My doctor told me years ago that Sockeye Salmon is non-GMO (and recommended Costco's offerings). A quick Search on Brave browser brought up this result from its AI Leo:
As of now, there is no genetically modified (GM) sockeye salmon available on the market. The only genetically modified salmon that has been approved for human consumption is the AquAdvantage salmon, which is a genetically engineered Atlantic salmon developed by AquaBounty Technologies.
And here's a piece of good news, especially for Canadians, where labeling as GMO of salmon was not required.