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FROM Norway to Canada, farmed Atlantic salmon are escaping in such large numbers that they are a threat to the local salmon. This could be prevented by making the farmed fish sterile. But there is a catch: the sterile fish are less nutritious.
Salmon farming has satisfied soaring demand without the need to catch ever more wild salmon. But it has also created an entirely new threat.
Farmed salmon have been transformed into a domesticated animal by selective breeding. They eat …