I'll be preparing salmon baked on rock salt for 10 and am wonder how much salmon to purchase. Any advice?
I recommend between 6-8 ounces per person for an entree, 2-3 ounces per for a plated appetizer. 6 ounces works out to about 0.4 lbs, so you can do the math easily when you go shopping.
Make sure all of your guests like salmon. I've been invited to dinner twice with salmon being served, and it's one of the few things I can't even force myself to eat.
3 pounds should be sufficient as I assume you'll also be serving sides?? Yum!
I always plan on 6 ounces of fish per serving for a main course. I would probably buy 4 pounds, because should an extra guest materialize, you could wangle an extra serving .
I'd also get 4 or maybe even 5 pounds, depending, of course, on how much else you're serving. When it comes to salmon, I always try to have leftovers and all-too-seldom actually get them.
I'd err towards 5 lbs. - accounts for any unusable bits of a whole fish, plus I prefer having a bit too much than too little - I find it makes serving a 'communal' fish a little more relaxed. (With a filet pre-cut into individual portions, or salmon steaks, I'll be more precise and figure 6-8 oz/person.) Also, as Greenstuff said, leftover salmon is a great reward the next day.