fishing effort expended, this increase in efficiency could reduce GHG emissions by a total of 0.081 GtCO2e/year, or to roughly half the current fishing emissions, and 0.137 GtCO2e/year in 2050.
Reducing emissions from aquaculture
Dr Thierry Chopin Reducing the carbon footprint of oceanderived food production (fisheries and aquaculture) and shifting diets: Another of the five opportunities to make the ocean part of the solution to climate change
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n my October 2019 column, I reported that we (19 researchers and policy analysts) published the report “The Ocean as a Solution to Climate Change: Five Opportunities for Action” for the High Level Panel for a Sustainable Ocean Economy (HLPSOE). Our publication was endorsed by the panel’s 14 serving heads of state and government members at the United Nations Secretary-General’s Climate Action Summit in New York, on September 23rd, 2019. We believe that, through five opportunities for action, the ocean could be a substantial solution to climate change. It could deliver up to 21 percent (11.82 GtCO2e/year) of the annual greenhouse gas (GHG) emissions cuts needed by 2050 to keep global temperature rises below 1.5°C. In my November 2019 column, I developed one of the opportunities for action that should be of interest to the readers of International Aquafeed and the aquaculture sector: investing in nature-based actions and seaweed farming. In this column, I will look at the potential mitigation impact of reducing the carbon footprint of ocean-derived food production (wild capture fisheries and aquaculture) and the potential reductions from shifting diets to include more low-carbon sources of ocean-based proteins, if those seafood options can be provided on a sustainable basis.
Reducing emissions from wild capture fisheries
Different types of food, harvested and produced in different places by different means, can vary by more than an order of magnitude in the total GHGs they emit across their full life cycle. It is estimated that global wild capture fisheries account for roughly four percent of global food system production emissions. Reductions in emissions from wild-capture fisheries can be achieved in ways ranging from technological advances in engine efficiency or hull design to changes in skipper behaviour, such as speed reductions and willingness to fish in poor conditions. However, while technological changes, such as gear design and engine retrofits, have been demonstrated to influence fuel-use rates in individual vessels, the effects of such changes at the fleet level are unclear and can be overshadowed by variation in stock abundances or structural changes to the fisheries. A more consistently reliable driver of emissions within a fishery is catch per unit effort, reflecting both effort (e.g. days fished) and available biomass. If wild fish catch could increase by 13 percent by 2030, with significantly less
Global analyses of the complete GHG footprint of aquaculture are lacking, and many systems that make up a large portion of global production have not been sufficiently assessed. However, some clear patterns have emerged from the literature available to date. In particular, the largest source of emissions from finfish and crustacean aquaculture is commonly the feed provided. Minimising the carbon profile of aquaculture feeds could, therefore, represent a source of future emission reductions, or at least avoid emissions increases. The composition of fish feeds varies greatly, especially between herbivorous, omnivorous, and carnivorous species. Two of the key components of many feeds for omnivorous and carnivorous species have historically been fish meal and fish oils, which are products derived primarily from forage fish fisheries and increasingly from trimmings of other species during processing. There are active debates concerning the logic behind feeding wild fish to farmed fish rather than using the wild fish for direct human consumption. In addition, the global supply of fish meal is now at a historical high and may be near biological limits. As a result, the continued growth of fed aquaculture has driven dramatic increases in the price of fish meal and incentivized reductions in the fish meal and fish oil content of many aquaculture feeds. To date, the primary replacements for fish meal have been soy and other agricultural crops, which often create high GHG emissions. More recent substitutes for fish meals and oils include a range of livestock-derived inputs (e.g. blood, meat, and feather meal), which typically have even higher levels of GHG emissions. Many of these substitutes, and particularly those derived from some crops, can have trade-offs in terms of fish and crustacean growth and health, especially for farmed predators. Consequently, efforts are now being made to identify new, highly nutritious, and ideally, low-impact feed sources. Some of the most promising options are a variety of protein concentrates derived from a range of single cell organisms including yeast, bacteria, or microalgae. Although the motivation for this innovation was to provide better quality feeds, one of the fortunate benefits is that some of these alternative feed inputs have significantly lower GHG emission intensities than soy-based proteins. Other emerging feed alternatives, such as insects, need to be analysed regarding their GHG emissions and benefit trade-offs. Given current projections for aquaculture growth, it can be estimated that targeting new low-emission alternatives as replacement feed components, rather than soy-based proteins or other high-GHG sources, could avoid annual emissions from the industry of 0.043 GtCO2e/year by 2050. If the pace of aquaculture growth increases further because of projected growth in demand, these emission savings could increase by more than one third. Since many options are emerging to replace the fish meal fraction in feeds, realising potential emissions co-benefits will require incentives. For example, a well-structured price on carbon, detailed full life-cycle assessments of emissions from new feeds, targeted investments, information, and certification campaigns would help prioritise low-emission feed options.
Reducing emissions by shifting diets to ocean-based proteins
Food will play an increasingly large role in future climate change mitigation efforts. GHG emissions from food systems are high, particularly from livestock production, and demand
12 | January 2020 - International Aquafeed