|
Global aquaculture production has grown at 11
percent a year over the past decade and is
projected to continue increasing. Along with this
growth, there has been a trend within most
developing and many developed countries toward the
increased use of artificially compounded feeds
(aquafeeds) for farmed finfish and crustaceans.
This trend has been particularly apparent in
developing countries with the progressive
intensification of farming systems. In the main
Low-Income Food-Deficit Countries compounded feeds
are increasingly being used for the production of
both lower-value staple food fish species (mainly
freshwater finfish such as carp, tilapia, and
catfish) and higher-value cash crop species for
luxury or niche markets (mainly marine and
diadromous species such as shrimp, salmon, trout,
yellowtail, seabass, seabream, and grouper). In
fact, the production of aquafeeds has been widely
recognized as one of the fastest expanding
agricultural industries in the world, with growth
rates in excess of 30 percent per year.
Asia is by far the leading region in aquaculture
production where the bulk of Asian finfish and
crustacean aquaculture is obtained in
semi-intensive pond farming systems. The great
majority of these farming systems, particularly for
freshwater non-carnivorous finfish production
(which accounts for over 80 percent of the total
finfish production in Asia), depend on the use of
natural foods through proper pond fertilization
using inorganic and organic fertilizers,
supplemented with prepared feeds.
Generally speaking, pond fertilization is
important to increase the availability of natural
foods for fish and crustaceans. The pond water can
be fertilized with purchased inorganic fertilizers,
or locally available organic fertilizers may be
used, e.g. compost made with plant and animal
wastes, animal manure, or plant material
The prepared feeds range from single feeds
available on-farm such as grass or rice bran to
farm-made formulated feeds and commercial feeds.
This includes aquatic and terrestrial plants
(duckweeds, azolla, water hyacinth etc.), aquatic
animals (snails, clams etc.) and terrestrial-based
live feeds (silkworm larvae, maggots etc.), plant
processing (de-oiled cakes and meals, beans, grains
and brans) and animal-processing by-products (blood
and feather meal, bone meal etc.). Formulated
commercial feeds are composed of several
ingredients in various proportions complementing
each other to form a nutritionally complete
diet.
If the aquaculture growth potential is to be
realized and maintained, then considerable
quantities of nutrient inputs in the form of
fertilizers, supplementary feeds or complete
compound aquafeeds will have to be available on a
sustainable basis. In this context, establishing
good aquafeed manufacturing practices is important
for aquafeed producers. National surveys and
documentation concerning feed and fertilizer
resources and their availability and use could be
very helpful for fish farmers
Aquafeed development faces two major global
challenges
1) The need for finfish and crustacean
farming systems to develop feeding strategies based
wherever possible upon the use of non-food grade
locally available feed resources
Aquaculture needs to further increase its net
contribution to total world fish supplies. At
present, nearly all farming operations for
carnivorous diadromous finfish, marine finfish and
crustaceans - based on the use of aquafeeds - are
net fishery resource `reducers' rather than
`producers'. The quantity of inputs of dietary
fishery resources in the form of fishmeal, fish
oil, crustacean by-product meals, `trash fish',
etc. exceeds outputs in terms of farmed fishery
products by a factor of two to three. Long-term
efforts must be placed on the use of by-products
from the large agricultural production sector,
including terrestrial animal by-product meals
resulting from the processing (i.e. rendering) of
non-food grade livestock by-products; plant oilseed
and grain legume meals; cereal by-product meals;
and miscellaneous protein sources such as
single-cell proteins, leaf protein concentrates,
invertebrate meals, etc.
2) Improved feed formulation and on-farm feed
and water management strategies tailored to the
needs of the farming system or farm production
unit
As farming systems intensify, either in terms of
increased stocking density and consequent nutrient
input or in terms of number of farms per unit area,
the need to develop environmentally cleaner or
'greener' feeding strategies becomes greater. The
net results of excess nutrient loss are an economic
loss to the farmer with a potential deterioration
of the aquatic environment within and possibly
outside the farm, subsequently increasing stress on
the cultured animals and increased susceptibility
to disease. Thus, feeding regimes should be
designed to minimize nutrient loss and faecal
output, and to maximize nutrient retention and the
health status of the cultured species. Such actions
would in turn help to improve the social acceptance
of and confidence in the sector in terms of aquatic
resource use and environmental sustainability. In
this respect, feed manufacturers have the very
important responsibility of ensuring that the feed
they provide to farmers is both nutritionally
correct for the intended farming production system
and is managed correctly by the farmer.
|
