Opponents of genetically modified salmon, as well as consumer activists and environmentalists, told a US Food and Drug Administration advisory panel that it would be irresponsible not to require labels on the fish if it is approved for humans to eat.
The public has the right to know what it is consuming, the speakers said.
The advisory panel heard from opponents and supporters of the fish - including the developer of the fish, Massachusetts-based AquaBounty Technologies -- as it held two days of hearings that concluded to review the science of the fish that grows twice as fast as conventional salmon, and to hear public comment on whether the fish should be labeled.
Current federal guidelines would not require the fish to be labeled if the FDA determines the animal has the same material makeup as conventional salmon, the Associated Press reported.
AquaBounty says that genetically modified salmon has the same flavour, texture, colour and odour as conventional fish.
Only GM soybeans and corn for sale now
The FDA has yet to decide if the fish can be sold to consumers or whether it should be labeled, and it could be months before the agency does so, the AP said.
If the FDA approves the fish, it would mark the first time a genetically modified animal has been approved for dinner plates and restaurant menus. Currently, genetically modified soybeans and corn are being sold for people to eat.
AquaBounty believes that, if approved, the fish could help reduce pollution, disease and other problems associated with saltwater fish farms, as well as provide an alternative source of seafood to help reduce the impact of overfishing.
But opponents of approval, including many consumer advocates, worry that the fish would pose a threat to both the health of consumers and the environment.
On Sept. 3, a scientific panel of experts that advises the FDA paved the way for the approval of the genetically modified salmon, calling it "as safe as food from conventional Atlantic salmon."
The FDA's Veterinary Medicine Advisory Committee went on to say that the fish contained the same amount of nutrients and had "no biologically relevant differences" from ordinary farmed Atlantic salmon.
That's what worries consumer advocates, who say approving the salmon is opening the door to all sorts of genetically engineered animals, such as pigs and other mammals.
Research kept confidential
The FDA is regulating genetically engineered animals as it would a new veterinary drug, which means that much of the research and information about the product is being kept confidential, said Wenonah Hauter, executive director of Food & Water Watch in Washington, DC.
"We don't know if it's safe for humans to eat and the only research that has been done was done by the company," according to Hauter. "The FDA is an under-resourced agency that has had so much trouble with the regulatory system for foods - we've had tainted eggs, poisonous peanuts and other contaminations - and is now taking on something in a very non-transparent way."
Recently, Food & Water Watch was joined by 30 other animal welfare, consumer, environmental and fisheries groups, including the Sierra Club, which issued a statement citing concerns that the fish could escape and pose an environmental threat. Previously, another group of consumer advocates and others warned that "transgenic fish" could introduce new or unknown allergens into the food supply.
AquaBounty creates its salmon by taking a growth gene from the Chinook salmon and a gene "promoter" from the ocean pout, another type of fish, said John Buchanan, AquaBounty's director of research and development.
The pout gene promoter simply turns on the Chinook salmon growth gene, and is not actually "expressed" [active] in the modified fish. The resulting salmon grow to market weight about twice as fast as ordinary Atlantic salmon, though they don't get larger overall.
While it typically takes about three years for salmon to grow to market weight, AquaBounty's salmon get there in about 18 months, Buchanan said.
To safeguard the environment, Buchanan said the eggs will be treated so that all fish that grow from them will be sterile females. That means they will not be able to reproduce, nor will they come into contact with males to reproduce with, said Buchanan, whose firm would sell the treated eggs.
While farm-raised salmon are typically grown in ocean-based tanks, the genetically modified fish would be grown in land-based tanks, also minimising the chances of escape, he said.
"We have done a tremendous amount of work geared toward regulatory approval to show that the fish is healthy and safe," Buchanan said.
Genetically modified animals have been produced since the 1970s, according to background information in the FDA's briefing materials, but none has been approved for human consumption.
AquaBounty said bringing the salmon to market would take at least 18 months after approval. Farmers who want to grow the fish would also need FDA approval of their facilities.