WASHINGTON — By the end of this year, the world is projected to reach an unheralded but historic milestone: Half of the fish and shellfish consumed by humans will be raised by humans rather than caught in the wild.
Reaching this tipping point is reshaping everything from the oceans to the livelihoods and diets of people across the globe. It has also prompted a new round of scientific and political scrutiny as researchers and public officials examine how aquaculture is affecting the world's environment and seafood supply.
"Hunting and gathering has reached its maximum," said Ronald Hardy, who directs the University of Idaho's Aquaculture Research Institute and coauthored a study on the subject in the Proceedings of the National Academy of Sciences. "We've got to grow more."
The drive to get fish "from egg to plate," as Hardy puts it, has the po-tential to answer a growing demand for seafood worldwide, as well as reduce some of the imports that compose more than 80 percent of the fish and shellfish Americans eat each year. But without technological advances to improve efficiency, it could threaten to wipe out the forage fish that lie at the bottom of the ocean's food chain and potentially contaminate parts of the sea.
And consumers will have to accept that they are eating a different kind of fish from the ones that swim wild: ones that might have eaten unused poultry trimmings, been vaccinated, consumed antibiotics or been selected for certain genetic traits.
Although there is still debate about farming's share of the world fish supply - the United Nations' Food and Agriculture Organization estimates that it stood at 44.3 percent in 2007, whereas the Academy of Sciences study says it will reach over half in a matter of months - no one questions that aquaculture has grown exponentially as the world's wild catch has flattened out. In 1970, farmedfish accounted for 6.3 percent of global seafood supply.
This trend reflects global urbanization - studies show that as more people move to cities, they are consuming more seafood - but it is changing the world's seascape as well. Vessels now venture to the Antarctic Ocean to catch the tiny krill that have sustained penguins and seals there for millennia, and slender poles strung with farmed oysters and seaweed jut out of Japan's once-pristine Matsushima Bay.
Chinese freshwater fish farms are replacing traditional agricultural plots there, according to Karen Seto of the Yale School of Forestry and Environmental Studies, and Nature Conservancy senior scientist Mike Beck said some Chinese bays are so crammed with net pens that they are no longer navigable.
Moreover, fishermen such as Shannon Moore, who catches salmon in Washington state's Puget Sound, worries about how farmed fish's parasites are affecting wild stocks.
"These young wild critters are pretty small, and they can ill afford to have these hitchhikers on them," Moore said, referring to parasites that plague juveniles migratingnear Canadian fish farms.
But aquaculture's proponents suggest that farming represents the best chance of giving people a chance to make a living off the sea. Sebastian Belle, executive director of the Maine Aquaculture Association, noted that three-quarters of his group's members are either current or former commercial fishermen, and although the average age of Mainers with a fishing lease permit is 57, the average for those with a fishfarm permit is 33.
"It's really the next generation of watermen," Belle said.
Jane Lubchenco, who used to write about aquaculture's environmental impacts as an academic before taking the helm of the National Oceanic and Atmospheric Administration, announced this month that her agency will come up with a national policy to address fish farming. "It's important that aquaculture be done in a way that's sustainable," she said.
Farms are expanding in traditional U.S. fishing strongholds, such as New England, the Gulf of Mexico and the Pacific Northwest, and freshwater fish farms continue to operate in states such as Arkansas, Mississippi and Alabama.
Freshwater species such as catfish, trout and tilapia still dominate the nation's farmed fish production, but such niche products as oysters with regional appellations and sustainably raised shrimp and caviar now fetch a premium in the United States.
Still, the United States accounts for just 5 percent of the nation's seafood supply, although the $1.2 billion in annual production is 1.5 percent of the world's total. In 2006, China supplied 62 percent of the world's farmed fish and shellfish, according to the U.N. Food and Agriculture Organization.
Michael Rubino, who directs the National Oceanic and Atmospheric Administration's aquaculture program, said he envisions a time in which the country is "producing seafood from a range of technologies, with wild catch on one side, aquaculture on another, and a whole range in between."
This prospect has set off a flurry of activity and experiments as scientists and entrepreneurs try to resolve the environmental challenges fish farming poses. The biggest one involves a fundamental quandary: One needs to feedmany small fish to bigger fish to produce ones consumers crave.
One-fourth to one-third of the world's fish catch is landed just to produce the fish oil and fish meal that fish, poultry and pig-farming operations demand, depleting stocks of forage fish such as anchovies, sardines and menhaden.
Aquaculture has become more efficient, according to the Academy of Sciences study. In 1995, it took an average of 2.29 pounds of wild fish to produce 2.2 pounds of farmed fish, and in 2007 it took 1.4 pounds to achieve the same result.
The sector's share of global fish-oil and fish-meal supplies has doubled in the past decade as the industry has boomed.
Patricia Majluf, who directs the Center for Environmental Sustainability at Cayetano Herida University in Lima, Peru, watched fleets decimate Peruvian anchovetta stocks in the 1970s and again in the 1990s, setting off an environmental chain reaction in which the area's seabird populations crashed.
"There was no supervision, no control whatsoever," said Majluf, adding that it took a change in governmentin 2006 to institute a more restrained fishing policy that guarantees at least 5 million tons of anchovies remain in the sea to sustain the ecosystem. "Since then, you're seeing this amazing recovery."
"We've got to solve the feed problem," said Stanford University professor Rosamond Naylor, the Academy of Sciences study's lead author. "We've got to come up with an alternative that breaks the connection between aquaculture and wild fishing of forage fish."
Hardy experiments with everything from pulling out corn protein right before the corn is fermented into ethanol to stringing together algae to form the omega-3 fatty acids people expect from their fish.
Rep. Lois Capps, D-Calif., a member of the House Natural Resources Committee, says he plans to introduce legislation in the near future to help establish a national aquaculture policy.
He said the current situation "requires a comprehensive response" from the federal government.
"There are commercial demands; we can't ignore that," Capps said. But she added: "Doing it at all means doing it carefully."
Business, Pages 75, 84 on 09/27/2009