Integrated aquaculture in the highland region of Vinh Phuc Province, Northern Vietnam

• Research Institute for Aquaculture No. 1, Vietnam
• Flinders University, Australia
• Urrbrae Agricultural High School, Australia

The Ministry of Fisheries, Vietnam has placed integrated and sustainable aquaculture production in the highland region as the highest priority in its national research and development strategy. Aquaculture is a relatively new enterprise in the region and the aim is to integrate it with agriculture and livestock farming ('VAC' farming systems-consisting of garden, fish pond and livestock).
The VAC integrated farming system had already significantly boosted income levels of farmers in lowland areas. Studies carried out near Ba Vi in north Vietnam clearly indicated that the physio-chemical conditions faced by the farmers in the highland area were different from those of the lowland areas. But extension and development officers working in this area mainly had to rely on related work carried out elsewhere, which often did not provide adequate answers to the real problems the farmers face.
In order to develop an integrated farming system in the highland region in general and Vinh Phuc Province specifically some fundamental technical issues needed to be addressed. Adaptive research that investigated the successful recycling of nutrients in the highland area, while addressing the specific prevailing physio-chemical conditions, would help identify factors for sustainable development of primary production.

The overall objective of the project was to enhance integrated aquaculture production of small landholders in the highlands, using the VAC farming system. It addressed issues of pond productivity by fertilization with organic manure and recommended suitable fish species (including the composition, ratios and stocking densities to complement other farming activities in the VAC system).

Considering the complexity of pond dynamics a scale-up (microcosm to macrocosm) research and development approach was selected for undertaking this project. This also optimised resource usage and provided flexibility in undertaking experiments. The first study was a microcosm experiment using small aquaria, assessing the effects of many factors such as manure types and nutrient concentrations.
Based on these results, mesocosm experiments were carried out in small outdoor tanks to assess the effects of a reduced number of factors in conditions more closely representing farming situations. In the next stage, the experiments were conducted in ponds. These macrocosm experiments were carried out in real farm conditions and concentrated on fewer factors compared to the mesocosm experiments. While microcosm experiments conducted in aquaria mainly focused on nutrient and water interactions, mesocosm experiments looked at nutrient, water and fish interactions. The macrocosm experiments looked at the species interaction in the real farm situation.

Experiments compared organic and inorganic fertiliser applications along with a treatment termed grass carp polyculture (25% grass carp along with other filter feeding species + organic fertiliser). Key findings were that all three treatments were economically viable, provided the techniques were correctly followed. Thus a farmer could consider one or more options depending on his/her circumstances and resources available. The results will be the basis of guidelines for the mixed usage of organic and inorganic fertilisers in freshwater pond fish polyculture.

The grass carp polyculture resulted in maximum net production of 5.6 tonnes/hectare compared to 4.4 tonnes/hectare and 3 tonnes/hectare in the organic fertiliser and in inorganic fertiliser treatments respectively. The cost of production was highest in grass carp polyculture, followed by organic and inorganic fertiliser treatments. The organic and inorganic fertiliser treatments produced similar levels of net profit while that of the grass carp polyculture was comparatively higher.

The final trial in the farmer's ponds, where experimental technology was applied, achieved a high degree of success. The excellent performance of researcher-managed farms clearly demonstrated suitability of the technology.

Findings from the Vietnam component of the project were highly relevant to Australian research and development programs on integrated wastewater treatment and aquaculture production. A project in South Australia, jointly conducted by SARDI, Aquatic Sciences, Urrbrae Agricultural High School and Environmental Health Department of Flinders University, provided a link between the outcomes of the Vietnam project and their application in Australia. The Australian project objective was to develop models under local conditions for recycling farm waste through aquaculture.

Vietnamese findings were useful in the design of experiments and interpretation of results in the Australian wastewater treatment project. The highlights of the Australian study were a pilot-scale integrated wastewater treatment and an aquaculture model developed for Urrbrae Agricultural High School.

Further to the Urrbrae project a pilot trial was undertaken to grow carp in treated sewage water in Adelaide. Again the sewage treatment was adjusted to give nutrient levels suitable for fish culture. This trial was highly successful and the carp grew at a rate of 8 g/day, which was quite high compared to other semi-intensive aquaculture operations in South Australia. A commercial operation is likely.