It has been argued recently on this list that consumption of fish should be
kept to a minimum due to risk of mercury contamination.  The following
excerpt from Michael A Schmidt's "Smart Fats" suggests that this might be
an unnecessary precaution:

"Another interesting cultural point is raised when we look at Inuit mothers
from Norther Quebec, Canada.  Their diets are typically very high in seal
blubber and other foods rich in omega-3 fatty acids.  Unfortunately, the
foods in their region are typically contaminated with organochlorine
pesticides and PCBs.  In fact, their breast milk contains four to seven
times more of these toxins than non-Inuit mothers.  Doctors expected to
find brain degeneration and developmental delays in the children, but this
has not been the case.  This discovery has led doctors to suggest that
omega-3 fatty acids may, at least partially, help protect the brain against
toxic chemicals.(1)"

(1) Anonymous.  Organochlorines lace Inuit breast milk.  Sci News 1994;Feb
12;111

Best, Peter