A while ago there was some traffic here concerning a recent paper in the
journal Science about high levels of environmental pollutants in farmed
salmon, but based only on what folks had read about the paper in the
popular press. The Pew Charitable Trusts has the paper itself at:
http://www.pewtrusts.com/pdf/salmon_study.pdf.

The Institute for Agriculture and Trade Policy in MN says that the FDA
only rarely tests for PCBs (levels 8 times higher in farmed than in
wild salmon, according to the study) or for dioxins (11 times higher).
http://www.iatp.org/iatp/iatpnews/img/0401.html

IATP also has an interesting press release and article on efforts by
some U.S. regulatory agencies and the aquaculture industry--in response
to growing resistance to large fish farms in coastal areas--to develop
large-scale aquaculture operations in the open ocean.
http://tinyurl.com/2oabd

JR