This photo provided by AquaBounty Technologies shows two same-age salmon, a genetically modified salmon, rear, and a non-genetically modified salmon, foreground. (AP/AquaBounty Technologies) 
 
 After years of review and endless controversy, the Food and Drug Administration on Thursday approved the nation's first genetically altered animal -- a salmon engineered to grow twice as fast as its natural counterpart. 
 
 AquAdvantage, produced by Massachusetts-based AquaBounty, is an Atlantic salmon that contains a growth hormone from a Chinook salmon and has been given a gene from the ocean pout, an eel-like fish. The result is a fish that is large enough for consumption in about a year and a half, rather than the typical three years. 
 
 Food-safety activists, environmental groups and the salmon fishing industry, not to mention lawmakers from Alaska, have long opposed the approval of the fish -- which they derisively refer to as "Frankenfish" -- and have argued that its existence could open the door to a broad range of potentially unsafe genetically modified animal foods. Knowing an FDA approval was likely, critics have in recent years won commitments from some of the nation's most recognizable chains — including Whole Foods, Trader Joe’s and Target — to not sell the fish. 
 
 [A new method against genetically modified salmon: Get retailers to refuse to sell it] 
 
 The FDA said Thursday that its decision was "based on sound science and a comprehensive review," and that regulators are confident that the genetically altered fish is as safe to eat as a normal Atlantic salmon, with no discernible difference in its nutritional value. Officials noted that the agency held meetings, combed through thousands of public comments and conducted scientific and environmental assessments about the AquaBounty fish before finally approving it. 
 
 "All of that took time," said Laura Epstein, a senior policy analyst in the FDA's center for veterinary medicine. "As with many products that are the first of their kind, we're very careful to be sure we're getting everything right." 
 
 Salmon fishermen and environmental activists have raised concerns about the havoc that could occur if any of AquaBounty's engineered salmon made it into ocean waters and mated with wild Atlantic salmon -- a scenario they say could have unpredictable impacts and lead to the decimation of wild populations. AquaBounty has said its fish are all female and sterile, making it impossible for them to breed with other salmon, even if they somehow were to escape their land-locked production facilities. The company argues its fish actually could reduce pressure on wild fish stocks and prevent the overfishing of Atlantic salmon. 
 
 The FDA said Thursday it will require the AquaBounty salmon to be raised only in land-based, contained tanks in two specific facilities in Canada and Panama, and that it will conduct regular inspections. The approval also doesn't allow the salmon to be bred or raised in the United States for now, though FDA officials said the company could apply to have other production sites approved in the future. 
 
 Critics have argued that an FDA approval of AquaBounty’s salmon could open the floodgates for other genetically engineered animals, each with its own health and environmental concerns. 
 
 "It was a flawed and irresponsible approval ... It sets a very dangerous precedent, given our federal government agencies are ill-equipped to handle genetically engineered animals," said Dana Perls, food and technology campaigner at Friends of the Earth, an international network of environmental organizations that has vehemently fought AquaBounty's efforts. "I think it is a grave mistake we will come to regret." 
 
 [Genetically altered salmon are safe, FDA says] 
 
 Perls said her group and others would continue to try to undermine the market for the fish. "It’s clear: People don’t want to eat it," she said. "We’re going to continue to work with grocery stores and retailers to continue to listen to consumers who don’t want to eat this under-studied, unlabeled GMO fish." 
 
 Rep. Don Young (R-Alaska) has long opposed the AquaBounty fish, saying that its existence would threaten a mainstay industry of his state. He repeatedly has pushed for delays in the FDA approval process, telling the Post in a 2012 interview that he hoped such hurdles eventually would "break that company." 
 
 "This harebrained decision goes to show that our federal agencies are incapable of using common sense," Young said in a statement Thursday. "By embarking on this science experiment, the FDA ignores fundamental risk questions related to our wild fish species and food safety." 
 
 Others welcomed the FDA approval Thursday, none more than the company that has spent two decades developing genetically engineered salmon. "We're thrilled," AquaBounty chief executive Ron Stotish said when reached on his cell phone early Thursday. "We think this is good for science, we think it's good for aquaculture, we think it's good for consumers." 
 
 Stotish took over at the helm in 2008 at AquaBounty, which he said now employees 21 people, and is acutely aware of the fierce opposition among many activists to the firm's genetically engineered salmon. But he said he hopes to win over critics in time. 
 
 "We hope they understand that we understand their concerns. And we've developed a product that mitigates many of the concerns they share and we share," he said. "I hope people take the time to consider the fact that we are an environmentally sustainable product, and that this might actually be a better way to grow salmon ... We hope people consider it on its merits." 
 
 Another issue certain to remain controversial as the genetically engineered salmon moves closer to U.S. dinner tables: Labeling. 
 
 The FDA said Thursday that it can require additional labeling of genetically engineered foods only if "there is a material difference -- such as a different nutritional profile" between the genetically engineered food and its natural counterpart. In the case of the AquaAdvantage salmon, the FDA found no such differences. Thus, the agency won't require a special label, despite the outcry from consumer and health advocates who say that Americans should know if the salmon they are buying has been genetically altered. 
 
 On a conference call with reporters Thursday, FDA officials were asked how consumers eventually would be able to discern between the AquaBounty salmon and any other salmon in the grocery aisle. "[Looking for] 'wild caught' salmon would be one way you could ensure you are not eating genetically engineered salmon," said Larisa Rudenko, senior adviser for biotechnology in the agency's center for veterinary medicine. 
 
 Greg Jaffe, director of biotechnology at the advocacy group Center for Science in the Public Interest, said Thursday's approval is unlikely to impact U.S. consumers, at least in the short term. Even when AquaBounty cranks up its production to full capacity, he said, the hundreds of tons of genetically engineered salmon it could produce annually will amount to a tiny fraction of the massive market for salmon in the United States. 
 
 "It’s not going to be on the shelf tomorrow," said Jaffe, who agrees with the FDA that the genetically engineered salmon would be perfectly safe to eat. "This is not something you have to try hard to avoid. It's actually going to be hard to find." 
 
 This post has been updated. 
 
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 For more health news, you can sign up for our weekly newsletter here. ||||| Government regulators moved a big step closer on Friday to allowing the first genetically engineered animal — a fast-growing salmon — to enter the nation’s food supply. 
 
 The Food and Drug Administration said it had concluded that the salmon would have “no significant impact” on the environment. The agency also said the salmon was “as safe as food from conventional Atlantic salmon.” While the agency’s draft environmental assessment will be open to public comment for 60 days, it seems likely that the salmon will be approved, though that could still be months away. 
 
 The environmental assessment is dated May 4. It is unclear why it took until now for it to be released, but supporters of the salmon say they believe it is because the Obama administration was afraid of an unfavorable consumer reaction before the election in November. 
 
 Environmental and consumer groups quickly criticized the federal agency’s conclusions. 
 
 “The G.E. salmon has no socially redeeming value,” Andrew Kimbrell, executive director of the Center for Food Safety, a Washington advocacy group opposed to farm biotechnology, said in a statement. “It’s bad for the consumer, bad for the salmon industry and bad for the environment. F.D.A.’s decision is premature and misguided.” 
 
 But the decision was long in coming. AquaBounty Technologies, the company that developed the salmon, has been trying to win approval for more than a decade. 
 
 “We’re encouraged by this,” Ronald Stotish, the chief executive of AquaBounty, said on Friday. However, he added, “We’re not so foolish as to be wildly enthusiastic” that Friday’s action will definitely lead to approval. Among other things, some members of Congress have tried to block the agency from approving the fish. 
 
 The AquAdvantage salmon, as it is called, is an Atlantic salmon that contains a growth hormone gene from the Chinook salmon and a genetic switch from the ocean pout, an eel-like creature. The switch keeps the gene on so that the salmon produces growth hormone year round, rather than only during warm weather. The fish reach market weight in about 18 months instead of three years. 
 
 The F.D.A. tentatively concluded in September 2010 that the salmon would be safe to eat and for the environment. A committee of outside advisers, while finding some shortcomings in the analysis, did not contradict those conclusions in general. 
 
 The agency then embarked on a more detailed environmental analysis that has now come to the same conclusions. 
 
 The main concern addressed was whether the genetically engineered salmon could escape and establish themselves in the wild, with detrimental environmental consequences. The larger salmon, for instance, could conceivably outcompete wild Atlantic salmon for food or mates. 
 
 The agency said the chance this would happen was “extremely remote.” It said the salmon would be raised in inland tanks with multiple barriers to escape. Even if some fish did escape, the nearby bodies of water would be too hot or salty for their survival. And reproduction would be unlikely because the fish would be sterilized, though the sterilization technique is not foolproof. 
 
 The agency also said that approval of the salmon would have no effect on endangered species, including wild Atlantic salmon. The National Marine Fisheries Service and the Fish and Wildlife Service did not disagree. 
 
 AquaBounty produces its eggs at a facility in Prince Edward Island, Canada. The eggs are shipped to the highlands of Panama, where the fish are grown to market weight. 
 
 The federal agency said that other facilities for growing the salmon would require separate approvals. It also noted that it did not assess how the salmon would affect the environment in Panama and Canada, only in the United States. 
 
 Opponents said that the agency should do a more complete environmental impact statement. They also said that not enough samples were studied to conclude that the fish would be safe to eat. 
 
 Scientists and companies working on animal biotechnology had complained that the failure to approve the salmon was discouraging investment in the industry. 
 
 An article in Slate earlier this week said the White House had been delaying release of the environmental assessment for political reasons, violating the Obama administration’s pledge to make decisions based on science. The environmental assessment was released soon afterward. 
 
 An agency spokesman declined to comment on the delay. He said it was not possible to predict when a final decision on the salmon would be made. 
 
 The F.D.A. is likely to take weeks or months to analyze the comments it receives. Even if it then affirms the conclusions released Friday, that would be a decision that a bigger environmental impact statement is not needed. The agency would still have to take a separate step to approve the salmon for introduction into the food supply, although it is thought there are no other important issues outstanding. 
 
 Mr. Stotish of AquaBounty said that if the approval came early next year, some salmon could reach American dinner plates late next year. But quantities would be limited by the small capacity in Panama. AquaBounty hopes to sell eggs to other fish farms that would grow larger quantities of salmon, but that is likely to take a few more years. 
 
 AquaBounty has argued that the faster growth of its fish makes it feasible to rear them in inland tanks rather than ocean pens, reducing the environmental impact. “That allows us not to disturb the oceans whatsoever,” said Elliot Entis, the founder of AquaBounty. 
 
 Mr. Entis, who no longer works for the company, has formed a new company to rear the salmon in the United States. 
 
 AquaBounty, which is based in Maynard, Mass., nearly ran out of money waiting for the salmon to be approved. 
 
 Kakha Bendukidze, an investor from the nation of Georgia who owned nearly half the company’s stock, sold his holdings in October to Intrexon, an American company. Intrexon, which is offering to buy the rest of AquaBounty, is providing it with a $500,000 loan. 
 
 Intrexon is working on synthetic biology, which is sort of a souped-up form of genetic engineering. It is not clear yet how it plans to apply that technology to AquaBounty’s fish.
– The FDA made history Thursday when, for the first time ever, it approved a genetically altered animal for human consumption, the Washington Post reports. After two decades of what the FDA calls "exhaustive and rigorous scientific review" the AquAdvantage salmon will be hitting supermarket seafood cases. According to ABC News, the AquAdvantage is an Atlantic salmon with a Chinook salmon growth hormone that allows it to grow all year and a gene from the eel-like ocean pout to activate that growth hormone. Basically this means the AquAdvantage will be big enough to eat in a year and a half instead of the three years required for a normal Atlantic salmon. The AquAdvantage is a "game changer"—nutritious food that's environmentally responsible, says Ron Stotish, CEO of AquaBounty, which makes the genetically altered salmon. The Post reports the approval of the AquAdvantage was opposed by everyone from food-safety activists to the salmon fishing industry. "I think it is a grave mistake we will come to regret," says one environmental group representative. Opponents call the AquAdvantage a "frankenfish" (though technically it would be a "Frankenfish's monster," but that's neither here nor there) and worry it could get loose and destroy the wild Atlantic salmon population. AquaBounty assures opponents that all its salmon are bred female and sterile, making their survival in the wild impossible (which sounds ominously familiar). According to ABC, laws don't require stores to label the AquAdvantage, and it's likely consumers won't even know they're eating it. Whole Foods, Trader Joe's, Target, and others have already vowed not to sell the genetically altered salmon, the Post reports.