lowlands, which were (and are) more economically developed than the mountainous region, began to flood the local markets. This development can be expected to
continue, and it is likely farmers will be unable to compete in this market in the
future. In order to produce fish in a sustainable way, the current system must be
improved so that local fish production levels can be increased.
Vietnam is a very dynamic country in terms of its level of agricultural development, but its inhabitants will need to adapt quickly and flexibly in order to deal with
frequently changing markets. Currently, aquaculture is only a minor component in
the local farming system, but its importance might increase with greater farm
specialization and market orientation, and it has been widely recognized that
encouraging the further development of aquaculture production can contribute in
a sustainable manner to food security and poverty alleviation in developing
countries (Tacon 1997; Edwards 2000; Prein and Ahmed 2000).
8.3 Current and Potential Feed Resources for the Local
Aquaculture System
One of the factors mentioned in Sect. 8.2 as contributing to the low level of fish
production in these ponds is the limited feed base, both for the grass carp and for the
non-grass carp species. The current and potential feed resources for these species
are discussed below, with the data presented based on interviews with local
stakeholders and on an in-depth investigation into individual ponds during the
period 2003–2006 in Yen Chau district (Steinbronn 2009).
The feed types currently used in the research area consist mainly of plants, either
terrestrial or aquatic, collected from the wild or of the leftovers from cultivated
crops. The typical feed types used are shown in Table 8.2. Important plant-derived
inputs to ponds include cassava leaves, chopped cassava tubers, cassava peelings
and fermentation residues. From banana plants, the leaves and young or soft parts of
older (pseudo-) stems are also used, as are the leaves from maize and bamboo plants
and occasionally from mulberry and vegetables. Additional inputs include the byproducts of rice cultivation, such as rice bran and broken rice, as well as weeds and
aquatic plants. The weed from paddy fields most commonly used for fish feed is
barnyard grass (Echinochloa crusgalli). Animal-derived pond inputs include
manure from large ruminants or pigs, of which buffalo dung is by far the most
important.
Quantitatively the most important feed inputs (on a dry matter (DM) basis) used
during the study period were fresh cassava, banana and maize leaves, weeds
collected from the paddy fields and buffalo manure.
Most of the above feed types cannot be consumed directly by humans; however,
through their application in the ponds, they can be converted into high-value animal
protein. Grass carp is believed to be the major species that feeds on the applied
green fodder, accounting on average for 80 % of the applied feed material used
8 Improved Sustainable Aquaculture Systems for Small-Scale Farmers . . .
289
continue, and it is likely farmers will be unable to compete in this market in the
future. In order to produce fish in a sustainable way, the current system must be
improved so that local fish production levels can be increased.
Vietnam is a very dynamic country in terms of its level of agricultural development, but its inhabitants will need to adapt quickly and flexibly in order to deal with
frequently changing markets. Currently, aquaculture is only a minor component in
the local farming system, but its importance might increase with greater farm
specialization and market orientation, and it has been widely recognized that
encouraging the further development of aquaculture production can contribute in
a sustainable manner to food security and poverty alleviation in developing
countries (Tacon 1997; Edwards 2000; Prein and Ahmed 2000).
8.3 Current and Potential Feed Resources for the Local
Aquaculture System
One of the factors mentioned in Sect. 8.2 as contributing to the low level of fish
production in these ponds is the limited feed base, both for the grass carp and for the
non-grass carp species. The current and potential feed resources for these species
are discussed below, with the data presented based on interviews with local
stakeholders and on an in-depth investigation into individual ponds during the
period 2003–2006 in Yen Chau district (Steinbronn 2009).
The feed types currently used in the research area consist mainly of plants, either
terrestrial or aquatic, collected from the wild or of the leftovers from cultivated
crops. The typical feed types used are shown in Table 8.2. Important plant-derived
inputs to ponds include cassava leaves, chopped cassava tubers, cassava peelings
and fermentation residues. From banana plants, the leaves and young or soft parts of
older (pseudo-) stems are also used, as are the leaves from maize and bamboo plants
and occasionally from mulberry and vegetables. Additional inputs include the byproducts of rice cultivation, such as rice bran and broken rice, as well as weeds and
aquatic plants. The weed from paddy fields most commonly used for fish feed is
barnyard grass (Echinochloa crusgalli). Animal-derived pond inputs include
manure from large ruminants or pigs, of which buffalo dung is by far the most
important.
Quantitatively the most important feed inputs (on a dry matter (DM) basis) used
during the study period were fresh cassava, banana and maize leaves, weeds
collected from the paddy fields and buffalo manure.
Most of the above feed types cannot be consumed directly by humans; however,
through their application in the ponds, they can be converted into high-value animal
protein. Grass carp is believed to be the major species that feeds on the applied
green fodder, accounting on average for 80 % of the applied feed material used
8 Improved Sustainable Aquaculture Systems for Small-Scale Farmers . . .
289