Open Access
Review

Table 1

Characterization of the cumulative changes brought about by the three innovations described through the four principles of ecological intensification selected at the scale of the fish farming system by (Aubin et al., 2017).

Innovation 1: The production of ‘large’ tilapia in ponds with little or no feed Innovation 2: Heterotis and tilapia polyculture Innovation 3: Flooded rice
1 – Minimizing dependence on external resources Fish farmers produce tilapia weighing 250 to 400 g without the need for additional feed. Previously the tilapia produced did not exceed 50–100 g. The farming of the new species (Heterotis niloticus) does not call for any additional inputs. It is trophically complementary.
The natural reproduction of Heterotis in ponds produces a few hundred fry or juveniles which are exchanged within the fish farmers’ networks. Its double breathing facilitates its transport.
Rice production (1.9 to 3.5 tha−1) is higher than in the surrounding lowlands without specific inputs (0.8 to 1.2 t.ha−1). The fertility of the uncultivated plot is ‘saved’.
2 – Increasing the performance of aquaculture farming systems and product quality Tilapia weighing more than 300 g is well appreciated by the consumer (more flesh/biomass) and preferred to imported fish. It is very much in demand. The producer has 30% more fish to sell, with only a little additional labour. Sold at the same price as tilapia, Heterotis is considered a ‘good fish’ once its supra-gill organs are removed. Rice cultivation does not reduce fish production. The water restrictions after transplanting and harvesting are compensated for by the better maintenance of the pond.
3 – Improving the robustness, flexibility and resilience of systems through the integration of functional complementarity The risk of poor sales is low because it is a consumer product.
Fish farming fits in well with other activities and requires only a little extra labour. The fish load is adapted to the gradient of productivity of little or no feed pond environments (from 0.2 to 1 Oreochromis niloticus.m2 with feed and from 0.015 to 0.04 Oreochromis niloticus.m−2 without feed).If because of drought the water-retention cycle is lengthened from 180 to 320 days, the yield does not reduce too much.
Two independent productions (Heterotis and tilapia) and different consumers for each of them make the system more robust.
Moreover, Heterotis fry can be sold to generate additional income.Heterotis prevents the proliferation of molluscs, including the freshwater snails that are intermediate host of bilharzia (Bulinus sp.).
Less labour is required for the rice (no ploughing, little weeding). Water management in the dam pond ensures production (little risk of flooding or drought). The blocked water column eliminates weeds.
Rice limits the development of invasive aquatic plants (nenuphars, Pistias).
4 – Diversifying the commercial ecosystem services provided by aquaculture systems Because of the assurance of quality and freshness, local fish is prized by consumers and available all through the year. This new product – a large fish (1 to 2 kg per individual) – is also suitable for other types of consumption in the village (festive dishes of large families). The different productions are combined on the same site with the additional possibility of sales of fry. Rice is primarily produced for the family’s own cocase stnsumption, fish is mainly sold after satisfying the family’s basic needs.
A 60% increase in the overall annual value produced.