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Nireka Weeratunge.

Fish in irrigation systems: an ancient practice may be the way of the future!

Compelling discussion, commentary, stories on agriculture within thriving ecosystems.

Fisheries are critically important to nutrition and food security around the world. The total global value of caught wild fish and aquaculture was estimated to be USD362 billion in 2016, with fish accounting for 17% of global animal protein consumption in 2015. In the lower Mekong alone, fisheries are estimated to be worth around $17 billion a year, supporting many millions of people living throughout the basin.

This critical source of income and nutrition is under threat. With rapid and sometimes destructive development, over-fishing, and extreme climatic events, once thriving breeding grounds like the Tonle Sap are rapidly degrading. As a result, it is anticipated that in many places fish catches and protein sources for local populations will likely fall in the coming years.

Irrigation – the bulk of which is in Asia – is more important than ever for producing food in the face of these changes, especially as a consequence of climate change, rainfall becomes more difficult to predict. Today, irrigated agriculture represents over 20% of cultivated agricultural land and contributes to about 40% of global crop production.

Ironically, irrigation infrastructure can adversely affect aquatic biodiversity and fish populations – by impeding the flow of rivers and obstructing breeding opportunities, or by creating oxygen-poor reservoirs where aquatic life can’t thrive. Many schemes suffer from poor maintenance, need constant rehabilitation and rarely operate at the levels originally anticipated.  Enhancing infrastructure solely to more effectively deliver water for increased crop production is no longer sufficient if the irrigation sector is to help achieve multiple sustainable development objectives. Modernizing irrigation schemes must now consider the sustainability and food security needs of our growing global population, and work on maximizing the benefits of irrigation for multiple users, all within the ecological limits of the ecosystems in which they are located.

Fish farming in irrigation systems is not a new practice, with recorded cases dating back two millennia. A new paper argues that explicitly integrating fisheries into irrigation systems as a part of irrigation modernization could be the key to achieving the contemporary demands on irrigation and enhancing global food security. The combined socio-economic and environmental benefits that could be derived are just the kind of win-win scenario we need if we are to achieve the Sustainable Development Goals (SDGs).

So what do we mean by modernization?

The study identifies two definitions of Irrigation Modernization, one from the Food and Agriculture Organization of the United Nations (FAO) and the other from the International Commission on Irrigation and Drainage (IDIC), that go beyond rehabilitation and see modernization as an upgrade or improvement, not only to infrastructure, but of operations and management of irrigation systems to achieve multiple goals. The ‘change process’ is envisaged to take place throughout the lifespan of irrigation systems, enabling them to adapt over time as societies' and farmers' requirements change. The ultimate aim is  to improve water services for farmers AND improve overall resource management.  

This requires a complete re-imagining of what irrigation modernization means. Improving services for farmers no longer means simply improving irrigation efficiency and increasing crop production. It now encompasses any service that provides nutrition, health, food and livelihood activities – including fisheries, aquaculture and other ecosystem services.

Have your fish and eat it too

The study, which was supported by the CGIAR Research Program on Water, Land and Ecosystems (WLE) and produced collaboratively with the International Water Management Institute (IWMI), WorldFish, and the CGIAR Research Program on FISH, proposes a framework for how fisheries can be better integrated into irrigation modernization at a variety of scales, from the scheme, to the catchment, and ultimately to the national level. Recognizing the many demands placed on the irrigation sector, the study suggests different ways to integrate fishery management into irrigation schemes, taking care to look at the local context, national food production and water usage goals.

For instance, in some areas, enhancing capture fisheries can be achieved by incorporating fish passes into scheme design, or changing gate design and operation to avoid injuring or killing fish that swim through them. In addition to the infrastructure change, these solutions require improved governance systems to ensure increased fisheries go to intended beneficiaries. Seeing governance as a part of the upgrade ensures a more holistic process of modernization, and ensures overall greater benefits for local irrigators and fisherfolk.

And it goes beyond fish capture. Aquaculture has great potential within irrigation schemes, either by using the water storage infrastructure that is constructed as part of the scheme, or in specifically built ponds located on farm plots. The second option could be in conjunction with irrigated rice farming (co-producing rice and aquatic protein in the same plot) or as a replacement to rice if the profit margin for fish is higher. Of course the sustainability of aquaculture is dependent on a number of factors, including good management, improved farmer capacity, and access to stable markets. All of these need to be assessed before investing in aquaculture within irrigation schemes.

Beyond the system level, to be truly sustainable, the kind of changes proposed need to take place within an enabling environment that takes into account catchment and national development and water strategies, as well as water and food needs. Instead of just improving efficiency of irrigation systems, adding fisheries can improve the value of water that can be re-used: once as a habitat for fish, and then as irrigation for crops, thereby increasing the overall productivity.  

By encouraging fisheries to flourish within irrigation systems, incomes within and beyond the system can be raised, water supply for multiple users can be ensured, biodiversity can be maintained, and food and nutritional security improved. By creating a more diverse set of benefits from irrigation systems, integrating fisheries into irrigation systems also has the potential to empower women or youth who might have more control over fish based nutrition or income within their families. It can even lead to reduced need for chemical fertilizers and pesticides, with fish and aquatic life taking the place of pest control while adding nutrient rich waste into the water to improve fertility, thereby reducing the environmental impact of agricultural systems.

So embrace the past in the process of irrigation modernization – incorporate fisheries for a winning combination.