Canada has approved sale of genetically modified salmon.

I find it entirely plausible that eating these salmon is safe. The concern for these salmon is that some might escape and transmit the modified genes to wild salmon. Just one escaper might cause permanent and irreparable harm.

Supposedly the modified salmon are sterilized, but how reliable is that process? 99%? 99.9%? There are systems to prevent the salmon from escaping, but how reliable are they? 99.9%?

Is that reliability maintained when thousands of low-paid workers have to run those systems, under management that doesn't want to immediately fix everything that breaks? The US has no Federal Salmon Agency to make sure every salmon farm gets an annual inspection and certify the people who maintain it.

If just one modified salmon in a thousand is not sterile, and just one in a thousand escapes, and the modified salmon number millions over the course of years, escapes of fertile modified salmon are almost a certainty.