(ii) Fishing nets can have various mesh
sizes depending on the species being fished.
This controls the size of fish
caught and helps reduce the number of
accidently 'unwanted' and resulting 'discarded' fish.
A bigger mesh will allow smaller fish
to 'escape' and grow into breeding adults, hence helping to
maintain fish stocks.
In fish farms, the cages are placed in more sheltered
estuaries or bays to minimise the effect of rough water and
their natural food is often supplemented with other
fish-based protein products. There is a quite a lot of criticism of
ALL factory farming methods (see section (f) below) and the
following comments ....
Nearly half of all fish consumed
worldwide each year are raised in aquafarms. Farmed fish
spend their entire lives in cramped, sometimes dirty enclosures,
and many suffer from parasitic infections, diseases, and
debilitating injuries - which means chemicals and
antibiotics are used to help the fish survive.
Food is added to the enclosed nets to
feed the fish, who then produce large amounts of waste. The
waste can leak out causing eutrophication and death of wild
species - the waste contains pathogens. Fish farms are
breeding grounds for parasites, again these can escape and
threaten wild species.
Predators like seals and sea lions are
attracted this food resource, but can get trapped in the
nets and die.
The farmed fish can escape and compete
with indigenous species of fish.
Fish tank farms only contain one
species and are therefore low on biodiversity - they are
kept free of any plants or predators, the parasites and
microorganisms are usually killed.
For more see section on
reduction of biodiversity
The Food and Agriculture Organization of
the United Nations reports that the aquaculture industry
is growing three times faster than land-based animal
agriculture, and aquafarms will surely become even more
prevalent as our natural fisheries become exhausted, is
this good sustainability?
