Developers of the fast-growing genetically engineered salmon first started the approval process with the United States (US) Food and Drug Administration (FDA) in 1995. In 2019, we are a bit closer to having the option of buying this fish for ourselves, as the FDA clears the final regulatory hurdle to allow sale of AquAdvantage salmon.
How were fast-growing GMO salmon created?
Canadian researchers created the fast-growing genetically engineered salmon with a growth hormone gene from Chinook salmon and a gene promoter from ocean pout. They microinjected the transgene into fertilized eggs of wild Atlantic salmon, and characterized the insertion.
The resulting genetically engineered fish are ~99.99986% Atlantic salmon, with the addition of just 4,205 base pairs in a genome of2.97 billion bases. Further, the growth hormone proteins from Chinook and Atlantic salmon are 95% identical. This leaves the ocean pout promoter as the only “new” element. The developers chose this promoter because genes it controls are continually expressing – always on – as opposed to the salmon promoter for growth hormone, which is only on in certain environmental conditions.
Even though the inserted growth hormone gene is always on, it doesn’t have much of an effect unless the fish have access to food. When allowed to eat as much as they want (fed to satiation), juvenile AquAdvantage salmon can grow nearly 3 times longer than conventional juvenile Atlantic salmon. But in a simulated natural environment with limited food, juvenile AquAdvantage salmon grew only a little larger than juvenile conventional salmon.
While AquAdvantage salmon grow faster, they do not grow larger overall – adult AquAdvantage salmon and adult conventional Atlantic salmon are the same size. The genetically engineered fish just get to that size faster and with less feed. As FDA describes, “the overall total amount of feed required to produce the same fish biomass was reduced by 25%” for AquAdvantage salmon. Read the article.