>grain-fed salmon might not equal that of wild salmon.  Does anyone have a
>reliable source that displays the difference in fat composition of
>grain-fed vs. wild salmon?

This information is in the USDA nutrient database.
A good way to view this is via:
    http:/www.juggernaut.com.au/food/
    http://www.nal.usda.gov/fnic/cgi-bin/nut_search.pl

Search for "+salmon +raw" and then compare a few results.
Here's a highlight:

Finfish, salmon, Atlantic, wild, raw:
18:2 linoleic 0.172 g
18:3 linolenic 0.295 g

ratio: 0.58  (about 2 to 1 of o3, which is pretty good)

Finfish, salmon, Atlantic, farmed, raw:
18:2 linoleic 0.586 g
18:3 linolenic 0.094 g

ratio: 6.23 (about 6 to 1 of o6, which is pretty bad)

Of course, the USDA SR13 has no information about the "super salmon"
we've been discussing here, nor the herring-fed farmed salmon.

-Bruce
p.s. I will do a tryptophan search and post results. I can't do that
from here at work, so it'll probably be a day or two until I remember
to do it from home.