The Food and Drug Administration said Friday that it had concluded that the fish 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 FDA’s draft environmental assessment, posted on its website, will be open to public comment for 60 days, it now seems highly likely that the salmon will be approved. An agency spokesman said it was not possible to predict when such a decision might be made.

The assessment was dated May 4. It was unclear why it took until now for it to be released, but backers of bringing the salmon to market believe it was because the Obama administration was afraid of an unfavorable consumer reaction before the election in November. Some environmental and consumer groups quickly condemned the FDA assessment Friday.

“The GE salmon has no socially redeeming value,” said Andrew Kimbrell, executive director of the Center for Food Safety, a Washington advocacy group opposed to farm biotechnology. “It’s bad for the consumer, bad for the salmon industry and bad for the environment. FDA’s decision is premature and misguided.”

The AquaAdvantage salmon, as it is called, is an Atlantic salmon that contains an extra growth hormone gene from the Chinook salmon and a genetic switch from the ocean pout, an eel-like creature. The switch keeps the growth-hormone gene constantly on, allowing the salmon to reach market weight in about 18 months instead of three years, the company has said.

The FDA tentatively concluded in 2010 that the salmon would be safe to eat and safe for the environment under the conditions that AquaBounty proposed to produce it.

The FDA said that there would be multiple biological and physical measures taken to keep the salmon from escaping the fish farms. Even if they did escape, the agency said, they could probably not survive and mate in order to establish themselves in the wild.

The FDA also said that if it did not approve the salmon, attempts might be made to get approval from other countries, perhaps with less restrictive containment conditions so that adverse environmental events would be more likely to occur.