Enhancing benefits from polycultures including tilapia (Oreochromis niloticus) within integrated pond-dike systems: A participatory trial with households of varying socio-economic level in rural and peri-urban areas of Bangladesh

Abstract

Linkages between the fish ponds and surrounding land for horticulture are a distinctive feature of farming households in Bangladesh. It was hypothesised that integration of fish ponds in integrated farming system enhances livelihoods and reduces poverty. The effects of introducing tilapia into existing integrated farming systems on the broader pond-dike system and associated livelihoods in rural and peri-urban settlements in central north (Mymensingh District) of Bangladesh were evaluated.

Farmer participatory research carried out during June 2004 to March 2005 showed that production of fish could be substantially increased by increasing nutrient inputs rather than by stocking tilapia as an additional species. However, the ‘improved’ nutrient input applied by farmers was still well below the level required for optimal tilapia performance. Rural households benefited more than peri-urban households through enhanced direct consumption of fish and vegetables. In contrast, peri-urban households benefited more through cash sales of both fish and vegetables than rural households. Households with access to ponds, identified as relatively better-off and worse-off in the researched communities benefited equally selling and consuming fish and vegetable. Similar production levels of vegetable production between groups applying different fish culture practises suggesting that increased investment in fish production is complementary rather than competitive to vegetable production in integrated pond-dike farming systems. It was concluded that considerable potential exists to further develop pond-dike systems, which would improve livelihoods of both better-off and worse-off producers. Reference is made to the potential impacts of such changes in integrated pond-dike management if promoted more widely in Bangladesh.

Introduction

Recently, Bangladesh made considerable improvements in fish culture technology, particularly in pond-based systems (Karim, 2006, Faruque, 2007, Jahan et al., 2010). though, due to a variety of reasons, fish production has not kept pace with demand (Lewis, 1998, Ahmed and Chowdhury, 1999, ADB., 2005). The contribution of fish to the country's total animal protein intake has been declining over the years, but is still the most important source of animal protein in the Bangladeshi diet, contributing 63% of total animal protein consumption (Ahmed, 2005).

There have been two major directions to aquaculture development in Asia in the last decades; conventional intensification and system integration (Edwards et al., 1997, Michielsens et al., 2002). Closer and more strategic integration within the broader farming or livelihood system, where the pond becomes a focus for diversification and enhanced nutrient and water use efficiencies (Integrated Aquaculture–Agriculture (IAA) Systems), has become an important phenomenon in Asia (Nhan et al., 2007). In contrast, intensification can also focus on fish production itself, specialising in higher levels and careful management of inputs. Both approaches are evident in Bangladesh and can be combined for greater benefit.

Intensification started in earnest recently beginning with coastal shrimp culture in ponds and later in striped catfish pangasius (Pangasianodon hypopthalmus) culture. More recently, there has been an increasing interest in intensive tilapia monoculture in ponds in Bangladesh (Edwards and Karim, 2006). However, the pre-dominant form of aquaculture still remains extensive and semi-intensive carp polyculture, much of which is limited by lack of nutrients and integrated, to a variable degree, with surrounding agriculture. The potential for inclusion of the phytophagous Nile tilapia within carp polyculture remains undeveloped in Bangladesh, despite this being a major mechanism of intensification in some other Asian countries which were previously dependent on carp polyculture (Little and Bunting, 2005). Tilapia-dominant polycultures perform best when receiving higher levels of fertilisation (Hossain et al., 2003) and this might explain their popularity in peri-urban areas where wastes and other by-products are more cost effectively available.

The positive impacts on poverty of aquaculture development in Bangladesh have frequently been challenged (Lewis, 1997) as the practise is intrinsically linked to access to land and other resources. However, recent studies suggest that many poorer people are benefiting from increased aquaculture production in a variety of ways (Faruque et al., 2006, Little et al., 2007). Small ponds, either owned or leased, are common assets among poorer households partly for fish culture but also for a variety of other purposes including irrigation of vegetables (Little, 2000, Little et al., undated, Little et al., 2007).

Pond fertilisation and feeding increases production of natural fish food organisms in ponds (Singh, 1984, Milstein, 1993). Nevertheless, only 5–30% of the nutrients added in this way are converted into harvestable products (Edwards, 1993), the remainder is lost to the pond water or accumulates in the sediment. The latter can be used, along with pond water to simultaneously fertilise and irrigate, to ‘fertigate’ the surrounding vegetable crops could potentially benefit households through subsistence food and income generation (Little and Muir, 1987). Unfortunately, there are few quantitative studies that document this practise.

Promotion of IAA has become central to aquaculture extension efforts to resource poor farmers in Bangladesh. IAA systems, including rice–fish (Haroon et al., 1992, Ali et al., 1999, Bhuiyan, 1999), poultry–fish (Ali et al., 1995, Samsuzzaman, 2002, Little and Edwards, 2003), duck-cum-fish (Ali et al., 1995) and duck–weed–fish based systems (Azim and Wahab, 1998, Wahab et al., 2001) have been promoted. In Bangladesh, vegetable production on pond-dike yields better economic benefits than fish culture alone (Shamsuddoha and Janssen, 2003) and may be more attractive to poorer households. As shown by a study on Bhola island, dike cropping of vegetables was a preferred option of the poorer households, while better-off households tended to prefer intensification of carp polyculture (Shamsuddoha and Janssen, 2003). In the integrated pond-dike system, poorer households irrigated vegetable gardens with pond water while fertile homestead run-off increased pond water fertility. Vegetable production on dikes also provided leaves for use as feed for grass carp within the polyculture systems (Shamsuddoha and Janssen, 2003). In addition, Karim (2006) demonstrated that the culture intensity in ponds and on dikes was significantly higher for pond-dike systems in peri-urban areas than in rural areas. Such forms of IAA have a high potential for improving rural and peri-urban livelihoods of poor smallholder households (Talukder et al., 2001, Hossain, 2003).

It is generally accepted that the behaviour of better-off and worse off small-scale farmers in developing countries is based on ‘economic’ incentives, however factors such as location, production systems, supply, demand and marketing systems should also be considered (Edwards and Demaine, 1997). In this context, insight into the role of pond-dike systems in the overall livelihoods of better-off and worse off farming households and the importance of location is largely lacking.

This paper describes a participatory trial with farming households aggregated by well-being (better-off and worse-off) and location (peri-urban and rural) practising integrated pond-dike farming. Outcomes were monitored over a full production cycle of a control group (1) compared to households choosing to stock Nile tilapia as an additional species within their standard polyculture systems using either the same levels (2) or enhanced levels (3) of nutrient input.