<<So even though farm-raised salmon are fed fish oil as a supplement, its
not
present in the final product?>>

  Sure.  According to the USDA Nutrient Database, raw farm-raised salmon
has:

20:5 n-3 = 0.618
22:6 n-3 = 1.293


  But remember, the omega-6 rich grains are not natural to fish, so with
farm-raised salmon you have omega-6's to offset.


<<Roughly how much lower is tuna than Salmon in EPA?>>

  Tuna, 100 grams, fresh, raw:

  20:5 n-3 = 0.283
  22:5 n-3 = 0.125
  22:6 n-3 = 0.890

  Salmon, 100 grams, fresh, raw:

  20:5 n-3 = 0.321
  22:5 n-3 = 0.287
  22:6 n-3 = 1.115

  Note that in the natural tuna and salmon that there is the 22:5 n-3 that
is missing in the farm-raised salmon.

<<Is canned salmon farm-raised?>>

  It can be.  Most salmon is now farm-raised.  I live on the coast.  The
only time our supermarkets have wild salmon is when salmon are running (late
June-early July).  The rest of the time it's all farmed.  Salmon is
available in some specialty stores year-round for $15-$22 a lb.

Siobhan