Interesting.....I usually defrost my bait night/day before a fishing trip in the fridge for a good few hours and just keep it cool at most. Any soft mushy bait just gets some cotton and maybe a bit of squid or something tough to hold it on the hook. Soft squishy salmon would give off its own mini berley trail so I would be happy to use it.

Otherwise a chilly bin and some ice might do it.