Environment and aquaculture in developing countries

Table 1. Marine cage salmonid production (in tonnes) in Canada, Norway, Scotland and Ireland (Source

of material, country reports containedin reports ofthe ICES Working Gmup onthe Environmental Impact

of Mariculture)

Country

Canada Norway Smtland Inland

Pacific Atlantic

Year (Salmonhmt) (Salmon) (Salrnodtmut) (Salmonltmut) (Salmodtmut)

and Pacific coasts) for example, production
increased byZ63% nnd283%,respectively,
during the period 1988 to 1991. In Norway
salmonid production has increased from
an annual production of 12,906 to 160,655
tonnes (representing an average increase
of 138% per year) during the period 1982
to 1991. This expansion, often without any
apparent control, has brought aquaculture
into conflict with other users of aquatic
resources, particularly with government
and nongovernmental organizations
promotingnature conservation. It isknown
that substantial amounts of waste are
produced from intensive fish farming. For
example, from Gowen andBradbury (1987)
it can be estimated that approximately 32
kg of soluble nitrogen and 300 kg of
particulate carbon waste are generated
per tonne of fish produced. The potential
for large amounts of waste to be generated
together with increased human activity
associated with fish farming has often
been cited as the reason why aquaculture
development is not in accord with the
requirements for coastal nature
conservation.
It is clear that in some cases the ways
in which the industry began and expanded,
have compounded environmental change

associated with intensive fish farming. In

some locations, ecological change has had

a negative effect on farm production and

forced the fish farmer to move to an

alternative site. In addition, the rapid

development of cage farming in sheltered

coastal waters has brought the industry

into conflict with other activities such as

tourism and recreation. In this paper some

ofthe environmental issues associated with

intensive fish farm development are

reviewed. Solutions are suggested which

may be of value in managing the

environmental impact associated with the

development of coastal aquaculture in

developing countries.

The Development and Expansion of

Intensive Cage Culture

During the initial development phase

of intensive fish farming in Norway and

Scotland, individual production units were

generally small, with an annual production

in the order of 50 to 100 tonnes.

Furthermore, at this time the primary

requirements for a site were: suffhient

water depth to accommodate cage netting;

shelter from potential storm damage,