By Watmore Makokoba
Fish farming is a lucrative enterprise upon which millions of people and economies rely on in Sub Saharan Africa, however the viability of this venture faces threats due to climate change.
The lowering of water levels in the world’s largest man-made water body, Lake Kariba which is shared by Zimbabwe and Zambia, experienced in the past few years, save for last year, affected breeding processes and fish populations, negatively affecting the communities relying solely on the fish industry.
According to Food and Agriculture Organisation of the United Nations (FAO), urgent adaptation measures are required in response to opportunities and threats to food and livelihood provision due to climatic variations.
“There is evidence that global warming is changing the thermal regimes of tropical lakes, between 1986 and 2011 the mean temperature of the lake rose by 0.7 °C, a rate equivalent to 0.03 °C y−1, these changes appear to have disrupted the thermal regime which now seems to be less predictable than before” FAO says.
The same report suggests that warming in Lake Kariba due to climate change has strengthened stratification and has caused the thermocline to rise, reducing the productivity of the fisheries.
“Climate change is a compounding threat to the sustainability of capture fisheries and aquaculture development. Impacts occur as a result of both gradual warming and associated physical changes as well as from frequency, intensity and location of extreme events, and take place in the context of other global socio-economic pressures on natural resources” reads the report.
Research Gate, an aquifer research institute posits that in communities like Kariba which largely depend on fisheries for sustaining livelihoods, climate change disrupts the whole system retarding community development.
“Inland fisheries are important for nutrition, employment, and income, but climate variability and change are adding to other stressors, such as overexploitation, pollution, habitat degradation, and invasive species, to threaten their productivity as well as livelihoods of fisheries-dependent communities. Understanding the whole socio-ecological system to enable communities to adapt and build resilience is therefore vital, ” reports Research Gate.
The World Bank in a report released in November last year submitted that the current trend is that rainfall has been decreasing at a rate of 0,63 millimeters per annum in the region that the lake occupies and that evaporation rates also rose by an estimated 31 percent partly explaining evidence of decline water levels in the lake
“Research has even raised the possibility of fish supply significantly declining over the next decades, because of the combination of climate change and the hydropower network,” World Bank reported.
This prompts an urgent need for ways to reduce the impact of climate change on fisheries, which calls for timeous formulation and implementation of sustainable mitigation initiatives to serve the threatened industry.
Awakening to this situation, Panos Institute of Southern Africa based in Zambia came up with an initiative to mitigate fish depletion by strengthening fish farming as a means to restore fish populations within Lake Kariba community.
“Realizing the far-reaching threats presented by fish depletion in water bodies such as lakes and rivers, Panos Institute Southern Africa has supported the community members along the Zambezi Valley to adopt fish farming as one of the solutions.”
Panos is working with the local fisheries departments and experts to support the communities to adopt fish farming to meet the demand for fish for local consumption and for sale.
“The success of fish farming will make a big difference in these two districts where livelihoods for the majority of community members revolve around fishing. This will also reduce the pressure on Lake Kariba and the Zambezi River which have experienced significant declines in capture fish outputs”, said Lilian Saka Kiefer Executive Director, Panos Institute Southern Africa (PSAf)