Olivier Mikolasek

Assessing aquaculture sustainability: a comparative methodology

Little work dealing with the evaluation of aquaculture system sustainability has so far been undertaken on a global and comparative basis. Moreover, such work is mostly based on very unbalanced approaches in terms of the dimensions of sustainable development that are taken into account. The approach adopted in this article is designed to encompass all the dimensions of sustainability including the institutional one (governance). The taking into account of this latter, in particular, together with the role played by aquaculture in sustainability at the territorial level gives the approach its original and innovative nature. The process of establishing the checklist of sustainability indicators in aquaculture relies on a hierarchical nesting approach which makes it possible to link indicators with general sustainability criteria and principles. At once multidisciplinary and participatory, the approach compares several countries with highly differentiated types of aquaculture system. An original finding from this work is that the technically most intensive farming model scores better than more extensive systems, which might have been thought to be closer to natural systems in their environmental dimension and therefore intuitively more ‘sustainable’. This result suggests relating sustainability outcomes to the level of control and of devolved responsibilities.

The Use of Wild Catfish (Clarias spp.) in Combination with Nile Tilapia (Oreochromis niloticus L.) in Western Cameroon: Technical Performances, Interests, and Limitations

Experiments on the use of catfish collected from the wild in polyculture with mixed sex tilapias were carried out between 2006 and 2009 in Western Cameroon. The objective was to develop an efficient and sustainable fish-farming model with local producers. Tilapia fingerlings of initial average weight of 5–20 g and catfish fingerlings of average weight 15–90 g were used at densities of 2 tilapias and 1 catfish per m². Fish nutrition was based mainly on organic fertilization of the ponds. Over three fish growing cycles, average survival rate of catfish was over 70%. The average yield obtained for each cycle was >3 t ha−1 year−1. Catfish represented nearly 50% of the total biomass harvested with individual final average weights of 235 ± 74 g, 284 ± 135 g, and 287 ± 133 g, for cycles I, II, and III, respectively. Male tilapias reached a final average weight of >200 g (277 ± 76; 245 ± 24; 212 ± 22). Geographical proximity to a source of catfish fingerlings constitutes the main determinate of adoption of this production system.

Evaluation of Aquaculture System Sustainability: A Methodology and Comparative Approaches

Over the last 30 years, aquaculture has experienced an unprecedented development in global animal production with an average yearly growth rate of over 10% between 1980 and 2000 (FAO, 2009). During the same period, capture fisheries saw their progression gradually grind to a standstill and growth stopped from 1995 (total catch fluctuating between 90 and 95 Mt/year according to the year). The growth of aquaculture, despite its benefits and the fact that it is the only way to meet the increase in demand for sea products, evaluated at 270Mt in 2050 (Chevassus au Louis et Lazard, 2009; Wijkstrom, 2003), raises a certain number of issues directly related to its sustainable development. Amongst these are issues related to feed for the farmed organisms, to their biological diversity, to the farms’ economic sustainability, to the impact of aquaculture development on social equity and to the set of arrangements constituting the sector’s governance. Feed, for example, is currently the subject of significant controversy as shown by the emblematic article of Naylor et al. (2000) that exposes the impact on catches of the massive use of fish meal and fish oil in fish and prawn aquaculture and advocates the return to sparser aquaculture systems, directly inspired by traditional Asian systems which use more extensive techniques based on polyculture and fertilisation and where artificial feed is only seen as a potential supplement. This diagnosis, although interesting as it generated much debate, was, however, incomplete and, in fact, inaccurate: by focusing on a single criterion and a single dimension (environmental) of sustainability, the authors were led to make proposals that had no chance of being adopted by the actors. De facto, farming systems have continued to intensify and this has led to a sustained increase in the use of

The Tanjona from Fenoarivo: Integrated fish farming systems in Madagascar

Fig. 3: Fenoarivo’s Tanjona, 1963 Results: 27 fish farmers were counted from Tanjona of Fenoarivo in 2016 Two typologies were identified (Fig. 4): 1) Tanjona with fish farming in ponds and culture on dykes 2) Tanjona with rice-fish aquaculture and culture on dykes Polyculture (carp, tilapia, snake head fish) Cycle of 6 to 12 months Fish stocking from caught in the neighbouring Sisaony Swamp or from rice plots Fish production: Study case: M. Dàdà is a farmer/fisherman from Fenoarivo. He own 12 rice plots of 0.76 ha, 3 Tanjona of 0.15 ha associated to oranges, leaves and sweet potatoes of which one is dedicated to fish farming (0.10 ha). He raises ducks and makes bricks every year. Fishing and fish farming: • Fish farming is realized on a pond (0.04 ha) • Fish stocking occurs from is own fishing activity (Nov. to May) • Fish are fed every 15 days with rice bran, maize, leaves, sweet potatoes and cow skin • Fertilization result from crops watering runoff • Fish production is about 300 kg/yr with a growth of 30 kg • Total fish growth is 714 kg/ha/cycle Synthesis of economical performances for each activity (Fig. 5):

Sustainability of fish pond culture in rural farming systems of Central and Western Cameroon

In Sub-Saharan Africa, fish ponds are often an integral part of farming systems but have suffered from a lack of viability and sustainability. The present study aims to understand the strategies used by fish farmers to overcome economic and environmental constraints. In 2008 and 2009, fish farmers were surveyed in Central and Western Cameroon, and the fish production systems were classified by cluster analysis. Four broad types were identified according to the complexity of household operations. The development of extensive systems (large-scale and low-input) in rural areas of central Cameroon is induced mainly by abundant available land. For semi-intensive systems in both regions (small-scale and high-input in the Western Region, large-scale and high-input in peri-urban areas of the Central Region), horizontal integration is not sufficient to make fish production profitable and sustainable. More intensive fish farms tend towards vertical integration, in which farmers establish close links with input suppliers. Main causes of low productivity of semi-intensive systems (1–2 t/ha/yr) are both lack of knowledge of fish farming principles by farmers and lack of technical improvement by extension agents and researchers which need to consider the local complexity of farming systems to develop and intensify fish production. The adaptation of development strategies to socio-economic and environmental contexts is a necessity to hope for an increase in fish pond aquaculture production in Africa.