Aquaculture, once a fledgling industry, now accounts for 50 percent of the fish consumed globally, according to a new report by an international team of researchers. And while the industry is more efficient than ever, it is also putting a significant strain on marine resources by consuming large amounts of feed made from wild fish harvested from the sea, the authors conclude. Their findings are published in the Sept. 7 online edition of the Proceedings of the National Academy of Sciences (PNAS).

"Aquaculture is set to reach a landmark in 2009, supplying half of the total fish and shellfish for human consumption," the authors wrote. Between 1995 and 2007, global production of farmed fish nearly tripled in volume, in part because of rising consumer demand for long-chain omega-3 fatty acids. Oily fish, such as salmon, are a major source of these omega-3s, which are effective in reducing the risk of cardiovascular disease, according to the National Institutes of Health.

"The huge expansion is being driven by demand," said lead author Rosamond L. Naylor, a professor of environmental Earth system science at Stanford University and director of the Stanford Program on Food Security and the Environment. "As long as we are a health-conscious population trying to get our most healthy oils from fish, we are going to be demanding more of aquaculture and putting a lot of pressure on marine fisheries to meet that need."

Fishmeal and fish oil

To maximize growth and enhance flavor, aquaculture farms use large quantities of fishmeal and fish oil made from less valuable wild-caught species, including anchoveta and sardine. "With the production of farmed fish eclipsing that of wild fish, another major transition is also underway: Aquaculture's share of global fishmeal and fish oil consumption more than doubled over the past decade to 68 percent and 88 percent, respectively," the authors wrote.

In 2006, aquaculture production was 51.7 million metric tons, and about 20 million metric tons of wild fish were harvested for the production of fishmeal. "It can take up to five pounds of wild fish to produce one pound of salmon, and we eat a lot of salmon," said Naylor, the William Wrigley Senior Fellow at Stanford's Woods Institute for the Environment and Freeman Spogli Institute for International Studies.

One way to make salmon farming more environmentally sustainable is to simply lower the amount of fish oil in the salmon's diet. According to the authors, a mere 4 percent reduction in fish oil would significantly reduce the amount of wild-caught fish needed to produce a pound of salmon – from 5 pounds of wild fish to just 3.9 pounds. In contrast, reducing fishmeal use by 4 percent would have very little environmental impact, they said.

"Reducing the amount of fish oil in the salmon's diet definitely gets you a lot more bang for the buck than reducing the amount of fishmeal," Naylor said. "Our thirst for long-chain omega-3 oils will continue to put a lot of strain on marine ecosystems, unless we develop commercially viable alternatives soon."

Naylor and her co-authors pointed to several fish-feed substitutes currently being investigated, including protein made from grain and livestock byproducts, and long-chain omega-3 oils extracted from single-cell microorganisms and genetically modified land plants. "With appropriate economic and regulatory incentives, the transition toward alternative feedstuffs could accelerate, paving the way for a consensus that aquaculture is aiding the ocean, not depleting it," the authors wrote.

Vegetarian fish

Fishmeal and fish oil are important staples at farms that produce carnivorous fish, including salmon, trout and tuna. But vegetarian species, such as Chinese carp and tilapia, can be raised on feed made from plants instead of wild-caught fish. That's one reason why farm-raised vegetarian fish have long been considered environmentally friendly.

In the early 1990s, vegetarian fish farms began adding small amounts of fishmeal in their feed to increase yields. However, between 1995 and 2007, farmers actually reduced the share of fishmeal in carp diets by 50 percent and in tilapia diets by nearly two-thirds, according to the PNAS report. Nevertheless, in 2007, tilapia and carp farms together consumed more than 12 million metric tons of fishmeal – more than 1.5 times the amount used by shrimp and salmon farms combined.

"Our assumption about farmed tilapia and carp being environmentally friendly turns out to be wrong in aggregate, because the sheer volume is driving up the demand," Naylor said. "Even the small amounts of fishmeal used to raise vegetarian fish add up to a lot on a global scale." Removing fishmeal from the diet of tilapia and carp would have a very positive impact on the marine environment, she added.

Regulating fisheries

On the policy front, Naylor pointed to the 2006 California Sustainable Oceans Act and the proposed National Offshore Aquaculture Act, which call for reductions in the use of fishmeal and fish oil in feeds. She also applauded plans by the National Oceanographic and Atmospheric Administration to develop a comprehensive national policy that addresses fisheries management issues posed by aquaculture. "No matter how much is done from the demand side, it is essential that there be regulation on the supply side as well," Naylor said. "You won't prevent the collapse of anchoveta, sardine and other wild fisheries unless those fisheries are carefully regulated."

Other co-authors of the PNAS study are Ronald W. Hardy, University of Idaho; Dominique P. Bureau and Katheline Hua, University of Guelph (Canada); Alice Chiu, Stanford; Matthew Elliott, Sea Change Management; Anthony P. Farrell and Ian Forster, Centre for Aquaculture and Environmental Research (Canada); Delbert M. Gatlin, Texas A&M University and the Norwegian Centres of Excellence; Rebecca J. Goldburg, Pew Charitable Trusts; and Peter D. Nichols, Commonwealth Scientific and Industrial Research Organisation (Australia).

The PNAS report was supported by the David and Lucile Packard Foundation.

Notices of the demise of Iran’s Green Revolution are premature. Without question, the tyrannical triumvirate — Ayotallah Ali Khamenei, President Mahmoud Ahmadinejad and the Revolutionary Guard — have dealt a crippling blow to the popular movement protesting their electoral coup of June 12.

Thousands of Iranians have been arrested and savagely tortured — from street protesters to election campaign organizers for Mir Hussein Moussavi, the likely victor in that contest. Many are now being forced to “confess” to having been agents of the United States or Britain.

We have seen this play before, not simply in Iran but in other tyrannies that suppressed mass movements for democratic change with massive violence and terror.

But Iran in 2009 is not China in 1989, Burma in 1990 or Belarus in 2006. The crisis in the Islamic Republic has exposed and widened massive cracks within the ruling elite. Such divisions are always a sign of an impending crackup of dictatorship.

Despite the rush to bury Iran’s reformist movement as another lost cause, Iran remains at a possible political tipping point. Democracies around the world have a duty — not simply to themselves, but to their strategic interests — to weigh in. They must not be deterred by threats to shun talks over Iran’s nuclear program.

President Obama has gotten it right by signaling America’s support for peaceful protest, human rights and the rule of law. More explicit language, not to mention action, would only play into the hands of the most cynical and vicious conservative elements in Iran. Moreover, with no diplomatic ties and all but no trade with Iran, there is little more the U.S. could do right now to pressure the regime.

But there are over 100 other democracies in the world. It is time that their voices were heard and their actions felt in Tehran.

Britain shares with the U.S. the handicap of a past history of negative interference in Iran. But Britain has diplomatic and economic ties to the regime, and breaking or suspending those will weaken Ayatollah Khamenei and his reactionary allies.

Moreover, Britain can have a unique kind of impact in Iran: For more than a century, Iranians have believed in the omnipotence of the “British hand” in the affairs of their country. Any indication that Britain is no longer willing to do business with the Islamic regime will hearten the Iranian people and undermine the regime’s aura of invincibility.

Germany, France and Italy are major trading partners with Iran. They have little history of colonial interference in Iranian affairs. Their decision to refuse to recognize the Ahmadinejad regime would have an immense effect. More compelling still would be a similar declaration from the entire Group of 8 at its impending summit.

The smaller and less powerful democracies can also have an impact. It would be preposterous for Iranian hardliners to attribute ulterior strategic motives to actions by the Scandinavian countries or the Netherlands, Ireland, Canada or Slovenia. If a coalition of such countries were to condemn the crackdown, call for a release of political prisoners and demand full respect for human rights — and back up these positions with a downgrading of diplomatic and trade ties — this would send a powerful message to both sides in Iran.

Many democracies around the world, including the above, have diplomatic ties with Iran. It is important that they maintain their embassies in Tehran. But they should now refuse to recognize the legitimacy of Ahmadinejad’s government.

The most powerful coalition of democracies in the world, the 27-member European Union, is now debating whether to withdraw their ambassadors from Tehran in protest over the detention of the British Embassy’s Iranian personnel.

The withdrawal of E.U. ambassadors would send a stunning message to the Iranian hardliners that coups and bloody suppression of peaceful protests carry a heavy price in international standing.

With the simple diplomatic act of denying legitimacy — something nearly all democratic forces in Iran are now asking of the world — the democracies of the world can give a needed boost to the forces of democratic change in Iran and earn the lasting gratitude of a movement that will eventually triumph.