2.3. Survey data collection
Data collection was carried out through two surveys: an initial
baseline survey for FMAS system characterisation, and a subsequent
one-year monitoring survey to estimate inputs and outputs of FMAS.
The same standardised methods were used throughout all study sites.
The surveys were designed and pre-tested by the project team, and all
interviews were carried by local teams of native speakers.
During the baseline survey (September to December 2001), thirty
households were surveyed per village. Information was collected on
type and surface area of FMAS, on management practices, and on the
presence of self-recruiting-species. To ensure adequate representation
of all the types of FMAS, stratified sampling was used in villages
where less than half of all households were considered to be engaged
in aquaculture (defined to farmers as ‘the activity of stocking hatchery
fish in their aquatic systems’). In such villages, 20 households were
selected at random from the village list and 10 were chosen at random
from a list of farmers engaged in aquaculture. If more than 50% of the
households practiced aquaculture, all households were chosen randomly
from the village list. Only the households selected at random
from the village list were included in analyses of system characteristics
and distribution. Households sampled specifically from the aquaculture
stratum were used only in the analysis of aquaculture practices.
The number of households selected at random represented between
10% and 40% of the total number of households in each village. A total of
529 households were surveyed during the baseline survey.
The monitoring survey was conducted in the same villages covered
in the baseline survey, over a period of 13 months from February 2002
to April 2003. Nine households per village were selected for monitoring,
from the sample of households covered on the baseline surveys.
Targeted selection was employed to identify households for the
monitoring survey to ensure representation of different system types,
household socio-economic status, and leadership structures. As far as
possible, the proportional distribution of FMAS types found in the
random sample was maintained. In Vietnam, households with ponds
were intentionally overrepresented in the sample, as most households
only had rice fields and a random sample would have provided
little information on households with other FMAS. This was accounted
for in subsequent analyses. Data on farming, fishing, consumption,
income and expenditure, and resource use were collected. Information
on fishing (species, size, number, catch and effort data) were collected
with a one-week recall. Visual aids such as sticks and bowls of
different sizes were used to aid recall (Garaway, 1999). All monetary
values were converted to US Dollars using average exchange rates
during the monitoring period (when 1 US$ was equivalent to 3990
Cambodian Riel, 42 Thai Baht, and 15,300 Vietnamese Dong).