> The culprit [i.e., causing contamination] appears to be the salmon feed,
which contains higher
> concentrations of fish oil - extracted from sardines, anchovies and other
> ground-up fish - than wild salmon normally consume. Man-made contaminants,
> PCBs and dioxins make their way into the ocean and are absorbed by marine
> life.

Right.  So its better to buy wild salmon oil.  I buy a brand made
exclusively of wild sockeye salmon from BC.  The company describes:
"Sockeye salmon feed mostly on vegetarian food sources plus krill and
plankton which produces the beneficial carotenoid, astoxanthin, as is
indicated by the rich orange colour of the oil.  Wild salmon oil has a
naturally occurring 1 to 1 ratio of EPA to DHA."

This company mentions that their testing reveals mercury levels as
"negligible" (meaning below a very low level).

Rob