My thoughts would be to go with what the labels say, ie eat a portion size based on the label for that particular can. FYI, I have found this same type of difference in soy milk here in Australia - there are some large differences.
Just for fun I looked up [b:5591d6c7c4]pink salmon [/b:5591d6c7c4]( it does make a differnece) on Food standards australia,and found these results:
SALMON, PINK, CANNED IN BRINE 19.4
SALMON, PINK, CANNED IN BRINE, DRAINED 21.9
SALMON, PINK, CANNED IN WATER, NO ADDED SALT 19.4
SALMON, PINK, CANNED IN WATER, NO ADDED SALT, DRAINED 21.9
(red salmon is slightly higher about 22)
SALMON, RED, CANNED IN WATER, NO ADDED SALT, DRAINED 21.9
On the other hand I just had a thought: was wondering if you read the protein gms for [b:5591d6c7c4]serving size [/b:5591d6c7c4]and not per 100gms? In this case you would get a range 14-17 gms protein depending on serving size that ranged from 75-85gms per serve.
And... sorry i cant answer your question about a US based web site Hopefully someone else will ( I've lost my link)
It may help you to make up your mind ( if price is not the deciding factor) that I read somewhere that the wild salmon could be better for you as the farmed salmon are hand fed stuff that they may not necessarily find "in the wild". But then some say that the mercury content of the "in the wild" salmon can be higher - or is it the other way round? Whoops, perhaps someone will enlighten me here.
hope that helps