The problem with freezing salmon is that the fat will still oxidize in the freezer. This is why most high quality frozen salmon is vac-pac'd (no oxygen=no oxidation). If you vac pac'd it then you should be good. It will be good for 3 months, un-vac pac'd, but not great..
I caught a 9 1/2 pounder last fall and ate it for 6
months; it was still O.K. (not great) in March. I
dried it out as much as possible before freezing.