areas in the NE Atlantic where ‘large’ cod congregate (I mean mature cod – I doubt that any large cod are left in the North Sea). This strategy has worked (up to a point) in the Mediterranean - until the last decade, fisheries for juveniles despite a lack of quota control, mostly seemed sustainable. That they are apparently no longer so, is probably less because of targeting juveniles, but due to the combined influence of relentless fishing, land runoff and habitat destruction; all described in the Mediterranean fisheries literature.
Reply | Report Abuse | Link to thisSincerely,
John F. Caddy, Aprilia, Italy.