Micro level (measurement-based survey): Potentials and limitations in

By collecting data on the micro level, data that was not accessible through interviews alone could supplement the findings. Estimating reliable fish yields and growth rates in ponds, for example, is difficult - if not impossible - with interviews alone. Fish are regularly transferred from one pond to another, with different sizes stocked from different sources at different times and are frequently harvested for household consumption. Altogether, this leads to constantly changing stocking densities, which makes it extremely difficult for farmers to estimate current fish amounts. In addition, farmers usually do not take notes about their pond farming activities; thus, they are often not able to remember the stocked or harvested amounts. Upon inquiring about fish yields, farmers frequently refer to yields of grass carp only, since the grass carp tend to be the most important species for marketing, and neglect the yields of all other fish species. In particular, the production of tilapia and common carp is often not mentioned at all, probably due to the fact that these fish species are self-recruiting within farmers’ ponds so it is practically impossible to estimate their amounts.

Even though the data collection on the micro level provided quite reliable data with the use of record books and measurements for the selected ponds, a number of difficulties arose, which derived from the cooperation with the farmers as well as from the measurements themselves. The goal of the present study is to describe the aquaculture system and to reveal potential ways of improving the system. Therefore, the activities of farmers were only observed and any kind of interference was avoided as much as possible. Since interference was discouraged, requests to the farmer to alter normal aquaculture practices and time management could not be made; it was therefore impossible to select farms that fulfil the selection criteria defined and that all stock and harvest fish at around the same time. For the different rearing and cooperation periods, all of the data had to be converted in order to correspond with a hectare and year for better comparability. Therefore, farms are compared on the basis of varying initial fish weights, pond sizes, rearing periods, etc. These variables contribute to the different pond productivities found in the case study ponds.

Differences between the productivity can also be attributed to other factors such as the amount and composition of the feed applied to the pond as well as the types of water sources. High variations in pond productivities are very common in aquaculture research and the underlying causes often remain obscure (Edwards et al., 1996a). Edwards et al. (1996a) state that there might also be factors such as variations in silt content in the water as well as iron and aluminium content of sediments, which all might influence productivity.

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Differences in the pond productivities may further be related to the behaviours of the individual farmers as well as their social status. In the case study farms, the younger farmers, spent less time on their ponds due to heavier workloads in the fields. This is only partly represented in the daily labour input (Tables 20-22), which mainly refers to the time spent “effectively” for pond-related purposes (e.g. feed collection and application). Elderly farmers (e.g. the relatively old farmer of CK2), who usually do not participate in the physically demanding field work, spent much more time at the pond site “looking after the fish” in contrast to the relatively young farmers (e.g. the farmer of SV2). Better supervision of the pond may also be linked to the location of the pond; a pond near the house is comparatively easy to observe as compared to ponds situated far away.

The productivity, as expressed in the net fish production, deviated 71% between the lowest (1.12 tons ha-1 _year-1_{) and the highest (1.92 tons ha}-1 _year-1_{) yields among the case}

study ponds. Although the difference between the individual ponds may be considered high, especially when taking account the value of fish in relation to farmers’ incomes, the difference does not play an important role when comparing aquaculture systems with each other. The annual net production of 1 to 2 tons per hectare is generally low when compared with the yields reported from other feed-based systems. Therefore, despite the differences among the ponds, the data shows definite uniformity.

On-farm studies have to fit into the farmers’ normal schedule of activities. Scheduling important procedures such as stocking or harvesting, was often difficult. Arranged dates were frequently not maintained. Pre-fixed harvest dates, for example, had to be frequently postponed when either no new water was available or draining was not possible due to certain activities in the adjacent fields or ponds. It was also the case that farmers stocked or harvested a portion of their fish prior to the arrival of the researchers. This was the case when farmers had access to juvenile fish on short-term notice or when they harvested big fish due to apace cash requirements or social events, such as funerals, religious ceremonies etc. In the case of SV2, for example, farmers planned to harvest fish at a much later point in time, but they urgently required money for their house construction so they prematurely harvested a portion of their fish. Also, the sudden death of a household member of SV3 required the supply of food for the mourners. In these cases, the data (fish weights and amounts) was provided by the farmers. Since farmers have been provided with scales, they were able to weigh the fish and they usually immediately recorded the fish weights (with the exception of certain farms that were not considered on the micro level). The data from the farmers’ notes seemed to be quite reliable.

7 Discussion ₁₂₉

Since interference was kept as low as possible, the harvest of fish for household consumption was not suppressed. The stocking of different size classes and frequent removal of fish made it difficult to estimate the growth rates of the individual fish in the ponds as has been described in chapter 6.4.2. For determining the real growth rates, the conditions need to be more controlled and farmers’ behaviours should be aligned with the requirements of the researchers.

The maintenance of the farmers’ record books was performed correctly most of the time during the study period. However, they were neglected or poorly managed in times of very high labour peaks, such as during rice harvesting. Also, social challenges partly hindered farmers’ abilities to maintain the notes. This was the case with SV2, for example, when a household member was in hospital for a week. During these days, the cooperation partner was unable to update the book.

Even though farmers were trained and visited regularly, it probably occurred that feed amounts were only estimated or some minor inputs were neglected. For example, the application of fermentation residues from the distillation of liquor was frequently added to the ponds. Since the amounts were low and not considered to be important by the farmers, it occurred that farmers “forgot” to include those inputs. Also, certain inputs were not weighed but estimated instead. This occurred, for example, when farmers collected animal droppings from a nearby road and just put them into the pond. Although the notes in the farmers’ books may only give rough estimates of the real amounts, they are probably much more reliable than data gathered through interviews alone, especially when assessing the average amounts of feed year round and not only during the season of the interviews.

Compared with terrestrial animals, it is extremely difficult to gain an accurate overview of aquatic animals, since they are not easily visible and countable; this makes aquaculture research especially difficult. For example, it occurred that fish were lost in the case of farm VL3, which has neither been realized by the farmer nor by the researchers. The occurrence of uncertainties such as theft or floods made the evaluation of the data from VL3 impossible. Also, in the case of SV2, due to theft occurrence, not all data could be evaluated.

Although not all data could be gathered satisfactorily on the micro level due to the “uncontrolled” conditions, the data provided from these observations supplements the data gathered from the interviews. The case study ponds are representative of the interviewed farmers’ ponds since all ponds are managed in a similar way. Also, certain figures including the average amounts of fish sold or consumed within the household were quite similar in both surveys. The use of measured data and the records kept by cooperating farmers in connection

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with the long-term observation of the case study farms and their neighbours in addition to the data collected from the interviews with farmers and other resource persons led to the creation of a database that is able to describe the aquaculture system in a holistic way.