Henk Stander
Aquaculture Division,
Department of Animal Sciences, University of Stellenbosch
T
he rapid growth of aquaculture over the last fifty
years has raised questions
concerning its environmental sustainability. Aquaculture is
among the fastest growing food
production sectors in the world and
this trend is set to continue. However, with increasing production
comes increasing environmental
impact. For aquaculture to remain
sustainable, this future growth
must be met in ways that do not
erode natural biodiversity or place
unacceptable demands on ecological services.
As human population increases and
industries grow, water becomes a
scarce resource that has many conflicting uses. The fact that traditional aquaculture production systems
usually require relatively large
amounts of water limits production
of fish in many regions. Environmentally, effluents from traditional
aquaculture systems, which are
characterized by high volume and
relatively low pollutant concentrations, are difficult to treat economi-
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cally with conventional wastewater
treatment technologies. Consequently, it seems to be inevitable
that aquaculture will have to face
more stringent restrictions over development in many areas of the
world, as concern over environmental impact and competition for resources growths. In fact, concern
over the impact of aquaculture
wastes and effluents has already
brought aquaculture under the
scrutiny of many regulatory agencies in many developed countries.
These limitations are a formidable
challenge to the development of
aquaculture. The concerns for water
conservation and the environmental
impacts of aquaculture activities
have promoted the development of
technologies for water reuse and
water quality conservation.
The Ocean and its Possibilities:
Norway is the world’s second largest farmed fish exporter, despite
the fact that it still farms only one
species at a time. The law prohibiting multi-trophic aquaculture dates
back to a time when there was a
lack of understanding about the
ecosystem, according to Anne Lise
Leonczek, leader of the innovation
project Ocean Forest. This Norwegian marine biologist at Bellona is
currently spearheading an effort to
see how the seafood industry can
utilize the naturally growing mussels and algae around salmon farms
to create a sustainable and environmentally friendly solution to fish
farming. Blue mussels would be
grown and utilized to filter water
and reduce salmon sea lice instead
of chemicals, while cultivated algae
would absorb CO2, produce fish
food and boost fish health. Research around the world shows that
integrated aquaculture production
has a huge potential. The concept
of producing several species in fish
farming, also known as Integrated
Multi-Trophic Aquaculture, is common practice in other countries.
Asia has become leaders in this kind
of applications. Chinese for example have a project in Sungo Bay,
east of the Shandong islands,
where they simultaneously culture
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