Aquaculture and fisheries play a crucial role in Bangladesh, supplying 60% of the country’s dietary animal protein. Over the past thirty years, the contribution of this sector to the overall fish supply has grown significantly. As the sector continues to expand, it is important to recognise the greenhouse gas (GHG) emissions associated with it. GHG contains mainly carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O). Identifying ways to reduce these emissions is essential for supporting the sustainable growth of aquaculture and fisheries.
In Bangladesh, the aquaculture and fisheries sector primarily depends on large ponds, haors (wetlands) and rivers. Fingerlings are mostly sourced from hatcheries located throughout the country. For aquaculture, fish feed is a crucial input. The production processes for fish feed including grinding, mixing, drying, transporting etc. consume energy, which results in GHG emissions. The use of manure and inorganic fertilisers to boost aquaculture production also contributes to CO2, CH4, and N2O emissions.
Additionally, fuel usage from small to medium-sized fishing vessels, which typically operate on diesel, kerosene, or petrol, is another significant source of GHG emissions. Aquaculture is the largest contributor to greenhouse gas emissions, accounting for 96% of total GHG emissions from the fisheries sector. The primary component of these emissions is methane (CH4), which contributes 2.55 Mt CO2e, while nitrous oxide (N2O) plays a minor role.
Traditional and improved pond cultivation methods contribute significantly to these emissions, with poor water quality and inadequate feed management exacerbating the problem. Pond aquaculture alone accounts for 1.96 Mt CO2e, followed by shrimp or prawn farming at 0.99 Mt CO2e, and seasonal cultured water bodies at 0.52 Mt CO2e. Emissions from crab culture, pen culture, baor fisheries and cage culture are relatively small.
A study also found that coastal and marine capture fisheries are the second major source of greenhouse gas emissions, followed by inland capture fisheries and emissions related to fish marketing and transportation (Islam et al., 2020). The study forecasts total GHG emissions from the Bangladeshi aquaculture sector under three different growth rate scenarios. The current growth rate is 6.37%, but intensified production may lead to higher rates in future.
Focusing on aquaculture can help achieve the dual goals of reducing greenhouse gas emissions and increasing the supply of affordable protein. Various studies suggest mitigation measures to lower emissions in the fisheries sector. These include reducing the emission intensity of feed materials and feed mills, improving feed management, enhancing the food conversion ratio, and minimising nitrous oxide (emissions from ponds. Innovations like aquaponics and biofloc technology can improve aquaculture systems while requiring less energy through semi-aeration and intermittent aeration.
Incorporating seaweed or macrophytes into biofloc-based integrated aquaculture systems can help capture excess CO2, further decreasing GHG emissions. Additionally, recirculating aquaculture systems are eco-friendly alternatives that significantly reduce GHG emissions compared to open net-cage cultures. To decrease the use of carbon-based fuels, industrial fishing vessels should work to improve fuel efficiency, while small-scale fishers can reduce fuel consumption by enhancing engine efficiency or utilising sails. Harnessing solar energy on fishing boats could also save costs and lower GHG emissions from the fisheries sector.
As we have already mentioned, aquaculture and fisheries are critical sectors for Bangladesh, providing essential dietary protein and supporting the livelihoods of millions. However, the significant GHG emissions associated with these industries pose substantial risks that should not be overlooked.The socio-economic implications of these emissions also require serious consideration. Communities that depend on fisheries and aquaculture are vulnerable to climate change impacts, necessitating a proactive approach to sustainability. By prioritising emission reduction, Bangladesh can simultaneously improve food security and contribute to global efforts to combat climate change.The International Fund for Agricultural Development (IFAD) has played a key role in implementing projects aimed at improving fisheries and aquaculture production. These projects have focused on increasing incomes for impoverished communities and strengthening local organisations. As a result, access to water bodies has improved, and sustainable services have been established.
These initiatives have empowered rural communities by enhancing resources, reintroducing community-owned land, and enabling fishers to manage waterways effectively. Furthermore, IFAD’s efforts are in line with Bangladesh’s Nationally Determined Contributions, promoting climate-smart practices in aquaculture and resource management.
Advancing the sustainable development of aquaculture and fisheries in Bangladesh requires a balanced approach that emphasises environmental stewardship alongside economic viability. By implementing effective mitigation measures and fostering innovation, the country can work towards a future where aquaculture and fisheries thrive while minimising its carbon footprint and ensuring the resilience of its aquatic ecosystems.
