Browsing by Subject "Integrierte Aquakultur"

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A case study: Fish production in the integrated farming system of the Black Thai in Yen Chau district (Son La province) in mountainous North-western Vietnam - current state and potential
(2009) Steinbronn, Silke; Becker, Klaus
Son La province is located in mountainous north-western Vietnam and belongs to the poorest regions of the country. In the valleys of this province, fish farming is one of the major activities among farmers who belong to the ethnic Black Thai minority. Up until now, the aquaculture system practiced here has not been scientifically investigated. There is generally very little data available regarding the aquaculture of resource-poor farmers in Southeast Asia. This lack of information can be partly explained by the difficulty in obtaining this data. However, a solid understanding of current aquaculture systems is necessary for any kind of future involvement. Within the course of a special research program (SFB 564), aquaculture practices in three communes of Yen Chau district (Son La province) were surveyed between 2004 and 2006. The research was conducted in a holistic way in order to obtain a detailed description of the typical local aquaculture system with its potentials and limitations. In addition, measures for improvement were developed, which will be tested during the next phase of the special research program. The data was collected and analyzed on three different levels. On the ?macro level?, general data is presented regarding the land use and irrigation system in the studied area. Data on the ?meso level? concerns the aquaculture and agriculture system and was predominantly collected through interviews with 155 farmers, 22 village headmen and other stakeholders. On the ?micro level?, an in-depth investigation based on measurements and close observation of 6 individually selected case study farms is presented. This data includes the limnological pond conditions, fish growth rates, food conversion and the profitability of the aquaculture system. The data gathered during these investigations compensates for the information that could not be satisfactorily gathered through the interviews alone. Currently, around 63% of the households in the study area produce fish in ponds. The aquaculture production is closely linked with other farming activities and is integrated into the overall irrigation system. Farmers stock different carp and tilapia in polyculture with the main species being grass carp. Fish are mainly fed leaves and by-products of crop production, weeds and manure, e.g. from buffalo. The pond system is feed-based and exhibits a more or less continuous water flow; both of these features are rather atypical for small-scale aquaculture. In the case study farms, the average fish stocking density was 1.0 fish m-2. Calculated based on one hectare, the average daily feed application was 37.1 kg dry matter (DM) and the annual net production of aquatic species 1.5 tons ha-1, of which roughly 2/3 were sold. The average conversion of feed (DM) to aquatic species biomass was 7.7:1, and the conversion of added nitrogen (feed and manure) to produced nitrogen (aquatic species) was 14.7%. The yields in the presented system are relatively low compared to other feed-based aquaculture systems. Nevertheless, it has been shown that aquaculture production contributes significantly to food security, generates income and plays a significant role in farmers? lives. At present, the local market in Yen Chau cannot be completely satisfied by the districts? fish production alone. Recently, a road was upgraded that connects the north-western mountains with the country?s capital Hanoi. As a result, fish from the more intensive aquaculture in the lowlands has started to flood the local markets. This development is expected to proceed, which will leave farmers unable to compete in the market in the future. In order to produce fish in a sustainable way, the current system must be improved so that the local fish production increases. There are various reasons that can explain the relatively low productivity in the ponds. These include an unclassifiable grass carp disease that leads to high mortalities, poor water quality, low fish growth rates caused by low quality of fish seed, low quality of feed and manure applied as well as low natural food availability in the ponds. Furthermore, farmers seem to have limited knowledge regarding basic aquaculture techniques, which may be explained by the lack of training or extension services available in this field. In the present study, a ?basket? of modification measures have been proposed. These measures concern the farms themselves (e.g. improved pond management), the institutional and political framework (e.g. support of the local hatcheries) as well as the research. The focus of the next part of the special research program will be the identification of the causative agent of the grass carp disease and the development of prevention and treatment strategies. Additionally, a modified watering and feeding management system will be tested scientifically. It is expected that this locally adapted, improved pond system will lead to significantly higher fish production.
Development of supplemental diets for carp in Vietnamese upland ponds based on locally available resources
(2010) Nguyen Ngoc, Tuan; Focken, Ulfert
Cyprinids play very important role in aquaculture, especially in Asia and Pacific regions. Vietnam is not an exception. Although aquaculture in Vietnam increased dramatically recently, its high value products such as catfish, tiger prawn seem to be unaffordable for the people in rural areas, especially for the mountainous ethnic minority in the North who are more independent to herbivorous and omnivorous fish such as grass carp, Indians carp, and common carp. Yen Chau is a district of Cyprinids play very important role in aquaculture, especially in Asia and Pacific regions. Vietnam is not an exception. Although aquaculture in Vietnam increased dramatically recently, its high value products such as catfish, tiger prawn seem to be unaffordable for the people in rural areas, especially for the Son La province, located in mountainous region in North-Western Vietnam. In this district, Black Thai ethnic minority accounts for approximately 54% population. Besides producing huge amount of grain and tuber crop such as maize and cassava for selling, aquaculture in a small poly-culture pond system is also a very typical activity which supplies an important nutritional source for human consumption and income generation as well. However, even though most of farmers in Yen Chau own at least one pond each, the demand on the local market cannot be covered (Steinbronn, 2009). Recently, unknown diseases causing high mortalities could be the reason of the decrease of grass carp production. To avoid risk from losing grass carp, farmers are tending to change the composition of the fish species stocked in favour of e.g. common carp and mud carp without having an appropriate feed base for these species. So far, no high quality feed was applied into the pond system. Therefore, the study entitled ?Development of supplemental diets for carp in Vietnamese upland ponds based on locally available resources? was conducted to not only contribute to an improvement of income and food security in the region but also meet the appeal of improvement of scientific knowledge on cyprinids which is inadequate with their great contribution. In the study, most of the possible feed ingredients were collected and analyzed for nutritive and non-nutritive values. Based on the results of the analysis a number of diets were formulated for 30% of CP and 10% of CL then tested by common carp. In total, four experiments were designed. The first was conducted in laboratory in which common carp were fed by local pelleted feed with 25, 50, and 75% protein derived from local ingredients. Results of this trial were confirmed by the trial 2 which was implemented under pond condition at Hanoi University of Agriculture. Trial 3 was conducted to compare different protein (full fat soybean meal and soybean cake) and carbohydrate sources (maize and cassava powder). Furthermore, sweet potato leaves were preliminarily investigated in fish feed inclusion. The last trial, trial 4, was carried out to evaluate the use of earthworm for common carp. Trial 1, 3 and 4 were designed for a recirculation system in which five common carp were stocked in each aquarium of 40 l with 3 replicates. Water flow through the aquaria was maintained at 6-7 litters per minute. Water temperature, DO and pH were kept at 25-27°C, above 4 mg/l and around 7.0-8.0, respectively. The photoperiod was set up at 12 hrs light:12 hrs dark. Fish were fed daily five times metabolic body mass requirement for eight weeks. The trial 2 consisted of four feeding groups (3 test diets and 1 control), each having three replicates. In each net, 45 common carp were stocked, Fish were fed three times per day (8h, 12h, and 16h) at a feeding rate of 5 times of maintenance requirement manually. Feed amount was adjusted every ten days after taking the weight of fish. The total trial lasted for 2 months. Analytical results show that all of local materials have good nutritive values, similar or better that those in other regions. Besides, fish meal and many other ingredients can be used as source of protein such as full fat soybean meal, soybean cake, meat meal, as well as earthworm powder. This earthworms Perionyx excavatus show a suitable quality for fish feed, high protein (71% of DM) and amino acids in comparison with many conventional protein sources, including fish meal. Replacement of 70% of protein (~ 20% of DM) by earthworms can significantly improve growth of fish. However, it is still unclear in full replacement fish meal by this material. Using maize and cassava in Yen Chau is also feasible because these materials not only are cheap but also are the most available. Among all plant materials, full fat soybean seems to be the best ingredient with high protein and lipid content. In contrast, fish seem to be deficient of nutrient by feeding sweet potato leaf inclusion diets. In conclusion, except for sweet potato, all of local ingredients can be used for fish feed formulation. The local feeds were well digested, utilized by omnivorous common carp. Despite local feed ingredients did not give the best growth of fish, they gave the best results in term of economic return. Local ingredient feed gave the lowest cost of feed as well as the lowest cost of fresh fish produced. The field trial fish performance seems to be better than in the laboratory due to receiving certain amount of natural food. Thus, fish utilize feed more efficiently resulted in reduction of feed conversion ratio as well as cost of feed per unit of fish produced. Transfer knowledge about low-cost feed to the local farmer together with basal techniques of producing, storing, and effective using fish feed is an important issue which could help farmers to improve production of fish in the region as well as contribute to poverty alleviation in the rural areas in Vietnam.