Greetings Miss Frankie,
The main difference is that you will have to test, according to sampling plan, for benzo-a-pyrene, a by-product produced during the smoking process. Also, unless they already have it, you should acquire the MSDS/ CoA etc for the pellets(?) or whatever it is that you use for producing the smoke.
Request proper documentation from your supplier that the salmon is free from anisakis and other appropriate health records or medical treatment they used in the batch. This is a bit important to have in your archives cause concumers don't tend to apply heat treatment to smoked products and if something has survived, then you are in for a bad ride (smoking as a 'kill step' is debatable). Also, regular pathogen checks (Listeria has the potential to survive smoking process).
Also, if they can't provide you with a histamine analysis, you should include that too on your analyses plan (set at specific time intervals or if you notice something off during reception or raw product (like slight discoloration or lower temperature of the transport means etc).
Lastly, keep in mind the possibility for anaerobic thioreducing clostridia. Smoking process and vacuum are good conditions for them.
Regards!