Did you use cure #1 and salt to prepare the fish ?? If not, vac packed and shipped in a warm environment, 40-140 deg F, is ideal for botulism to grow and/or pathogens.... read the links on Fish / Salmon etc. in my signature line..... Dave
Any member reading this, please copy in your smoking fish section for future reference...
http://seafood.ucdavis.edu/haccp/compendium/chapt07.htm
Packaging conditions that reduce the amount of oxygen present in the package (e.g. vacuum packaging) extend the shelf life of product by inhibiting the growth of aerobic spoilage bacteria. The safety concern with these products is the increased potential for the formation of C. botulinum toxin before spoilage makes the product unacceptable to consumers.
Achieving the proper concentration of salt and or nitrite in the flesh of salted, smoked, and smoke-flavored fish is necessary to prevent the formation of toxin by
C. botulinum type E and nonproteolytic types B and F during storage and distribution. In salted fish, the salt concentration alone is responsible for this inhibition. In smoked and smoke-flavored fish, salt works along with smoke and any nitrites that are added to prevent toxin formation by
C. botulinum type E and nonproteolytic B and F (Note: nitrites may only be used in salmon, sable, shad, chubs, and tuna - 21CFR172.175 and 21 CFR 172.177).