A recent study showed that genetically modified salmon can produce hybrids with brown trout, a closely related species. The study also showed that the GM hybrids were even more dominant in the natural ecosystem than their GM parents.
Salmon and brown trout are similar species that can sometimes produce hybrids in the wild. These natural hybrids are similar to the non-hybrid fish in terms of feeding and predation. In other words, they don’t impact the activities of either the trout populations or the salmon populations.
However, when researchers crossed the GM salmon with a brown trout, they found the resulting GM hybrids grew even more rapidly than their GM parents. In a lab environment that recreated natural stream conditions, the GM hybrids grew so rapidly, both the GM salmon and the non-GM salmon and trout experienced stunted growth.
Advocates of genetically modified salmon point out two things in their defense. First, the GM salmon will be created sterile, with only a 5% error rate (meaning 5% of GM salmon will have full reproductive capabilities). Second, the salmon and brown trout hybrids in nature are sterile.
Both of those points are true, but consider the following scenario:
Supposing the GM salmon becomes the salmon farming industry’s favorite fish for stocking their pens. It is estimated that roughly 3 million farmed salmon escape each year and there’s no reason to believe that GM salmon won’t be able to escape just like their non-GM counterparts. (Yes, I know GM salmon are supposed to be raised in the Panamanian hills, but how long do you think that restriction would last once profits are involved?)
Out of 3 million GM salmon escapees, 5% would be able to reproduce, or about 150,000. Most of those would breed with other salmon, with effects we’ve already discussed on EDB. Some of them would breed with brown trout. Those GM hybrids would outcompete the other hatchlings in the river. According to the study referenced above, the GM hybrids suppress the growth of natural salmon by 54% and GM salmon by 82%.
In that scenario, the GM hybrids would die off at the end of the year, but they would have affected the growth of the native salmon significantly. Those remaining native salmon would be easier prey and would take longer to reach reproductive size. The GM salmon escapees would still be around and able to produce a few more GM hybrids in the coming years, which would continue to impact native salmon populations. The impact on wild fisheries would be significant. People would lose their livelihoods.
Trout photo via Shutterstock