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The potential of native species aquaculture to achieve conservation objectives: freshwater crayfish in Madagascar

The potential of native species aquaculture to achieve conservation objectives: freshwater... International Journal of Biodiversity Science and Management 3 (2007) 217–222 The potential of native species aquaculture to achieve conservation objectives: freshwater crayfish in Madagascar 1 2 1 J. P. G. Jones , F. B. Andriahajaina and N. Hockley School of the Environment and Natural Resources, University of Wales, Bangor Vokatry ny Ala, Fianarantsoa, Madagascar Key words: Astaciculture, crayfish, conservation, domestication, Integrated Conservation and Development Project (ICDP) SUMMARY Aquaculture of native species appeals to conservation projects in developing countries. It promises to raise local incomes while taking pressure off native stocks, without the risks associated with introducing exotic species into an area of conservation concern. We consider the case of native freshwater crayfish in Madagascar, a proposed target for native species aquaculture. We suggest three questions which should be considered by a conser- vation programme considering investment in such a project: 1) are the available species likely to be biologically suitable for aquaculture? 2) is aquaculture likely to be profitable relative to other land uses? 3) would successful aquaculture reduce wild harvesting? Using the available information on Malagasy crayfish and the local socio-economic context, we suggest that conservationists should focus limited funds on managing wild crayfish stocks. Research into native species whose characteristics make them suitable candidates for aquaculture should be encouraged. However, native species aquaculture is not a conser- vation panacea, and we suggest that, by considering available information, projects can avoid investing limited conservation resources in risky aquaculture schemes likely to have little conservation benefit. INTRODUCTION Most conservation projects working in develop- of ecological problems caused by the introduction ing countries recognise the importance of of exotic species (Leveque 1997; Tapia and improving the livelihoods of local people (Hutton Zambrano 2003) there is justified interest in the and Leader-Williams 2003; Adams et al. 2004). potential of native species for aquaculture (Ross and Aquaculture projects are attractive as they can Beveridge 1995; Connelly 2003; Grabowski et al. raise local incomes while increasing protein avail- 2003; Perez et al. 2003; Lindsay et al. 2006). Conser- ability and therefore improving people’s health vation projects are also increasingly considering (Ahmed and Lorica 2002). Due to the multitude aquaculture of native species as a way of taking Correspondence: Julia P. G. Jones, School of the Environment and Natural Resources, University of Wales, Bangor, Gwynedd LL57 2UW. Email: julia.jones@bangor.ac.uk 217 Native species aquaculture and conservation Jones et al. pressure off overexploited wild stocks (but see CRITERIA FOR SUCCESSFUL Naylor et al. 2000). NATIVE-SPECIES AQUACULTURE Madagascar’s endemic freshwater crayfish FOR CONSERVATION (Parastacidae; Astacoides) are found only in the 1. Are the available species likely to be forested eastern highlands of the island (Jones biologically suitable for aquaculture? et al. 2007). They are economically important to local communities (Jones et al. 2006), but Only a small proportion of species are suitable for there has been concern that the harvest is un- aquaculture. Of the 500-plus freshwater crayfish sustainable (Crandall 2003). The forests where the species in the world (Taylor 2002) for example, crayfish are found are under pressure from fewer than ten are cultivated commercially (Huner slash-and-burn agriculture (Green and Sussman and Lindqvist 1995). The commercial aquaculture 1990), making them the focus of numerous con- industry has well-established biological criteria for servation projects. As a result, the conservation identifying suitable candidates for aquaculture, community is interested in the potential of native among the most important of which are rapid freshwater crayfish aquaculture in Madagascar growth to marketable size and tolerance of a range (Dixon 1992; Wright and Andriamihaja 1993). of environmental conditions (Avault 1993; Le Currently the Association National pour la Francois et al. 2002; Wickins and Lee 2002). Gestion des Aires Protégées (ANGAP) are Detailed biological information on growth rates interested in investing in crayfish aquaculture and tolerance of environmental variance might not (astaciculture) in the periphery of national parks be available for a native aquaculture candidate spe- to help reduce the pressure on resources while cies, but any existing data and habitat requirements providing revenue to communities in compen- could provide useful information. Although sation for restricted access to the park (ANGAP growth rates in culture may be faster than under pers. com. 2004; Centre ValBio pers. com. 2005). wild conditions, wild growth rates can be used as an Despite ongoing interest, there has been no indication of likely growth in captivity (Quemener serious attempt to look critically at the biological et al. 2002). and economic feasibility of aquaculture of Good estimates of growth rates exist for only native crayfish in Madagascar. Aquaculture of one Astacoides species, Astacoides granulimanus, exotic crayfish is not being considered, given one of the most heavily harvested crayfish in that crayfish introductions have had extremely Madagascar. The growth rate of A. granulimanus, serious ecological impacts throughout the world estimated by a mark-and-recapture study involving (Lodge et al. 2000). We suggest three ques- 26,000 wild individuals over two years (Jones and tions which should be answered when considering Coulson 2006), is much slower than that of other a new species for aquaculture in the context commercially-important crayfish species (Table 1), of a conservation project, and consider these suggesting it might be difficult to make aquaculture for the case of freshwater crayfish aquaculture in economically viable. Preliminary data on other Madagascar. Astacoides species suggest their growth rates are likely to be just as slow (Jones et al. 2007). Table 1 The approximate time taken to reach a commercial size of 40 g by some crayfish species important in aquaculture compared with A. granulimanus Species Approx. time (months) to reach 40 g Reference Procambarus clarkii 9.6–14.4 Huner 2002 Cherax destructor 6–9 Lawrence and Jones 2002 Cherax quadricarinatus 6–9 Lawrence and Jones 2002 Cherax temuimanus < 12 Lawrence and Jones 2002 Pacifastacus leniusculus 24 Hogger 1986 A. granulimanus 62.4 (± 7.2 SEM) Jones and Coulson 2006 218 International Journal of Biodiversity Science and Management Native species aquaculture and conservation Jones et al. There is great variation in crayfish species’ toler- species such as A. granulimanus. A further problem ance to low-oxygen concentrations, with species is that even if land were available, sufficient water adapted to ephemeral, warm water bodies more may be limiting. Although the eastern rain forests −1 resistant than species found in well-oxygenated have relatively high rainfall (1700–4300 mm y ), habitats (Nyström 2002). The main habitat of the rainfall is seasonal and there are times of year A. granulimanus is fast-flowing mountain streams when water to irrigate rice fields is limiting (Wright in forested watersheds; as such it is unlikely to be and Andriamihaja 1993). In our small-scale trials resistant to oxygen levels much below saturation. with A. granulimanus in irrigated earthen tanks, Could other Astacoides species be better suited to egg-bearing females suffered complete eggs loss aquaculture? A. crosnieri is found mostly in swampy, and significant mortality during a period of water temporarily flooded habitats (Dixon 1992) and so scarcity, probably due to the elevated water temper- may be more tolerant of low-oxygen concentra- ature and low-oxygen content caused by the poor tions. However, this species’ small size and ‘muddy’ water flow (Jones J.P.G. unpublished data). taste and colouration mean it is not commonly eaten and has a very low market value (Jones et al. 3. Would successful aquaculture reduce 2006). wild harvesting? One of the difficulties facing any project aiming to 2. Is aquaculture likely to be profitable take pressure off wild populations by promoting relative to other land uses? aquaculture is the challenge of turning fishermen Even if a species could theoretically be grown at into farmers. Around the world, uptake of new a profit, where land is limited, aquaculture must aquaculture techniques tends to be higher among produce greater economic returns per ha than richer people (Stonich et al. 1997; Tapia and competing land uses to be economically viable. Zambrano 2003), whereas those currently exploit- Extensive crayfish aquaculture needs land that is ing wild stocks may belong to poorer sections of flat and poorly drained, with sufficient fertility in society. Very poor people tend to be risk-averse and the top soil to allow a rich growth of vegetation for not to have sufficient available resources (capital or crayfish fodder (Huner 1989). Such land in the labour) to invest in an unproven project (Ellis 1993: eastern rainforests of Madagascar is scarce due to chapter 5). the mountainous terrain. In fact, rice produc- The people of the eastern rain forests are some tion (the main agricultural activity) is limited by of the poorest in Madagascar; more than 88% of inadequate suitably irrigated land (Wright and rural people in Fianarantsoa Province live on less Andriamihaja 1993). Irrigated rice in upland Mada- than $150 a year (INSTAT 2002). Those involved in −1 gascar produces on average 1.9 ton ha (Fujisaka crayfish harvesting are among the poorest house- 1990), but under improved techniques, yields in holds in the area. They claim that one of the reasons −1 the eastern rain forest regularly reach 3.9 ton ha they harvest crayfish is lack of resources for invest- (LDI 2003). Using the mean rice price for 2003 in ment in agriculture (Jones et al. 2006). People who the region (INSTAT 2004), and an exchange rate of do not invest in irrigated rice production, a profit- US$1 = 5830 FMG, this equates to $570 and $1264, able activity with a proven history, a guaranteed respectively. A. granulimanus sold raw at the point market and cultural acceptability, may be unlikely −1 of harvest are worth approximately $0.77 kg to invest in a new aquaculture innovation. (Jones et al. 2006). Astaciculture must therefore Although some successful crayfish aquaculture −1 produce more than 741 to 1605 kg ha to compete enterprises use very low inputs, effort is still with rice. This is assuming that the crayfish price required to dig and maintain tanks and in initial does not fall with increasing production, an unreal- stocking. Emigration of crayfish, especially signifi- istic assumption when we consider the limited cant at commercially viable stocking densities, is a market opportunities due to the very poor trans- serious problem facing all crayfish farmers. In port infrastructure in rural Madagascar. Although intensive production, fencing is used (Huner 2002; established aquaculture enterprises with well Lawrence and Jones 2002) but this would be pro- known commercial species can reach such levels of hibitively expensive in the rural Malagasy context. productivity, they are unlikely for a slow-growing Many astaciculture enterprises do not use fences, International Journal of Biodiversity Science and Management 219 Native species aquaculture and conservation Jones et al. but fences are often large, with one owner main- result in a reduction in wild harvesting. Before taining many tens or even hundreds of hectares of limited conservation resources are invested, pro- ponds (Huner 2002). The degree to which cray- jects should look at whether the proposed species is fish travel overland varies between species; we have likely to be a suitable aquaculture candidate, and little information on the overland movements in whether successful aquaculture is likely to take Astacoides, but preliminary evidence from aqua- pressure off wild stocks. culture trials suggests that they are very willing to The poverty of many rural people in eastern leave tanks and move overland. In the context of Madagascar, and their reliance on slash-and-burn Malagasy farming systems, where average land agriculture and harvesting of products from the holdings per farmer are less than 0.5 ha (INSTAT fast-disappearing forests has resulted in under- 2002), crayfish mobility represents a serious standable enthusiasm to identify alternative problem. income-generating activities. Crayfish aquaculture, A study in the Ranomafana area (Razafimamonjy however, is difficult to make economically viable 1996) found that poorer villagers were unwilling to (Staniford 1989; Huner and Lindqvist 1995; invest in aquaculture systems, even when loans were Lawrence and Jones 2002) even where suitable available to cover the initial costs. It may, therefore, species, well-developed farming techniques, mar- be naïve to assume that successful introduction of ket demand, ample appropriate land, and capital native species aquaculture would take pressure off for investment are available. Our knowledge of the wild stocks. biology of Madagascar’s native crayfish is still woefully limited (Crandall 2003) so it is possible that further research will identify suitable species CONCLUSIONS and methods for successful aquaculture. However, The damaging ecological effects of some aqua- we suggest that existing knowledge is enough to culture programmes, particularly intensive schemes conclude that astaciculture of native crayfish in producing high-value products for export, are Madagascar is unlikely to be successful within the increasingly recognised (Leveque 1997; Lebel et al. current socio-economic framework. Wild harvest- 2002). Aquaculture projects have often failed to ing of crayfish in Madagascar can be sustainably consider the potential of native species, and this managed (Jones et al. 2005), and we suggest that may have resulted in unnecessary ecologically- conservation resources should, instead, be focussed damaging introductions (Perez et al. 2003). We do on improving management of wild stocks. not wish to discourage investment in native species aquaculture where available species have real ACKNOWLEDGEMENTS commercial potential (see Ross et al. 2006). How- ever, developing a native species for aquaculture In Madagascar we thank ANGAP, Miray Mahefa, requires considerable investment in research and the Département des Eaux et Forêts, Ecoregional experimental trials and is not an easy option for Interventions and Vokatry ny Ala. JPGJ was conservation projects. In fact, where overexploita- funded by the UK Natural Environment Research tion in the wild has led to interest in aquaculture, Council and the fieldwork was supported by the this may be especially true; species vulnerable to Rufford Maurice Laing Foundation and North- overharvesting may be slow-growing and so are western Marine Technology. We also thank unlikely to be suitable aquaculture candidates. Andrew Balmford, Mark Freudenberger, Anicet Even where a species can be successfully cultured, Ranaivoarison, Jeanne Rasamy and Olga socio-economic realities may mean this will not Ravoahangimalala. REFERENCES Adams WM, Aveling R, Brockington D, Dickson B, Ahmed M and Lorica MH. Improving developing Elliott J, Hutton J, Roe D, Vira B and Wolmer W. country food security through aquaculture devel- Biodiversity conservation and the eradication of opment-lessons from Asia. Food Policy 2002;27: poverty. Science 2004;306:1146–9 125–41 220 International Journal of Biodiversity Science and Management Native species aquaculture and conservation Jones et al. Avault JW. Ten requirements for culturing a ‘new’ INSTAT. Evolution de l’indice des prix da la consommation species: a checklist. Aquaculture Magazine 1993; familiale. Antananarivo Madagascar: Institut 19:73–8 National de la Statistique (INSTAT); 2004 Connelly J. Congressional testimony of the President Jones JPG, Andriahajaina FB, Hockley NJ, Balmford A of the National Fisheries Institute on invasive and Ravoahangimalala OR. A multidisciplinary species. In US House of Representatives, Committee on approach to assessing the sustainability of fresh- Resouces, Oceans, Fisheries and Wildlife Conservation water crayfish harvesting in Madagascar. Conserva- Subcommittee; 2003 tion Biology 2005;19:1863–71 Crandall K. Parastacidae, Astacoides, freshwater cray- Jones JPG, Andriahajaina FB, Hockley NJ, Crandall KA fishes. In Goodman SM and Benstead JP (eds), The and Ravoahangimalala. OR. The ecology and con- Natural History of Madagascar. Chicago USA: servation status of Madagascar’s endemic fresh- University of Chicago Press; 2003:608–12 water crayfish (Parastacidae; Astacoides) Freshwater Dixon H. Species identification and described habitats of the Biology 2007;52:1820–33 crayfish genus Astacoides (Decapoda: Parastacidae) in Jones JPG, Andriahajaina FB, Ranambinintsoa EH, the Ranomafana National Park region of Madagascar. Hockley NJ and Ravoahangimalala O. 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LDI annual report: overview and LDI regular activi- native (Crassostrea virginica) oysters. Journal of Shell- ties. Antananarivo Madagascar: Landscape Devel- fish Research 2003;22:21–30 opment Interventions (USAID); 2003 Green GM and Sussman RW. Deforestation history Le Francois NR, Lemieux H and Blier PU. Biological of the eastern rainforests of Madagascar from and technical evaluation of the potential of marine satellite images. Science 1990; 248:212–15 and anadromous fish species for cold-water mari- Hogger JB. Aspects of the introductions of ‘signal cray- culture. Aquaculture Research 2002;33:95–108 fish’ Pacifastacus leniusculus in the southern United Lebel L, Tri NH, Saengnoree A, Pasong S, Buatama U Kingdom. 1) Growth and Survival. Aquaculture and Thoa LK. Industrial transformation and 1986;58:27–44 shrimp aquaculture in Thailand and Vietnam: Huner JV. Overview of international and domestic pathways to ecological, social, and economic freshwater crayfish production. 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Oxford UK: Blackwell Science; on the economic feasibility of freshwater crayfish 2002:192–235 Cherax destructor Clark (Decapoda: Parastacidae) Pérez JE, Alfonsi C, Nirchio M, Munoz C and Gomez production in Australia. Aquaculture 1989;81: JA. The introduction of exotic species in aqua- 225–35 culture: A solution or part of the problem? Stonich SC, Bort JR and Ovares LL. Globalization of Interciencia 2003;28:234–8 shrimp mariculture: The impact on social justice Quéméner L, Suquet M, Mero D and Gaignon JL. and environmental quality in Central America. Selection method of new candidates for finfish Society & Natural Resources 1997;10:161–79 aquaculture: the case of the French Atlantic, the Tapia M and Zambrano L. From aquaculture goals Channel and the North Sea coasts. Aquatic Living to real social and ecological impacts: Carp intro- Resources 2002;15:293–302 duction in rural Central Mexico. Ambio 2003; Razafimamonjy D. Integrating biological conservation 32:252–7 and economic development: finding the linkages in the Taylor CA. Taxonomy and conservation of native southern rainforest of Madagascar. Antananarivo crayfish stocks. In Holdich DM (ed.), Biology of Madagascar: National Center for Environmental Freshwater Crayfish. Oxford UK: Blackwell Science; Research; 1996 2002:236–57 Ross LG and Beveridge MCM. Is a better strategy Wickins JF and Lee D. Crustacean farming: ranching necessary for development of native species for and culture. Oxford UK: Blackwell Science; 2002 aquaculture? a Mexican case study. Aquaculture Wright P and Andriamihaja B. Ranomafana National Research 1995;26:539–47 Park Integrated Conservation and Development Project. Ross LG, Martinez-Palacios CM, Sousa MLRD and Antananarivo Madagascar: Stony Brook Univer- Campos-Mendoza A. The Darwin Initiative and the sity, Association Tefy Saina, Cornell University; whitefish Chirostoma estor estor: a link between 1993:71 pp. 222 International Journal of Biodiversity Science and Management http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png International Journal of Biodiversity Science & Management Taylor & Francis

The potential of native species aquaculture to achieve conservation objectives: freshwater crayfish in Madagascar

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International Journal of Biodiversity Science and Management 3 (2007) 217–222 The potential of native species aquaculture to achieve conservation objectives: freshwater crayfish in Madagascar 1 2 1 J. P. G. Jones , F. B. Andriahajaina and N. Hockley School of the Environment and Natural Resources, University of Wales, Bangor Vokatry ny Ala, Fianarantsoa, Madagascar Key words: Astaciculture, crayfish, conservation, domestication, Integrated Conservation and Development Project (ICDP) SUMMARY Aquaculture of native species appeals to conservation projects in developing countries. It promises to raise local incomes while taking pressure off native stocks, without the risks associated with introducing exotic species into an area of conservation concern. We consider the case of native freshwater crayfish in Madagascar, a proposed target for native species aquaculture. We suggest three questions which should be considered by a conser- vation programme considering investment in such a project: 1) are the available species likely to be biologically suitable for aquaculture? 2) is aquaculture likely to be profitable relative to other land uses? 3) would successful aquaculture reduce wild harvesting? Using the available information on Malagasy crayfish and the local socio-economic context, we suggest that conservationists should focus limited funds on managing wild crayfish stocks. Research into native species whose characteristics make them suitable candidates for aquaculture should be encouraged. However, native species aquaculture is not a conser- vation panacea, and we suggest that, by considering available information, projects can avoid investing limited conservation resources in risky aquaculture schemes likely to have little conservation benefit. INTRODUCTION Most conservation projects working in develop- of ecological problems caused by the introduction ing countries recognise the importance of of exotic species (Leveque 1997; Tapia and improving the livelihoods of local people (Hutton Zambrano 2003) there is justified interest in the and Leader-Williams 2003; Adams et al. 2004). potential of native species for aquaculture (Ross and Aquaculture projects are attractive as they can Beveridge 1995; Connelly 2003; Grabowski et al. raise local incomes while increasing protein avail- 2003; Perez et al. 2003; Lindsay et al. 2006). Conser- ability and therefore improving people’s health vation projects are also increasingly considering (Ahmed and Lorica 2002). Due to the multitude aquaculture of native species as a way of taking Correspondence: Julia P. G. Jones, School of the Environment and Natural Resources, University of Wales, Bangor, Gwynedd LL57 2UW. Email: julia.jones@bangor.ac.uk 217 Native species aquaculture and conservation Jones et al. pressure off overexploited wild stocks (but see CRITERIA FOR SUCCESSFUL Naylor et al. 2000). NATIVE-SPECIES AQUACULTURE Madagascar’s endemic freshwater crayfish FOR CONSERVATION (Parastacidae; Astacoides) are found only in the 1. Are the available species likely to be forested eastern highlands of the island (Jones biologically suitable for aquaculture? et al. 2007). They are economically important to local communities (Jones et al. 2006), but Only a small proportion of species are suitable for there has been concern that the harvest is un- aquaculture. Of the 500-plus freshwater crayfish sustainable (Crandall 2003). The forests where the species in the world (Taylor 2002) for example, crayfish are found are under pressure from fewer than ten are cultivated commercially (Huner slash-and-burn agriculture (Green and Sussman and Lindqvist 1995). The commercial aquaculture 1990), making them the focus of numerous con- industry has well-established biological criteria for servation projects. As a result, the conservation identifying suitable candidates for aquaculture, community is interested in the potential of native among the most important of which are rapid freshwater crayfish aquaculture in Madagascar growth to marketable size and tolerance of a range (Dixon 1992; Wright and Andriamihaja 1993). of environmental conditions (Avault 1993; Le Currently the Association National pour la Francois et al. 2002; Wickins and Lee 2002). Gestion des Aires Protégées (ANGAP) are Detailed biological information on growth rates interested in investing in crayfish aquaculture and tolerance of environmental variance might not (astaciculture) in the periphery of national parks be available for a native aquaculture candidate spe- to help reduce the pressure on resources while cies, but any existing data and habitat requirements providing revenue to communities in compen- could provide useful information. Although sation for restricted access to the park (ANGAP growth rates in culture may be faster than under pers. com. 2004; Centre ValBio pers. com. 2005). wild conditions, wild growth rates can be used as an Despite ongoing interest, there has been no indication of likely growth in captivity (Quemener serious attempt to look critically at the biological et al. 2002). and economic feasibility of aquaculture of Good estimates of growth rates exist for only native crayfish in Madagascar. Aquaculture of one Astacoides species, Astacoides granulimanus, exotic crayfish is not being considered, given one of the most heavily harvested crayfish in that crayfish introductions have had extremely Madagascar. The growth rate of A. granulimanus, serious ecological impacts throughout the world estimated by a mark-and-recapture study involving (Lodge et al. 2000). We suggest three ques- 26,000 wild individuals over two years (Jones and tions which should be answered when considering Coulson 2006), is much slower than that of other a new species for aquaculture in the context commercially-important crayfish species (Table 1), of a conservation project, and consider these suggesting it might be difficult to make aquaculture for the case of freshwater crayfish aquaculture in economically viable. Preliminary data on other Madagascar. Astacoides species suggest their growth rates are likely to be just as slow (Jones et al. 2007). Table 1 The approximate time taken to reach a commercial size of 40 g by some crayfish species important in aquaculture compared with A. granulimanus Species Approx. time (months) to reach 40 g Reference Procambarus clarkii 9.6–14.4 Huner 2002 Cherax destructor 6–9 Lawrence and Jones 2002 Cherax quadricarinatus 6–9 Lawrence and Jones 2002 Cherax temuimanus < 12 Lawrence and Jones 2002 Pacifastacus leniusculus 24 Hogger 1986 A. granulimanus 62.4 (± 7.2 SEM) Jones and Coulson 2006 218 International Journal of Biodiversity Science and Management Native species aquaculture and conservation Jones et al. There is great variation in crayfish species’ toler- species such as A. granulimanus. A further problem ance to low-oxygen concentrations, with species is that even if land were available, sufficient water adapted to ephemeral, warm water bodies more may be limiting. Although the eastern rain forests −1 resistant than species found in well-oxygenated have relatively high rainfall (1700–4300 mm y ), habitats (Nyström 2002). The main habitat of the rainfall is seasonal and there are times of year A. granulimanus is fast-flowing mountain streams when water to irrigate rice fields is limiting (Wright in forested watersheds; as such it is unlikely to be and Andriamihaja 1993). In our small-scale trials resistant to oxygen levels much below saturation. with A. granulimanus in irrigated earthen tanks, Could other Astacoides species be better suited to egg-bearing females suffered complete eggs loss aquaculture? A. crosnieri is found mostly in swampy, and significant mortality during a period of water temporarily flooded habitats (Dixon 1992) and so scarcity, probably due to the elevated water temper- may be more tolerant of low-oxygen concentra- ature and low-oxygen content caused by the poor tions. However, this species’ small size and ‘muddy’ water flow (Jones J.P.G. unpublished data). taste and colouration mean it is not commonly eaten and has a very low market value (Jones et al. 3. Would successful aquaculture reduce 2006). wild harvesting? One of the difficulties facing any project aiming to 2. Is aquaculture likely to be profitable take pressure off wild populations by promoting relative to other land uses? aquaculture is the challenge of turning fishermen Even if a species could theoretically be grown at into farmers. Around the world, uptake of new a profit, where land is limited, aquaculture must aquaculture techniques tends to be higher among produce greater economic returns per ha than richer people (Stonich et al. 1997; Tapia and competing land uses to be economically viable. Zambrano 2003), whereas those currently exploit- Extensive crayfish aquaculture needs land that is ing wild stocks may belong to poorer sections of flat and poorly drained, with sufficient fertility in society. Very poor people tend to be risk-averse and the top soil to allow a rich growth of vegetation for not to have sufficient available resources (capital or crayfish fodder (Huner 1989). Such land in the labour) to invest in an unproven project (Ellis 1993: eastern rainforests of Madagascar is scarce due to chapter 5). the mountainous terrain. In fact, rice produc- The people of the eastern rain forests are some tion (the main agricultural activity) is limited by of the poorest in Madagascar; more than 88% of inadequate suitably irrigated land (Wright and rural people in Fianarantsoa Province live on less Andriamihaja 1993). Irrigated rice in upland Mada- than $150 a year (INSTAT 2002). Those involved in −1 gascar produces on average 1.9 ton ha (Fujisaka crayfish harvesting are among the poorest house- 1990), but under improved techniques, yields in holds in the area. They claim that one of the reasons −1 the eastern rain forest regularly reach 3.9 ton ha they harvest crayfish is lack of resources for invest- (LDI 2003). Using the mean rice price for 2003 in ment in agriculture (Jones et al. 2006). People who the region (INSTAT 2004), and an exchange rate of do not invest in irrigated rice production, a profit- US$1 = 5830 FMG, this equates to $570 and $1264, able activity with a proven history, a guaranteed respectively. A. granulimanus sold raw at the point market and cultural acceptability, may be unlikely −1 of harvest are worth approximately $0.77 kg to invest in a new aquaculture innovation. (Jones et al. 2006). Astaciculture must therefore Although some successful crayfish aquaculture −1 produce more than 741 to 1605 kg ha to compete enterprises use very low inputs, effort is still with rice. This is assuming that the crayfish price required to dig and maintain tanks and in initial does not fall with increasing production, an unreal- stocking. Emigration of crayfish, especially signifi- istic assumption when we consider the limited cant at commercially viable stocking densities, is a market opportunities due to the very poor trans- serious problem facing all crayfish farmers. In port infrastructure in rural Madagascar. Although intensive production, fencing is used (Huner 2002; established aquaculture enterprises with well Lawrence and Jones 2002) but this would be pro- known commercial species can reach such levels of hibitively expensive in the rural Malagasy context. productivity, they are unlikely for a slow-growing Many astaciculture enterprises do not use fences, International Journal of Biodiversity Science and Management 219 Native species aquaculture and conservation Jones et al. but fences are often large, with one owner main- result in a reduction in wild harvesting. Before taining many tens or even hundreds of hectares of limited conservation resources are invested, pro- ponds (Huner 2002). The degree to which cray- jects should look at whether the proposed species is fish travel overland varies between species; we have likely to be a suitable aquaculture candidate, and little information on the overland movements in whether successful aquaculture is likely to take Astacoides, but preliminary evidence from aqua- pressure off wild stocks. culture trials suggests that they are very willing to The poverty of many rural people in eastern leave tanks and move overland. In the context of Madagascar, and their reliance on slash-and-burn Malagasy farming systems, where average land agriculture and harvesting of products from the holdings per farmer are less than 0.5 ha (INSTAT fast-disappearing forests has resulted in under- 2002), crayfish mobility represents a serious standable enthusiasm to identify alternative problem. income-generating activities. Crayfish aquaculture, A study in the Ranomafana area (Razafimamonjy however, is difficult to make economically viable 1996) found that poorer villagers were unwilling to (Staniford 1989; Huner and Lindqvist 1995; invest in aquaculture systems, even when loans were Lawrence and Jones 2002) even where suitable available to cover the initial costs. It may, therefore, species, well-developed farming techniques, mar- be naïve to assume that successful introduction of ket demand, ample appropriate land, and capital native species aquaculture would take pressure off for investment are available. Our knowledge of the wild stocks. biology of Madagascar’s native crayfish is still woefully limited (Crandall 2003) so it is possible that further research will identify suitable species CONCLUSIONS and methods for successful aquaculture. However, The damaging ecological effects of some aqua- we suggest that existing knowledge is enough to culture programmes, particularly intensive schemes conclude that astaciculture of native crayfish in producing high-value products for export, are Madagascar is unlikely to be successful within the increasingly recognised (Leveque 1997; Lebel et al. current socio-economic framework. Wild harvest- 2002). Aquaculture projects have often failed to ing of crayfish in Madagascar can be sustainably consider the potential of native species, and this managed (Jones et al. 2005), and we suggest that may have resulted in unnecessary ecologically- conservation resources should, instead, be focussed damaging introductions (Perez et al. 2003). We do on improving management of wild stocks. not wish to discourage investment in native species aquaculture where available species have real ACKNOWLEDGEMENTS commercial potential (see Ross et al. 2006). How- ever, developing a native species for aquaculture In Madagascar we thank ANGAP, Miray Mahefa, requires considerable investment in research and the Département des Eaux et Forêts, Ecoregional experimental trials and is not an easy option for Interventions and Vokatry ny Ala. JPGJ was conservation projects. In fact, where overexploita- funded by the UK Natural Environment Research tion in the wild has led to interest in aquaculture, Council and the fieldwork was supported by the this may be especially true; species vulnerable to Rufford Maurice Laing Foundation and North- overharvesting may be slow-growing and so are western Marine Technology. We also thank unlikely to be suitable aquaculture candidates. Andrew Balmford, Mark Freudenberger, Anicet Even where a species can be successfully cultured, Ranaivoarison, Jeanne Rasamy and Olga socio-economic realities may mean this will not Ravoahangimalala. REFERENCES Adams WM, Aveling R, Brockington D, Dickson B, Ahmed M and Lorica MH. 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The Darwin Initiative and the sity, Association Tefy Saina, Cornell University; whitefish Chirostoma estor estor: a link between 1993:71 pp. 222 International Journal of Biodiversity Science and Management

Journal

International Journal of Biodiversity Science & Management – Taylor & Francis

Published: Dec 1, 2007

Keywords: ASTACICULTURE; CRAYFISH; CONSERVATION; DOMESTICATION; INTEGRATED CONSERVATION AND DEVELOPMENT PROJECT (ICDP)

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