Do you know what specification you are buying and how much unnecessary work your Chefs may be doing to rectify a poor specification?
My advice when buying salmon fillets would be:
Compare
Make sure you are comparing like for like
A-Trim
If you specify A-Trim make sure you account for yield loss and time spent in additional prep for your Chefs
C-Trim
Try to specify C-Trim
Superior grade
Ask for superior grade (not ordinary)
Weight
Ensure you are charged fillet weight not whole fish weight and check the weight when it comes in