Climate threats to catfish raising in Viet Nam: A CCAFS report
The main climate risks to catfish production in the Mekong Delta are: (i) sea level rise and the consequent detrimental impacts of saltwater intrusion and heightened flood risk; (ii) changes in rainfall patterns and therefore river flow, which are expected to result in an increase in flooding and drought, as well as the potential for decreased in freshwater availability in some areas; (iii) rising temperatures which may alter breeding and growing rates among fish, and increase organic decomposition and eutrophication, leading to higher costs for aeration machinery.
The key adaptation measures for managing the foreseen impacts of climate change within the region comprise: (i) infrastructural measures, including dyke heightening/reinforcement, improved water storage and water management; (ii) practice and technology, including the relocation of production, modified stocking cycles/rates and development of salt-tolerant species.
CCAFS validates the IFAD statements below. One caveat is the statement "Projections of climate-related changes in the mean annual flow in the Mekong River range from a decrease of 5% to 20%." In fact, the annual flow in the Mekong River is anticipated to increase, not decrease. The IFAD statement may have originated in a misinterpretation of a sentence in one of the key working papers on the Mekong, produced by WorldFish under the CCAFS research program on page 11 it states: 'Projections of climate-related changes in mean annual flow in the Mekong River range from 5% (Hoanh et al. 2003) to 20% (Eastham et al. 2008)'. Checking the original scientific journal article references shows that they are referring to an increase in river flow. So it seems that the statement used in IFAD's second bullet point (i.e. a decrease) is in fact the opposite of what was meant in the original reference. Nonetheless, changes in the hydrological regime, and the resulting over/under supply of water through the season, may impact negatively upon on catfish production. Notably, increasing variability in water flow (i.e. higher peak flows and lower minimum flows) is likely under climate change and thus the message of that bullet point, that there are risks to the water level in catfish ponds, is valid.
Climate risks to catfish
- Changes in sea level in the Mekong Delta causes salt water intrusion and increases the chances of floods. Both are not benefiting fish farming.
- Aquaculture ponds are dependent on freshwater supplies from rivers and canals, rather than rainfall. Projections of climate-related changes in the mean annual flow in the Mekong River range from a decrease of 5% to 20%. This would endanger the water level of the ponds the catfish live in.
- The increased water salinity, plus higher evaporation rates from ponds due to higher temperatures, would also increase pumping of freshwater into the ponds, hence incurring additional electricity and fuel costs in operating the aquaculture farms
- Investing in more climate smart agriculture, taking into account increased salinity for fish farming.
- Research on saline tolerant catfish varieties
- Small infrastructure to limit saltwater intrusion in aquaculture ponds
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