The greenhouse gas (GHG) emissions intensity from shrimp farming is about 10 kg CO2-e/kg shrimp, a value that is comparable to tropical marine finfish and about twice the average for freshwater fish. Some of the options to reduce or mitigate the GHG emissions intensity of farmed shrimp are discussed here.
Feed represents 30-40% of the emissions intensity and thus there is considerable scope to improve feed footprint. Some feed companies now consider GHG emissions and resource use and impacts in formulating feeds. Feed companies can reduce the carbon footprint of feed by using ingredients with high nutrient digestibility and nutrient bioavailability. Sub-optimal nutrient digestibility results in greater waste output. Digestible nutrient specifications should be optimized according to production environment and intensity.
Feed companies can also reduce carbon footprint of feed by avoiding large land-use change (LUC) associated with ingredient selection. Specifically this often refers to the deforestation of the Amazon and conversion of the land use into soybean fields. Such a conversion results in a large release of GHGs stored in the soil, as well as a large reduction in carbon fixation capacity. Responsible feed manufacturing would use only conversion-free soy.
There are several important things that farmers can do to minimize the carbon footprint of shrimp. Feed conversion is the main factor that affects the quantity of waste outputs, including GHGs. Using high-quality (digestible) feeds and implementing best feeding practices by feeding efficiently just below satiation can improve feed conversion. The benefit of using low carbon footprint feeds can not be realized if feed is not applied efficiently.
About 50% of the carbon footprint of shrimp is derived from on-farm energy use for water pumps and mechanical aeration. Production per unit energy varies widely among farms, with the least efficient farms being the most impactful. Greater implementation of a precision aquaculture approach to water quality management can reduce carbon footprint.
Using renewable sources of energy to support on-farm energy requirements is a questionable investment, especially for the small, intensive shrimp farms common in Asia. Relatively large areas for photovoltaic panels are needed to support intensive shrimp production. Solar panels could be a supplemental power source to grid electricity. Panels can be placed within reservoir ponds without much disruption to farm operations.
Decarbonizing electrical power grids by expanding the use of renewable and nuclear energy sources can achieve carbon footprint reductions that are larger than many of the mitigation options discussed previously. Actors outside the shrimp value chain, at high levels of government and industry, make such policy and investment decisions with potentially large benefits to GHG mitigation across the full range of economic activity.