Here is some recent news:

Farm-raised salmon, which is the kind commonly sold in grocery stores,
contain significantly more cancer-causing chemicals than salmon that are caught in
the wild, warn researchers from the University at Albany in New York, who
tested 700 salmon worldwide

Although the U.S. Food and Drug Administration insists the levels of 13
pollutants found in salmon are too low for serious concern, this new international
study shows that farm-raised salmon have enough dioxins and other potentially
cancer-causing pollutants that the researchers are cautioning consumers to eat
salmon no more than once a month. The Associated Press reports that the
average dioxin level in farmed-raised salmon was as 11 times higher than that in
wild salmon--1.88 parts per billion compared with 0.17 ppb. For PCBs, the
average was 36.6 ppb in farm-raised salmon and 4.75 in wild salmon

Answers to the big questions:
Where is most of the salmon farmed that we eat in the United States? Chile.
And that's good news. The pollutant level in Chilean salmon was not too much
higher than that found in some wild-caught salmon, notes AP.
Where are these contaminants coming from? The feed, which is made of fish oil
and meal from just a few species of ocean fish. This concentrates the ocean
contaminants to which the farm-raised salmon are exposed. Wild salmon eat a
greater variety. When any fish or animal absorbs these pollutants, they are
stored as fat and not secreted. So if the fish has the contaminates in its fat and
the fish is eaten by a human, the contaminants that were in the fish are then
stored in the human's fat. However, the salmon farming industry points out
that all the pollutant levels are well within the FDA's legal limits, notes AP.

Will the farmers change the feed? Many salmon farmers in the United States,
Canada, and Chile doing just that. But it's a slow process. Instead of using
fish oil in the salmon feed, they are switching to soybean oil and canal oil,
which don't have the pollutants.
What level of pollutants is considered safe? The government does not have one
set level of dioxins and PCBs that is considered safe in foods.
What can you do as a consumer? Until the farmers change the feed they use,
your best bet is to buy wild salmon. Wild salmon sells for about $15 a pound,
compared with $4 to $5 a pound charged for farm-raised salmon.
Will cooking help remove pollutants? If you do eat farm-raised salmon, the
FDA recommends cutting off the skin and grilling it. This will remove a
significant amount of PCBs, dioxins, and other pollutants stored in the fish fat.



One a similar note, we have ground buffalo available in a local market, I
called the company and they said that it is grain finished.  Do you think it is
still better than grain finished cow meat? Or just as bad?

Alex