Environmental Engineering Reference
In-Depth Information
enough energy to reproduce. Human predation has exceeded the sustain-
able yield—the amount of fi sh that can be removed from the sea without
harming the species.
As we have done with meat from land animals, so also have we done
with fl esh from fi sh. We have added endocrine-disrupting chemicals to
the diet of both freshwater and marine fi sh that live near coastal sewage
outlets. The amount of estrogen coming out of swine and cattle is esti-
mated to be more than ten times higher than the amount the human
population puts out.
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Scientists at the National Institutes of Health
have found that male fi sh in contaminated rivers have been feminized
to the extent that only 20 to 30 percent of them are able to release fi sh
sperm. Those that do produce sperm produce up to 50 percent less than
do normal male fi sh. Also, the ability of the sperm to produce viable
offspring is reduced.
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Marine fi sh have suffered the same effects. In the Pacifi c Ocean near
Los Angeles, nearly 1 billion tons of treated and fi ltered sewage are
released into the ocean every day. Thirteen percent of fi sh caught near
the sewage pipelines had ovary tissue in their testes. Two related studies
found that two-thirds of male fi sh near one of the pipelines had egg-
producing qualities.
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No one knows whether eating the amounts of
pollutants found in the fi sh will cause reproductive problems in humans.
Other chemicals found in marine fi sh include antidepressants, fl ame-
retardant chemicals, and PCBs. Many artifi cial chemical products such
as prescription medications fl ushed down the toilet pass through sewage
plants and are ingested by marine life when the effl uent is piped into the
sea.
The catch of wild fi sh has stagnated at about 100 million tons since
1990, but the production of farmed fi sh has skyrocketed, from about 15
million tons in 1990 to 60 million tons in 2007. China produces more
than two-thirds of the world's farmed fi sh, with other East Asian coun-
tries producing most of the rest. The growth in aquaculture far outpaces
that in all other animal food sectors. In many fi sh aquaculture farms the
number of fi sh raised in limited areas can lead to parasitic and other
infections. Antibiotics are added to the fi sh food to combat this, as is
done with farmed cattle. The potential problem this creates is that the
drug will be ineffective when given to humans who become ill.
In addition, just as factory-raised cattle are different from pastured,
grass-fed cattle, factory-farmed fi sh are an entirely different source of
protein than wild fi sh. For example, farmed salmon contain much lower
amounts of healthy omega-3 fatty acids.
