Aquaculture – An Ecologically Efficient Food Production
Increasing world population and increasing wealth pr. capita
places a high demand for quantity and quality of food. The
culture of seaweed, shellfish and fish is in a unique position to
fill an important part of this demand in an economically and
ecologically efficient manner.
Based on the UN median population scenario and on an
extrapolation of the existing trend for fish consumption up to 40
kg/Cap/yr., DHI estimates the scenario outlined in figure (1):
Fig. 1 Scenario for world
aquaculture production
The total demand is calculated from population and consumption
per capita. The aquaculture production is the total demand minus
the capture fisheries supply. As shown in fig. 1 capture
fisheries are expected to decline for two reasons: it will not be
economically competitive in relation to modern highly efficient
aquaculture production methods and secondly, capture fisheries
are in general very stressful to the natural environment in the
sea, and needs gradually to be downsized to an ecologically
acceptable level.
The accuracy of such scenario calculations is inherently low.
However, it seems safe to forecast an aquaculture production
level of between 200 and 400 million tons / yr. in year 2100.
The species, which DHI see as major contributors to this growth,
are seaweed, mussels, penaied shrimp, salmonoids and different
types of vegetarian whitefish. We are aware that many
aquaculturists dream about introducing new and wonderful very
expensive species, which can be sold in huge quantities. However,
this is but a dream. The terrestrial animal production is
completely dominated by a few easily domesticated species:
cattle, pigs, chicken and sheep(1). And
there is no reason to believe that the case will be different for
fish production. The emphasis and interest on new species divert
valuable resources away from solving much more important problems
for the industry like disease, feeding, culture technology and
environment.
From a technological point of view DHI forecasts two main
methods:
-
Land-based farming of small quickly growing organisms with high
stocking densities using recirculation to conserve energy,
water and material.
-
Offshore mariculture facilities growing big fish in huge net
cages under hydrographically optimal conditions.
Ultimately one could imagine, that all animal production could
eventually take place in animal cell cultures producing
infinitely long fish filets in fish vats(2).
Aquaculture is unfortunately seen by some parties as being a
particularly high impact food production industry. This is
definitely not true. If aquaculture is well managed and located
correctly, it is more ecological efficient than traditional food
production methods. Surely, all food production methods impact on
nature and environment by using land and water and by discharging
nutrients and auxiliary substances. Aquaculture has many
advantages though. Fish can be grown in the sea not needing to
use valuable land resources. Mariculture of seaweed, shellfish
and fish use saltwater, which is in endless supply, for its
growth. Since fish are cold-blooded animals they need less energy
than their competitors on land, and can be grown with less food
and with smaller discharges of nutrients.
Modern fish production, for example salmons, relies on other fish
for its feeding. However the amount of fish meal and fish oil in
the feed is gradually declining and will eventually be
substituted by plant produced proteins and fatty acids, as the
capture fisheries have no chance of supplying the rapidly
increasing aquaculture production on its own.
By substituting some of the terrestrial food production with
aquatic food production, it is possible to acquire a greater
total ecological efficiency.
It takes thorough planning of location, solid production
equipment and very good management using the best practices to
arrive at this point. By doing this a steady decoupling of the
value of the production from the impact on nature and environment
can be accomplished.
DHI is involved in all these issues and has developed tools for
the planning and management of aquaculture. DHI is particularly
strong using 2D and 3D models for detailed impact assessments.
Furthermore, we have developed methods for biomonitoring of
seafarm impacts using Ulva lactusa. We can make water forecasts
for the fish farmer of all relevant hydrographic variables
including oxygen and toxic algae. Just now we are developing a
virtual fish farm concept, aimed towards a detailed 3D of water,
water quality and fish behaviors in the farm. In the sidebar are
given some examples. Below is shown the National Danish
Mariculture Plan outlining the blue areas, which are highly
suitable for production of rainbow trout as well economically as
ecologically.
The great potential for aquaculture is dawning to interested
parties all over the world. DHI is an important player in this
field and has defined aquaculture as a strategic R/D area for the
institute. In this capacity we will allocate resources to
increase the knowledge and develop new tools for the planning and
management. We would like to be in dialogue with the industry,
authorities and NGOs and will implement user participation in the
R/D planning.
DHI Aquaculture Activities
-
The development of eel ( Anguilla anguilla) culture in
recirculated systems for Danish Shell
-
Development of a mussel growth model for the Danish Ministry
of Food
-
Implementation of treatment methods for shrimp farming in
Thailand for Danida
-
Development of the Danish National Sea Farm Plan for the
Danish Ministry of Food
-
EIA for Musholm Lax, the biggest Danish sea cage fish farm
with a capacity of 3.000 tons trout
-
The water forecast system for the Sea of Chiloe for Intesal,
Chile
-
The relative impacts of auxiliary substances on Danish
streams for the Danish Aquaculture Association
-
Over wintering of trout in the Danish Sea for the Danish
Aquaculture Association
-
Water quality criteria for fresh water pond discharges to
rivers for the Danish Aquaculture Association
-
The use of seaweed and mussels for uptake of nutrients
discharged from fish farms. DHI R/D project.
-
Toxic algae forecast systems for fish farmers for the
European Space Agency
-
Training programme for the Malaysian Sabah State Aquaculture
Department in the development of 30,000H of aquaculture
reserves
-
EIA of a 1,200 port development in Kampot, Cambodia, situated
only 2 km from one the largest seaward farms in the world
-
Development potential for Cambodian coastal aquaculture
-
EIA court case of the suitability of a farm site in the
Marlborough Sounds, South Island of New Zealand
-
Fishery Resource Impact Assessment (FRIA) for a 3000H mussel
farm development in Tasman Bay, NZ
For further information, please contact Karl Iver Dahl-Madsen (kdm@dhigroup.com) & Neil
Hartstein (ndh@dhigroup.com)
1) Guns, Germs & Steel. Jared
Diamond.
2) A Meaty Question. The Economist. Sept. 21,
2006
