AquaBounty claims there are multiple barriers in place to prevent gene escape, including temperatures near the river’s mouth that are considered intolerably hot to Atlantic salmon. Also, the fish are screened to be all-female, and are sterilized, so that in the unlikely event of an escape the genes would have no way of spreading to the wild salmon population, the company has said.

The sterilization techniques are not 100 percent effective, however, which means that some fertile females could get through. This bug in the process was the basis for a $500,000 grant from the United States Department of Agriculture (USDA) last October to improve the company’s sterilization procedure. The grant was later cancelled after public outcry.

With regard to the idea that warm water near the river’s mouth would create a barrier to salmon escape, Kapuscinski finds the evidence that’s been presented thin scientifically. It’s true that dissolved oxygen levels in water go down as temperature goes up, and salmon are sensitive to dissolved oxygen, she said. But there are many variables, such as seasonal variation in water temperatures, and differences in salmon temperature tolerance created by genetic modification.

A key step in the approval process was the September 2010 meeting of the FDA’s Veterinary Medicine Advisory Committee (VMAC), which convened to discuss the human and environmental dangers posed by AquAdvantage salmon.

While the overall mood of the meeting was that the fish are probably safe for human consumption and not a threat to the environment (an idea many have challenged), several of the scientists there, including Kapuscinski, detailed their objections to the lack of rigor that had gone into the studies thus far. Problems with the studies included insufficient sample size data, sample sizes too small to be statistically significant, and absence of standard statistical methods that would be expected for such a precedent-setting decision. “We’re really worried that this sets the bar too low,” Kapuscinski told me.

At the VMAC meeting, Kapuscinski again addressed the assumption that warm water temperatures downstream from the Panamanian grow-out facility provided a barrier for escape. “The assessment suggests that water temperatures in the lower reaches of the Panamanian river and Pacific Ocean will be lethal to these transgenic fish but has their thermal tolerance been measured?” she asked. “Published research on coho salmon shows an increased thermal tolerance resulted after growth-transgenesis.”

In layman’s terms, research has shown that coho salmon genetically modified to grow faster are not as sensitive to changes in water temperature as wild type coho salmon. Such tests need to be done on the AquAdvantage salmon, she urged.

Her comments were cut short at the meeting due to time constraints, but she emailed me her full statement, which concluded: “Any failure of a multiple confinement system means that, once AquAdvantage salmon escape, the release cannot be undone because these fish are mobile organisms with very low but not zero likelihood of having some fertile escapees. We urge the FDA to require a transparent Environmental Impact Statement (EIS) that completes genetic and ecological risk assessment for the two proposed facilities and other commercial facilities likely to buy AquAdvantage Salmon eggs in the foreseeable future.”