10 Status and Future Perspectives in Aquaculture
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standing stocks have generated great losses to the shrimp industry, and appear to
still remain a problem (Graslund and Bengtsson 2001, Alonso-Rodriguez and PaezOsuna 2003, Avnimelech and Ritvo 2003, Fast and Leung 2003).
10.5.2 Cages and Rope Cultures
Cage fish farms and land based fish farms using flow through or recycling technologies
represent the high-technological solutions for fish cultivation. The majority of the
world’s cage fish farms are, however, still relatively primitive wooden cage systems
only suitable for protected locations. On the other hand, the most cost-efficient
production of fish today is undertaken in large cage farms situated in relatively open
and exposed locations. There are two main types of modern cage fish farms, one
system with cages suspended in a rigid framework of a steel construction and one
with flexible, wave resistant cage units made by plastic tubes, suspended and moored
independently to form an overall flexible main structure. The latter structure is
apparently becoming the most feasible solution.
Feeding and maintenance is highly mechanized and automated in the most modern
cage farms. The European production of salmon, sea bass and sea bream is mainly
undertaken in modern cage fish farms, and salmon farming has been the main driver
of these technological developments. The feed conversion efficiency (feed invested
per fish produced) was traditionally a potential main weak point of cage culture,
because of severe feed losses. Modern salmon farms are constructed and operated
in a way that this is no longer a problem, the feed conversion efficiency is normally
around 1 kg feed used per kg fish produced.
The long-line cultures represent cage culture like system that can be used for
benthic plants and animals, and these are primarily used for mussels and seaweeds. The
long-line structures used around the world are highly diverse, adapted to cover the
local requirement, species and production costs. Shallow waters have required special adaptations, for example for oyster farming. The structures carrying the oysters
are net systems suspended from the bottom to the surface. The technological state of
the systems for shellfish and seaweed cultivation is also highly variable, the most
advanced and industrialized technology used for shellfish appears to be that used
for production of green mussels in New Zealand.
10.5.3 Land-Based Farms
Intensive farming of fish in flow-through and recycling aquaculture systems (RAS)
has made major progress during the last decades, and there are now developed concepts which allow inland production of marine fish. In RAS, the water drained from
the production tanks is carefully and successively treated with biofilters, skimmers,
UV, ozone and other optional treatment methods to remove organic and inorganic
waste from the water before it is reused for aquaculture (Blancheton 2000). It will
still take some time before such systems are widely used, because they require
315
standing stocks have generated great losses to the shrimp industry, and appear to
still remain a problem (Graslund and Bengtsson 2001, Alonso-Rodriguez and PaezOsuna 2003, Avnimelech and Ritvo 2003, Fast and Leung 2003).
10.5.2 Cages and Rope Cultures
Cage fish farms and land based fish farms using flow through or recycling technologies
represent the high-technological solutions for fish cultivation. The majority of the
world’s cage fish farms are, however, still relatively primitive wooden cage systems
only suitable for protected locations. On the other hand, the most cost-efficient
production of fish today is undertaken in large cage farms situated in relatively open
and exposed locations. There are two main types of modern cage fish farms, one
system with cages suspended in a rigid framework of a steel construction and one
with flexible, wave resistant cage units made by plastic tubes, suspended and moored
independently to form an overall flexible main structure. The latter structure is
apparently becoming the most feasible solution.
Feeding and maintenance is highly mechanized and automated in the most modern
cage farms. The European production of salmon, sea bass and sea bream is mainly
undertaken in modern cage fish farms, and salmon farming has been the main driver
of these technological developments. The feed conversion efficiency (feed invested
per fish produced) was traditionally a potential main weak point of cage culture,
because of severe feed losses. Modern salmon farms are constructed and operated
in a way that this is no longer a problem, the feed conversion efficiency is normally
around 1 kg feed used per kg fish produced.
The long-line cultures represent cage culture like system that can be used for
benthic plants and animals, and these are primarily used for mussels and seaweeds. The
long-line structures used around the world are highly diverse, adapted to cover the
local requirement, species and production costs. Shallow waters have required special adaptations, for example for oyster farming. The structures carrying the oysters
are net systems suspended from the bottom to the surface. The technological state of
the systems for shellfish and seaweed cultivation is also highly variable, the most
advanced and industrialized technology used for shellfish appears to be that used
for production of green mussels in New Zealand.
10.5.3 Land-Based Farms
Intensive farming of fish in flow-through and recycling aquaculture systems (RAS)
has made major progress during the last decades, and there are now developed concepts which allow inland production of marine fish. In RAS, the water drained from
the production tanks is carefully and successively treated with biofilters, skimmers,
UV, ozone and other optional treatment methods to remove organic and inorganic
waste from the water before it is reused for aquaculture (Blancheton 2000). It will
still take some time before such systems are widely used, because they require