Aqua Bounty Technologies

5 Myths About Transgenic Salmon

MYTH 1: Transgenic salmon grow much larger than other salmon -- so much so that they could gain a mating advantage or outcompete native salmon for food or space.

FACT: We have been working with our rapidly growing AquAdvantage™ Atlantic salmon for over 10 years now, and we have no evidence to suggest that these fish grow any larger than standard salmon. However, we do know that they reach market size faster.

FACT: There is no evidence that any farmed salmon compete successfully with wild salmon if they escape. In the West Coast, attempts to create “native” populations of Atlantic salmon in the Pacific by releasing millions of young Atlantic salmon in the 1940s all resulted in failure: the Atlantics all disappeared within a year or two following release. In the North Atlantic, two years after a major escape of 130,000 farm-raised salmon in Maine, only 6 found their way back to spawn. AquAdvantage™ salmon may be even less competitive because they lack the critical swimming speed to pursue prey, deplete their energy reserves more quickly and expose themselves to predators more often in the search for food.

MYTH 2: If transgenic salmon do breed successfully with native fish, their novel gene will escape into the wild gene pool and destroy native salmon populations, the so-called “Trojan Gene” theory.

FACT: The U.S. Food and Drug Administration will not approve the use of transgenic salmon in areas where they could escape into the wild unless they can be shown to be sterile. Aqua Bounty Farms has stated that in such areas it will market only sterile, all female transgenic salmon. This will ensure that there can be no gene flow to the wild salmon population, because sterile fish cannot reproduce.

FACT: Muir and Howard, the Purdue scientists who proposed the “Trojan Gene Hypothesis,” state that destruction of wild fish would occur only if escaped male transgenics were larger during the mating period than the non-transgenic wild males, and if their offspring were poor survivors. As we know, AquAdvantage™ salmon are not larger at sexual maturity, invalidating the key proposition in the hypothesis. Moreover, Muir and Howard did not study transgenic salmon. They designed a mathematical model based on the behavior of Japanese medaka, a small, freshwater fish that matures in 56 days and breeds daily until it dies. Salmon take three, five and even ten years to mature and most breed only once in their lifetime. Finally, of course, AquAdvantage™ salmon, when sterile and all-female, do not breed at all.

FACT: Male salmon do not necessarily gain a mating advantage because of size. In fact, “precocious parr,” only 6 inches in length, father about one-fifth of each new generation before they go to sea. Studies of escaped farmed salmon, which are almost always larger than wild fish, have found the mating success of the farmed salmon to be only 3% that of the native salmon.

MYTH 3: Sterilization is not 100 percent effective so we can’t be sure that transgenic salmon will really be sterile.

FACT: Triploidy produces 100 percent sterilization in female salmon because it prevents the development of the ovaries needed to produce eggs. The only uncertainties about the technique have been raised in the context of male salmon, grass carp and oysters. There is no scientific debate over the complete sterility of triploid female salmon.

FACT: Scientists can test for triploidy by scanning blood or embryonic tissues in a flow cytometer. The sterility of every batch of transgenic salmon eggs can be verified before they ever leave the hatchery.

MYTH 4: Transgenic salmon are voracious predators that will consume all the available food in an ecosystem and will prey on native juveniles.

FACT: AquAdvantage™ salmon may be prone to starvation in the natural environment as they learn to identify and hunt for wild food. They maintain a higher metabolic level for a longer period of time in food deprivation studies, and deplete their energy reserves more quickly than do standard salmon.

FACT: Any food competition would only occur in the marine environment because sterile transgenic salmon cannot produce the juveniles that occupy freshwater habitat. In the marine life stages, transgenic salmon would compete with older native salmon of about the same size. Because food availability is not limiting in the marine environment, transgenic salmon would gain no advantage from their higher feeding motivation.

FACT: Sterile female salmon do not engage in spawning behaviors and almost never return to freshwater habitat after they begin to feed at sea. Native juveniles are confined to freshwater habitat. Any predation risk would, therefore, be lower than now occurs in conventional salmon aquaculture. There is no evidence of predation by current farm escapees on native juveniles.

MYTH 5: Transgenic salmon produce antifreeze proteins and excessive amounts of growth hormone.

FACT: Our rapidly-growing Atlantic salmon produce no antifreeze proteins. Only the molecular “switch” from the antifreeze gene is used.

FACT: Our AquAdvantage™ rapidly-growing Atlantics produce similar amounts of salmon growth hormone as wild-type salmon, but they produce it through the entire year.