A recently published collection of 23 peer-reviewed and independent studies found evidence that some salmon from hatcheries are harming wild salmon populations as they compete for food and habitat. According to a release, five billion juvenile salmon are released from hatcheries worldwide. In some instances, these salmon are putting pressure on wild salmon and contributing to population decline (not to mention contributing to cases of sea lice).
In one case, chum salmon, a type of Pacific salmon, were released from Asian hatcheries and contributed to the decline of the wild chum salmon population in remote western Alaska, about 2500 miles away from where the hatchery-raised chum salmon was released.
"Genetic data show that these fish share the same feeding grounds in the open waters of the Bering Sea and North Pacific Ocean," says Greg Ruggerone of Natural Resources Consultants. "With billions of hatchery chum released each year, the abundance of adult chum salmon from hatcheries is now much greater than wild chum salmon, so it is not all that surprising that we are seeing evidence of competition in the North Pacific."
Another study in the Prince William Sound in Alaska touched on hatchery-wild salmon hybrids that formed as a result of salmon that strayed from the hatcheries. Implications of these hybrids include harming the "productivity, genetic diversity and fitness of wild salmon in this region." This is not the first study to discover that many salmon in the wild are not actually wild salmon. Similar results were found in the rivers around Kamchatka.
The release of hatchery salmon can also affect breeding opportunities for wild salmon, one study found.
While several of these studies suggest further investigations to figure out exactly how much wild salmon populations are harmed, the studies provide mounting evidence that the area is ripe for research. Check out all the studies here.
CORRECTION: An earlier version of this post referred to hatchery salmon as farmed salmon. We regret the error.