After years of resistance from advocacy groups as well as regulatory and pandemic-related delays, the first genetically engineered (i.e., GMO or bioengineered) salmon made its official debut in the American food supply last June. But the AquAdvantage Salmon hasn’t made much of a splash. In fact, it’s barely on the market, said Jaydee Hanson, policy director at the Center for Food Safety (CFS).

Still, AquaBounty, the company that raises the salmon, has big plans to expand. So, here are some quick answers to questions you might have about the futuristic fish.

What are the health and environmental concerns?

AquAdvantage Salmon is Atlantic salmon modified with DNA from Chinook salmon and the cold-tolerant ocean pout. AquAdvantage fish grow twice as fast as their non-GMO cousins in their early stages, which means they require less feed. The amount of feed that farmed fish consume has long been one of the biggest criticisms lobbed at the aquaculture industry, and AquaBounty markets the innovation as an environmental win. According to the U.S. Food and Drug Administration (FDA), the agency completed a “comprehensive analysis of the scientific evidence” and concluded that raising the salmon at approved farms would have no significant environmental impacts and that the fish are safe to eat.

But a coalition of organizations that includes CFS say the FDA’s assessment was insufficient; in a 2020 ruling, a California court agreed with them. Hanson says the main environmental concern is what might happen if the GMO fish escaped and bred with wild Atlantic salmon. In Norway, for example, genetic pollution from farmed fish has devastated wild salmon populations.

Currently, the FDA has only approved production of sterile GMO salmon in closed, land-based systems, minimizing that possibility. But Hanson said AquaBounty’s egg production facility is close to the shore on Prince Edward Island, so the risk of escape due to extreme weather events is still present. He also speculated that employees at the farms could take the eggs to raise fish in local waterways, and that the company may try to get ocean-based GMO salmon farms approved in the future: This April, Maine’s Department of Marine Resources rejected the company’s permit application for an offshore salmon farm due to concerns that it would use genetically modified eggs.

In an email, AquaBounty President and CEO Sylvia Wulf told Civil Eats the GMO salmon “will not be raised in ocean-based pens” and that the company’s land-based systems utilize multiple containment strategies so that “the risk of AquaBounty’s fish to the environment remains, and will continue to remain, low.”

In terms of health, Hanson and other advocates say that the research FDA reviewed to determine safety was far from adequate. The study that found no conclusive risks related to allergenicity included just six salmon in each research group. And the two small studies that evaluated whether the fish contain elevated levels of concerning growth hormones were based on what Michael Hansen, a senior scientist at Consumer Reports, calls “sloppy science and deficient data.” In one, for example, hormones were measured in fish that were just two ounces, not when they had reached the much larger size at which they’re sold.

Finally, many people eat salmon as a source of healthy omega-3 fatty acids. While farmed salmon including AquAdvantage salmon are a good source of those fats, because of their diets, farmed salmon tend to contain higher amounts of less-healthy omega-6s, tipping the ratio of omega-3s to omega-6s in the wrong direction. Hansen said the research so far suggests that AquaBounty’s genetic engineering alters that ratio even further.