Glándulas genitales

There are a number of different terms that describe the practice of managing aquatic organisms in rice-based farming systems. The most commonly used expression is probably “rice-fish culture”; in- deed, fish is the most important organism in the ricefield which is used for food. However, since there are more aquatic organisms to be found in the ricefield than just fish, a broader term is needed. On the other hand, “integrated agriculture-aquaculture farming systems”does not restrict itself to rice- based farming systems and may also encompass the integrated production of livestock and fish. It is too diffuse a denotation for the types of systems discussed here. Therefore, the term “small-scale aquaculture in rice-based farming systems” (or shorter: “rice-aquaculture”) was chosen from this point of the study onwards to define the management of all types of aquatic organisms in ricefields or in close association with ricefields (e.g., through on-farm water flows)15_{. This definition summarizes a}

multitude of systems which can be classified according to management intensity, growing period, field design, cultured species and stage in the production cycle (Figure 3.1)16_{. However, the first and}

foremost distinction that has to be made is between capture and culture systems. Capture systems are the most traditional form of utilizing aquatic organisms from ricefields. In these systems, wild fish and other aquatic organisms enter the flooded ricefields where they populate and reproduce. They

15 _{The term “rice-fish culture” will continue to be used if other authors are cited and in cases where it can be as-}

sumed that the discussion is restricted to the culture of fish in ricefields.

16 _{The culture of fish in deepwater rice areas will not be considered in this study due to its distinct production}

Intensive Extensive

Concurrent Rotational Pond

Trench Refuge Pond Refuge

Monoculture Polyculture

Carp Tilapia Others

Grow-out System Fingerling Production

are harvested at the end of the rice growing season. The only possible modifications in the fields are sumps which are dug in the lowest regions of a group of fields (Khoo and Tan 1980). Whereas culture systems have been developed mainly for fish, capture activities have encompassed all aquatic organ- isms in the ricefield that can be used for food (see section 3.1.2).

As the term implies, culture systems involve the deliberate modification of ricefields and their stocking with one or several species of fish or other aquatic organisms. The distinction between inten- sive and low-input culture systems refers to the use of external material inputs like feeds and fertiliz- ers; it does not describe labor input which can be quite high in an otherwise low-input system. Feeds can either be on-farm resources like rice bran, animal manure or household wastes, or additional inor- ganic fertilizer can be applied to stimulate primary production in the water (Edwards and Kaew- paitoon 1984; McClellan 1991). This latter option, however, raises production costs compared to the use of on-farm resources as fish feed.

In general, two types of growing periods can be distinguished: rotational, i.e. between rice har- vests and concurrent with the rice. The latter is often considered rice-cum-fish culture in the strict sense. However, fish may also be produced in ponds separated from the fields which nevertheless are connected to rice through on-farm water flows. Very elaborate three-tier systems have been devel- oped in which poultry is raised above a pigsty over a fish pond. The poultry manure is eaten by the pigs and whatever is left unutilized is washed down to the pond together with the pig manure, both as fish food and fertilizer (Delmendo 1980). The fertile water of the pond in turn irrigates the ricefield. In Indonesia, three types of growing systems can be found which are characterized by the sequence of rice and fish in the cropping cycle. According to Ardiwinata (1957), fish were first grown as a second- ary or fallow season crop (palawija). Later, when demand for fish grew, fish production was under- taken between rice crops (penyelang or intermediate cropping), mainly to produce seed fish for resale to pond owners. In addition, the concurrent cropping of rice and fish (minapadi) was initiated and ex- tended so that up to three fish cultivation periods (for seed fish production) could be accommodated in one rice crop (Koesoemadinata and Costa-Pierce 1992).

In concurrent and rotational rice-aquaculture, various modifications of the ricefield are possible. Farmers can raise the dikes of the field, dig a trench with a depth of about half a meter or excavate a pond refuge with a depth of about one meter in a low-lying part of the ricefield. These modifications serve the purpose of providing the fish with the necessary water depth even in times of water scar- city. As a rule of thumb, it is estimated that the pond refuge takes away 10% of the field area that could otherwise be planted with rice (dela Cruz 1990). In recent years, the trench refuge has not been recommended as it was found to be too risky with water levels falling below the depth required by fish (dela Cruz 1990).

The most commonly cultured fish species are carp, tilapia, silver barb (Puntius gonionotus) and snakeskin gourami (Trichogaster pectoralis) (Lightfoot et al. 1992a). Both mono– and polyculture of these species are practiced, but they are not evenly distributed across countries. While carps are pre- dominantly found in ricefields in Indonesia, India and China, tilapias occur in the Philippines, China and Thailand. The other two species are mainly cultured in Thailand (Lightfoot et al. 1992a).

A final distinction of production systems can be made with regard to their stage in the fish produc- tion cycle. Most rice-fish systems are growout operations, but the ricefields can also be used for nurs- ery operations (Lightfoot et al. 1992a). In Indonesia, raising fingerlings in ricefields was shown to be more profitable than growout (Costa-Pierce 1992; Purba 1997).