If I'm doing salmon fillets then I'll normally do 50c for 25 minutes, but a whole salmon is a different kettle of fish. I've done sous vide whole salmon on several occasions and I do 55c for 3 hours which works fine but dries out the fish a little more than I'd like.  I'm not really comfortable cooking anything at a temperature lower than 55c for long periods of time but I'd like a less dry whole salmon.  Does anyone else have any views / science on this one? Could I get away with doing a whole salmon at a lower temperature? 
Your temperature is inevitably going to dry the salmon out - it's too high.   As to whether it's possible to sous-vide whole salmon, I'm about to find out. But experience with smaller fish suggests the time goes up but the results can be very good.   There are some web resources which help calculate cooking times as size increases.  I suggest you try lower temperatures on smaller pieces to find what you like.   If it's 50C - which tastes dry to me - cook at 50C  I cook at 43C but that's about as low as I'd go. 