I really don't understand all this work and expense for seafood. I admit I have never done salmon, but shrimp, crawfish, catfish, red fish, snapper, grouper, ling, ever fish I've ever froze...... we cover it in water and freeze it. As a kid we froze in the waxed 1/2 gal milk cartons. Greatest seafood freezing container ever made, We're talking 20 to 30 years with no freezer burn and no texture change and none of that freezer taste. Now we use ziplocks. just insure that the pouch has zero air and you don't need a vac pump to get it out.
I know I am just a simple minded country boy but it seems a lot of trouble to par-freeze, warp, freeze, wrap..... Just put 'em in the Ziploc, leaving one corner of the zipper higher than the other squeeze till the water starts to come out and seal. No air, no freezer burn.
I have specks and strippers and reds been in the freezer for years and years still when thawed they come out exactly as they were put in.
Its the easiest preservation I can do. Seafood in the freezer and tomatoes in the canner.