Aquaculture for all

Six ways to make your aquaculture operations more climate-resilient

Shrimp Climate change Catfish / Pangasius +10 more

Sharing practical tips for small-scale aquaculture operators, particularly those based in the tropics, to adapt and become more resilient to the changing climate and extreme weather events.

by Aquaculture consultant
Kyra Hoevenaars thumbnail
Aquaculture consultant
Jonah van Beijnen thumbnail
Aerial view of houses along a flooded riverbank.
A floating village on the Hau River in Vietnam, one of the country's key pangasius producing areas

Extreme weather events are putting aquaculture operations at risk

Most fish and shrimp farms are heavily dependent on environmental conditions, especially the provision of clean water at a stable temperature, and this makes them especially vulnerable to the impacts of a changing climate.

The main climate stressors that affect aquaculture are temperature fluctuations, changes in rainfall patterns that cause floods or droughts, and increased storm variability and severity. Marine aquaculture is also affected by ocean acidification and the increased occurrence of harmful algal blooms (HABs). Impacts differ, depending on the farmed species, the farm environment, the type of farming system and the geographical location. Impacts can occur in a very short time (i.e. heavy rainfall), while other are long-term trends, with change happening gradually over time (i.e. ocean acidification).

Ninety percent of aquaculture operations face risks from environmental change. Some of the countries with the highest climate risks – mostly in Asia, Latin America and Africa – have the lowest capacity to adapt to the changes in climate.

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A good example is Myanmar. In May 2023, Cyclone Mocha hit the southern Bay of Bengal, with the centre of the storm near Sittwe City in Rakhine State. This was one of the most powerful storms to have ever been recorded in the region, with winds reaching 259 kilometres per hour, and an estimated 670,000 hectares of land were flooded, impacting livelihoods and food security of the already poverty-stricken regions. Over a million people from an estimated 237,000 households were impacted, including many fish and shrimp farmers. Stock was lost and infrastructure destroyed. The UN estimated that two in every three farming households and more than one in every three fishing households in the area lost their productive assets. The total economic loss has been calculated at US$ 2.24 billion, which is the equivalent to 3.4 percent of Myanmar's GDP.

Similarly in 2021, Indian shrimp famers were struck by Cyclone Yaas, losing around 12,000 tonnes of shrimp (valued at USD 130 million). It was hard for farmers to start again, since some had loans to pay off on top of the losses of shrimp and infrastructure.

Marine farms are also regularly hit by more severe storms that seem to have been increasing in recent years. In Scotland 50,000 salmon escaped after damage to the nets by storm Ellen in 2020 and in Chile between 500,000 and 800,000 fish escaped due to storm damages. Damage to floating cages in Thailand by the tsunami in 2005 amounted to USD 32.7 million, with over 40,000 cages destroyed.

Effects of climate change are highly unpredictable and extremely localised, complicating things further. While some areas will experience more rainfall, others are impacted by more severe droughts or more frequent and bigger storms. Therefore, adaptation measures should be adjusted to suit local circumstances, as different threats need different adaptation options. In principle, the goal is that all adaptation measures should be designed to reduce vulnerability and effectively adapt to the climate impact. Selection of effective adaptation measures also depends on community acceptance, the urgency of implementation, technical feasibility, ease of implementation and the costs required to implement the measures.

In this article we provide general tips for small-scale farmers to follow when starting an aquaculture farm or when adapting their farm to the changing climate. Doris Soto, who has worked for the United Nation’s Food and Agricultural Organization (FAO) for 12 years, leading the aquaculture team on environmental issues and climate change, adds her insights to our own expertise from working on small-scale aquaculture in Southeast Asia, the Middle East, and Africa for the past 20 years.

1. Implement best management practices

“Improving management practices is the first move towards climate adaptation, especially improving biosecurity, considering lower stocking densities and ensuring a good farm location,” says Soto.

Implementing best management practices (BMPs) in all aspects of production will improve the overall resilience of the farm. Susceptibility to disease is particularly likely to increase with the changing climate, as the immune system of animals is compromised when they are stressed (from for example, by warmer water in and around the farm). Ensuring fish and shrimp health through the implementation of BMPs will reduce disease risks. Environmental measures that ensure the protecting of local ecosystems will also decrease the vulnerability of farms to climate change. BMPs also contribute to improved hygiene, feed efficiency and water quality.

Guidelines on best management practices for aquaculture are provided by ASEAN, WorldFish and Sustainable Fisheries Partnership. WorldFish also published a series of videos on good aquaculture practices. Some guides are applicable to certain geographical areas or species, but much of the content can be transferred to other areas or similar species.

A man throwing a net into a shrimp pond.
Flooded shrimp ponds in the wake of Cyclone Amphan, which struck Bengal in 2020

© Gurvinder Singh

2. Perform a risk-based analysis

During site selection and farm planning for a new farm, a risk-based analysis should be performed in relation to climate change and extreme weather events. This can also be done for existing operators who want to adapt their farm. An assessment needs to examine the climate risks of an area in terms of exposure, potential impacts, and the risk mitigation capacity. The ultimate goal of a risk assessment is to come up with recommendations for measures that reduce climate-related risks: so-called adaptation measures. Based on the risk assessment, a disaster preparedness plan can be developed, with the aim to monitor risk mitigation actions such as adaptation measures.

Usually, a risk assessment is carried out by organisations covering a whole country, region or project. However, risk assessments can also be done by a group of farmers (a farmers association or cooperative) or larger individual farmers. Guidelines on how to conduct risk assessments are available from Care, UN and GIZ.

If the risk assessment finds very high risks that cannot be mitigated, relocation to safer areas should be considered. Alternatively, short-cycle aquaculture projects can be implemented in areas that face longer and regular periods of drought or flooding. For example, a fast-growing fish species can be grown which can be harvested before the rainy or dry season starts. Stocking larger fingerlings also shortens the farming period and so reduces production risks too. Finally, culturing species with the capacity to breathe air such as catfish, pangasius and climbing perch, can be a viable option where water quantity and quality is restricted. Such species can also be moved more easily in case of emergency.

3. Diversify your production

Do not put all your eggs in one basket: diversification of products is a strategy commonly used to spread risks against losses. It can enable continued production if one crop fails. When selecting species that can benefit from each other, farm diversification also reduces waste and increases productivity by using byproducts from one species as inputs for other species. It also diversifies the income sources of farmers, stabilises production and increases resource efficiency.

However, as Soto observes: “Diversification only works if different species or products are not subject to the same hazard, for example extreme events such as the one that took place in Myanmar in 2023 can impact all aquaculture farming systems and species”.

The use of integrated agriculture-aquaculture and polyculture aquaculture systems should also be considered. This approach diversifies livelihoods further, provides extra food for the family and to sell, and uses scarce water more efficiently, making it an effective climate adaptation measure. Pond water can be used for the irrigation of crops, while crop waste can be used as feed for the fish. Nutrients in the pond water from fish excretion act as a natural fertiliser for the crops. Vegetation on pond dykes also strengthens them and reduces erosion.

Selecting local strains and varieties for both the fish and crops is key, as these are in most cases best adapted to the local climate and to local pathogens.

For marine farms, integrated multi-trophic aquaculture (IMTA) can be implemented as a means to diversify. Seaweeds can be cultured around the sea cages and filter feeders such as bivalves and sea cucumbers can be grown under or around the cages. IMTA or any diversified system cannot however solve issues resulting from a common hazard, such as an extreme storm event.

Additionally, the market can be diversified between local, national, and international options. Supply to local markets has the advantage that transport requirements are limited, and it contributes to local food security.

Two women standing on a boat in front of mussel floats.
Doris Soto (right) with one of her PhD students at a mussel farm in southern Chile

© Doris Soto

4. Make use of early warning systems

Farmers should be familiar with reliable sources of information on climate change and climate variability. Timely information can enable farmers to respond quicker to climate risks. It is important to understand and interpret the meteorological predictions, such as weather forecasts, well. Make use of forecasts to prepare for extreme weather events. Daily online weather forecasts provide information on upcoming extreme weather events, like cyclones and extreme high tides. When changes in salinity, water availability and other important parameters are predicted in advance, farmers can prepare their farm to minimise losses and damage.

According to Soto, more and more farmers are already starting to use early warning systems. Most farmers now have a cell phone and early warning systems can be used with simple technology mostly coming from governments, so there is large potential for every village to be informed in case a severe cyclone is approaching, or to stay updated on the latest developments regarding an El Niño season. The main gap is understanding the forecast and improving preparedness and emergency response. Farmers can often access training through NGOs or government programmes.

Technology used in early warning systems include artificial intelligence, remote sensing and satellite imaging, and the Internet of Things. Companies such as Scoot Science and Blue Lion Labs use tools to predict outbreaks of extreme ocean events and HABs.

Examples of emergency responses to hazards include early harvesting, strengthening farm infrastructure, increasing the rate of water exchange, and the provision of aeration. Some cage farms can be towed to safer places and ropes and nets should be checked to ensure everything is tied well.

5. Farm infrastructure improvement

For inland pond farms, higher and stronger dykes can protect against flooding and provide an opportunity to have deeper ponds in preparation for droughts and hot weather, since they have a more stable water temperature and a greater dissolved oxygen reserve. They are also less sensitive to environmental factors in dry periods. Dykes should be made as stable as possible to endure floods and storms. This can be done by using the correct ratios of dyke height and width and the correct angle of the slope. Nets can be placed on dykes around ponds to prevent escapes during flooding and heavy rains.

For areas with heavy rain or floods, it is important to ensure water can flow out of the pond. For this piping and sluices for water intake and outlets are important, as well as drainage canals. Canals should be wide and deep enough to uptake extra water in case of heavy rain and floods. In case the area suffers dry periods, an inlet canal can be useful to ensure water supply from the sea or river. Water reservoirs (or spare ponds) can also be constructed to buffer for dry spells.

For marine farms, submersible sea cages can be deployed, but these are expensive and more difficult to manage, so are currently not suitable for small-scale farmers. Cage structures, mooring, and nets should be of sufficient quality to withstand the strongest storms. Farms should also have equipment to recapture escaped fish. As improving farm infrastructure is expensive, it is possible that governments, as part of their policy on climate change, provide micro-finance schemes, insurances and loans to invest in farm infrastructure. Farmers can inquire if these options are available in their respective countries.

People inspecting a fish farm.
Fish ponds with very low dykes, such as these in Zambia, are vulnerable to flooding

© Kyra Hoevenaars

6. Collaborate with other farmers

Most adaptation measures cannot be implemented by a single farmer alone. Therefore, farmer organisations and other community and government entities should play an important role in building resilient farms and communities. Farmers’ organisations allow for collective pooling of resources and skills. Other than implementing adaptation measures together (for example disease prevention), they can also work together on receiving training, exchanging information, understanding their ecosystem, infrastructure development, buying inputs and marketing of products.

A group of people meeting in the shade of some large trees.
A meeting of a fish farmers' association in Zambia

© Kyra Hoevenaars

Where do we go from here?

Despite a number of encouraging projects in this field, there are still very few detailed, data-backed success stories relating to how the adaptation measures have worked, so it is important that more studies are conducted in this area.

“At the moment, we do not have very good monitoring systems or indicators in place to measure the success of adaptation measures,” says Soto. She stresses that this is needed to select effective and feasible measures.

Additionally, the implementation of adaptation measures often comes at a considerable cost. For small-scale farmers, who work tirelessly to put food on the table in communities worldwide, while often living in poverty themselves, implementing some of these changes will thus be challenging. Government support is needed through policies, legislation and financial support for the implementation of adaptation measures. Part of this cost should also be shouldered by consumers, through higher prices.

Food security is of critical importance to our still growing global population. By working together and taking collective responsibility, aquaculture operators can help to create a climate-resilient future-proof food system.

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