Fish farming...

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2 total messages Started by gamma-hydroxybutyrate Wed, 26 Apr 2006 23:21

#31

Author: gamma-hydroxybutyrate
Date: Wed, 26 Apr 2006 23:21

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I was watching some PBS show called "Farming the Seas" which discusses
the relatively recent fish farming industry.  While the oceans are
already being overfished to the point of collapse, fish farming is
actually making the problem worse.

The major problems were escape of non-native fish into the surrounding
environment, disease from the farms infecting wild populations, and
then the part I'm interested in is that farmed fish require essential
fatty and amino acids from other fish, so that it might take up to
several times by weight in wild-caught fish to feed farmed fish.

So the farmed fish don't increase the fish supply, they deplete it much
like cows eating corn and soybeans deplete the usable energy content of
the plant material.  We get 100 tons of farmed salmon out of 300 tons
of anchovies or whatever other species.  And then the toxins in the
wild-caught feeder fish build up in the farmed fish so that they wind
full of contaminants from mercury to dioxin to PCBs.

My question is if there is any way to produce the essential feed
nutrients synthetically.  There should be a huge market for it, as
humans already pay top dollar for omega-3 fish oil supplements which
are rumored to contain high levels of mercury.  Figure out how to
synthesize it and related compounds economically and it would solve
the problem - we would be able to produce unlimited supplies of
toxin-free farmed fish.

Re: Fish farming...

#32

Author: Silvert
Date: Fri, 28 Apr 2006 07:46

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Keep in mind that the wild fish that are used to produce feed are
species that are not consumed for human food and are often from remote
locations that usually suffer less contamination than local fish. For
example, salmon grown in America and Europe may consume feed based on
Peruvian anchoveta.

And yes, there is lots of research on using plant-based feeds and other
approaches that are environmentally friendly.

There is a lot of alarmist literature out there which greatly
exaggerates the problems associated with fish farming. Comparing the
environmental impacts of aquaculture with those associated with other
forms of food production, such as feed lots and erosion and pesticides,
and considering the amount of effort that is going into solving these
problems, it is hard to see what all the fuss is about.

Bill Silvert
Habitat Ecologist

gamma-hydroxybutyrate wrote:
> So the farmed fish don't increase the fish supply, they deplete it much
> like cows eating corn and soybeans deplete the usable energy content of
> the plant material.  We get 100 tons of farmed salmon out of 300 tons
> of anchovies or whatever other species.  And then the toxins in the
> wild-caught feeder fish build up in the farmed fish so that they wind
> full of contaminants from mercury to dioxin to PCBs.

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