Wild versus Farmed Salmon

[Guest guest]

[Among farmed salmon, Chilean salmon shows the lowest contamination,

while ish salmon shows the highest. Even Chilean farmed salmon,

though, should not be eaten more often than once every two months(!).

Wild chum salmon seems to be the safest, according to this report.]

Dec. 22, 2005

Stick to wild salmon unless heart disease is a risk factor,

risk/benefit analysis of farmed and wild fish shows

By S. Lang

On the one hand, farmed salmon has more heart-healthy omega-3 fatty

acids than wild salmon. On the other hand, it also tends to have much

higher levels of chemical contaminants that are known to cause

cancer, memory impairment and neurobehavioral changes in children.

What's a consumer to do?

In general, a new study shows that the net benefits of eating wild

Pacific salmon outweigh those of eating farmed Atlantic salmon, when

the risks of chemical contaminants are considered, although there are

important regional differences.

Those are the conclusions of Barbara Knuth, Cornell professor of

natural resources who specializes in risk management associated with

chemical contaminants in fish, and Schwager, Cornell associate

professor of biological statistics and computational biology and an

expert in sampling design and statistical analysis of comparative

data. The two have co-authored a benefit-risk analysis of eating

farmed versus wild salmon in the Journal of Nutrition (November, Vol.

135).

" None of us [study authors] argues that the benefits of salmon are

not real. But the dirty little secret is that there are risks, " said

Schwager, noting that even taking into account the risks, the

benefits of salmon may be particularly worthwhile for some groups.

" For a middle-aged guy who has had a coronary and doesn't want to

have another one, the risks from pollutants are minor ones, and the

omega-3 benefits him in a way that far outstrips the relatively minor

risks of the pollutants, " he said. " But for people who are young --

and they're at risk of lifetime accumulation of pollutants that are

carcinogenic -- or pregnant women -- with the risks of birth defects

and IQ diminution and other kinds of damage to the fetus -- those

risks are great enough that they outweigh the benefits. "

Knuth added: " Because we found regional differences in contaminants

in farmed salmon, with Chilean salmon showing the lowest levels and

European (particularly ish) farmed salmon showing the highest

levels, careful consumers with a history of heart disease could

choose farmed salmon from Chile for their high omega-3 content and

relatively lower level of contaminants. " She noted that farmed salmon

from North America would be a better second choice than European

farmed salmon.

The researchers' benefit-risk analysis showed that consumers should

not eat farmed fish from Scotland, Norway and eastern Canada more

than three times a year; farmed fish from Maine, western Canada and

Washington state no more than three to six times a year; and farmed

fish from Chile no more than about six times a year. Wild chum salmon

can be consumed safely as often as once a week, pink salmon, Sockeye

and Coho about twice a month and Chinook just under once a month.

In a study published last spring (Environmental Health Perspectives,

May 2005), the research team reported that the levels of chlorinated

pesticides, dioxins, PCBs and other contaminants are up to 10 times

greater in farm-raised salmon than in wild Pacific salmon, and that

salmon farmed in Europe are more contaminated than salmon from South

and North American farms.

The team also published a study this fall (Environmental Science and

Technology, Vol. 39:8622) that found that farmed salmon, on average,

contain roughly two to three times more beneficial fatty acids than

wild salmon, presumably because of the differences in the diet on

which the fish are raised.

" Our results also support the need for policy and regulatory efforts

to limit pollution of our waters and clean up pollution that has

occurred, and thus ultimately reduce the risk side of this equation

by reducing the potential for human exposure to these contaminants, "

said Knuth, adding that the country of origin of fish sold should be

clearly labeled so consumers can make informed decisions