Course 4: Increase Fish Supply (Synthesis)

  • Improve Wild Fisheries Management
  • Improve Productivity and Environmental Performance of Aquaculture
Course 4
Increase Fish Supply (Synthesis)

Fish, including finfish and shellfish, provide only small percentages of total global calories and protein, but they contribute 17 percent of animal-based protein,69 and are particularly important for more than 3 billion people in developing countries.70 We project fish consumption to rise 58 percent between 2010 and 2050, but the wild fish catch peaked at 94 million tons in the mid-1990s and has since stagnated or perhaps declined.71 This course proposes ways to improve wild fisheries management and raise the productivity and environmental performance of aquaculture.

  • Improve Wild Fisheries Management

    According to FAO, 33 percent of marine stocks were overfished in 2015, with another 60 percent fished at maximum sustainable levels (Figure 15). One World Bank study found that world fishing effort needs to decline by 5 percent per year over a 10-year period just to allow fish stocks to rebuild.72

    Solutions to curb overfishing are well-known and documented. They focus on principles including limiting catches to a level that allows the fish population to reproduce, limiting the number of fishers to an economically sustainable level, protecting habitat, and avoiding harvest during important breeding times or in important breeding areas.

    The challenges to implementing these solutions are largely political and social. Wild fish are a public resource that individual fishers have incentives to exploit before others can do so. Other challenges reflect power imbalances, where foreign fleets from richer countries often are able to obtain agreements to fish in the waters of poorer countries with weaker laws and enforcement capacity. Solutions require mechanisms for persuading fishers to support reductions in fish catch levels:

    • Catch shares limit total fish catch and allocate shares of the catch among fishers, who then have a long-term interest in preserving the health of the fishery.
    • Where oversight is weaker, community-based comanagement systems may prove more effective. Such systems combine territorial fishing rights and no-take reserves designed and supported by coastal fishing communities.
    • Removing perverse subsidies—estimated at $35 billion annually73—could dramatically reduce overfishing.

    Because reducing overfishing is hard, we assume a 10 percent reduction in wild fish catch between 2010 and 2050 in our baseline scenario, and even that goal requires major reforms. A scenario in which fisheries are rebuilt enough to maintain the 2010 level of fish catch in 2050 would have little effect on our gaps but would supply an additional 9 Mt of fish (relative to our 2050 baseline) and would avoid the need to convert 5 Mha of land to supply the equivalent amount of fish from aquaculture ponds.

    Figure 15 |

    The percentage of overfished stocks has risen over the past 40 years

    The percentage of overfished stocks has risen over the past 40 years

    Source

    FAO (2018).

  • Improve Productivity and Environmental Performance of Aquaculture

    Growth in world fish supply since the 1990s has come from aquaculture (fish farming). Aquaculture production would need to more than double between 2010 and 2050 to meet projected fish demand in our baseline (Figure 16).

    Aquaculture is a relatively efficient means of supplying animal-based protein. Although efficiencies vary by type of fish and production method, average land-use demands are on par with poultry production (Figure 5) and can even be zero for certain species (e.g., bivalve mollusks). Greenhouse gas emissions from aquaculture are similar to those of poultry and pork production, and much less than those of ruminant meats.

    Yet aquaculture presents a range of environmental challenges, which vary by production system. They include conversion of valuable wetland habitats (such as mangroves), use of wild-caught fish in feeds, high freshwater demand, water pollution, and effects of escaped farm fish on wild fish. Aquaculture ponds occupied an estimated 19 Mha in 2010, while an additional 27 Mha was used to grow crop-based fish feed. The total land-use demands roughly double in our 2050 baseline projection.

    Aquaculture must become more land-efficient, especially because available land is constrained in Asia, where nearly 90 percent of aquaculture production occurs.74 Shifting to deeper ponds with water recirculation will be necessary to increase production while limiting land expansion. Opportunities also exist to expand aquaculture in marine waters, possibly further offshore.

    Aquaculture growth will require development of feed substitutes to replace oil from wild fish because this source is already near or above ecological limits. Promising alternatives include microalgae-based feeds and uses of genetically engineered yeasts or oilseeds bred to produce the omega-3 fatty acids that characterize wild fish oil. Aquaculture must also overcome significant rates of fish disease.

    Several strategies can help aquaculture grow sustainably to help meet rising fish demand:

    • Selective breeding for improved fish growth rates and conversion efficiencies.
    • Technological developments in fish oil alternatives, other feed improvements, and disease control.
    • Use of water recirculation and other pollution controls.
    • Use of spatial planning to optimize aquaculture siting.
    • Expansion of marine-based systems.

    Figure 16 |

    Aquaculture production must continue to grow to meet world fish demand

    Aquaculture production must continue to grow to meet world fish demand

    Source

    Historical data, 1950–2016: FAO (2017b) and FAO (2018). Projections to 2050: Calculated at WRI; assumes 10 percent reduction in wild fish catch from 2010 levels by 2050, linear growth of aquaculture production of 2 Mt per year between 2010 and 2050.

Course 5: Reduce Greenhouse Gas Emissions from Agricultural Production (Synthesis)

Course 5
Reduce Greenhouse Gas Emissions from Agricultural Production (Synthesis)
Agricultural production emissions arise from livestock farming, application of nitrogen fertilizers, rice cultivation, and energy use. These production processes are traditionally regarded as hard to control. In general, our estimates of mitigation potential in this course are more optimistic than others’, partly because many analyses have not fully captured the opportunities for productivity gains and partly because we factor in promising potential for technological innovations.
Endnotes
  • 69
    FAO (2017a).
  • 70
    In 2013–15, fish provided about 3.2 billion people with 20% of their animal protein intake (FAO 2018).
  • 71
    FAO (2017b).
  • 72
    World Bank (2017b).
  • 73
    Sumaila et al. (2010); Sumaila et al. (2012); Sumaila and Rachid (2016).
  • 74
    FAO (2017b).
  • Improve Wild Fisheries Management
  • Improve Productivity and Environmental Performance of Aquaculture
Endnotes

Course 5: Reduce Greenhouse Gas Emissions from Agricultural Production (Synthesis)

Course 5
Reduce Greenhouse Gas Emissions from Agricultural Production (Synthesis)
Agricultural production emissions arise from livestock farming, application of nitrogen fertilizers, rice cultivation, and energy use. These production processes are traditionally regarded as hard to control. In general, our estimates of mitigation potential in this course are more optimistic than others’, partly because many analyses have not fully captured the opportunities for productivity gains and partly because we factor in promising potential for technological innovations.
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