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Expanding ocean food production under climate change

Abstract

As the human population and demand for food grow1, the ocean will be called on to provide increasing amounts of seafood. Although fisheries reforms and advances in offshore aquaculture (hereafter ‘mariculture’) could increase production2, the true future of seafood depends on human responses to climate change3. Here we investigated whether coordinated reforms in fisheries and mariculture could increase seafood production per capita under climate change. We find that climate-adaptive fisheries reforms will be necessary but insufficient to maintain global seafood production per capita, even with aggressive reductions in greenhouse-gas emissions. However, the potential for sustainable mariculture to increase seafood per capita is vast and could increase seafood production per capita under all but the most severe emissions scenario. These increases are contingent on fisheries reforms, continued advances in feed technology and the establishment of effective mariculture governance and best practices. Furthermore, dramatically curbing emissions is essential for reducing inequities, increasing reform efficacy and mitigating risks unaccounted for in our analysis. Although climate change will challenge the ocean’s ability to meet growing food demands, the ocean could produce more food than it does currently through swift and ambitious action to reduce emissions, reform capture fisheries and expand sustainable mariculture operations.

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Fig. 1: Impact of climate change and fisheries management on the production of seafood from marine fisheries.
Fig. 2: Opportunities for the expansion of sustainable mariculture to increase seafood production under climate change.
Fig. 3: Global seafood production per capita from marine fisheries and mariculture.
Fig. 4: National seafood production trends and mariculture production footprints under different mariculture-development scenarios.

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Data availability

The data that support this study are available on GitHub (https://github.com/cfree14/aquacast).

Code availability

The codes that support this study are available on GitHub (https://github.com/cfree14/aquacast).

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Acknowledgements

We thank Z. Song for sharing the wave-height data. This research is adapted from a Blue Paper commissioned by the High Level Panel for a Sustainable Ocean Economy entitled ‘The Expected Impacts of Climate Change on the Ocean Economy’. This research was funded by the High Level Panel for a Sustainable Ocean Economy, Food and Land Use Coalition, and Environmental Defense Fund. E.O. was funded by the European Research Council project CLOCK (GA. 679812) and GAIN-Xunta de Galicia Oportunius programme. The results, conclusions and opinions expressed are those of the authors and do not necessarily reflect the views of their respective organizations.

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Authors

Contributions

S.D.G., C.M.F., R.B.C., K.F. and C.T. conceived the study. C.M.F., R.B.C., S.D.G., E.O., H.E.F., K.F. and C.T. contributed to the study design. C.M.F., R.B.C., J.E.P., H.E.F., J.G.M., K.J.S., S.D.G., W.B., K.F., M.A.J.-M. and R.A. contributed to the acquisition and analysis of data. C.M.F., R.B.C., S.D.G., W.B., E.O., E.O’R., J.E.P., H.E.F., J.G.M., K.J.S., K.F., C.T., M.A.J.-M. and R.A. contributed to the interpretation of results. C.M.F., R.B.C., S.D.G., W.B., E.O., E.O’R., J.E.P., H.E.F., J.G.M., K.J.S., K.F., C.T., M.A.J.-M. and R.A. wrote and edited the manuscript.

Corresponding author

Correspondence to Christopher M. Free.

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Competing interests

S.D.G. is a trustee of the National Marine Sanctuary Foundation, Rare, Resources Legacy Fund and COMPASS. H.E.F. sits on the Technical Advisory Group for the Aquaculture Stewardship Council. All other authors declare no competing interests.

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Nature thanks Kevern Cochrane, Simon Donner, Elizabeth Fulton, Alex Sen Gupta, U. Rashid Sumaila and the other, anonymous, reviewer(s) for their contribution to the peer review of this work. Peer reviewer reports are available.

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Extended data figures and tables

Extended Data Fig. 1 Opportunities for the expansion of sustainable mariculture to increase seafood production under climate change in the price and cost sensitivity analysis.

In this analysis, mariculture seafood prices are 30% lower and mariculture operation costs are 30% higher than in our base scenario. The top row (a–d) illustrates the technological progress already made towards fostering future mariculture expansion48. In (d), the FIFO (“fish in, fish out”) ratio represents the amount of wild fish required to produce one unit of farmed fish; ratios below one (the dashed horizontal line) indicate the efficient conversion of wild fish into farmed fish23,24,41. Points represent historical values and lines represent projected exponential declines. The bottom row shows the (e) amount of potentially profitable area available for mariculture and the (f) annual production potential of this profitable area under climate change. In (f), bars represent the environmental and economic potential for sustainable mariculture if unconstrained by the upper limits of future consumer demand (dotted lines) or the availability of feed from capture fisheries (points). The upper limits of future consumer demand were estimated to be double the 2050 demand estimated by Costello et al14. Note the log-scale y-axis in (f).

Extended Data Fig. 2 Global seafood production per capita from marine fisheries and mariculture under climate change in the price and cost sensitivity analysis.

In this analysis, mariculture seafood prices are 30% lower and mariculture operation costs are 30% higher than in our base scenario. Panels show (a) historical production per capita48,49 and potential future production per capita under climate change and (b) business-as-usual (BAU) or (c) progressive reforms in fisheries and mariculture policies. In (b) and (c), dashed lines indicate current seafood production per capita. BAU fisheries management assumes that current harvest rates degrade as populations shift into new management areas whereas reformed fisheries management assumes that economically optimal harvest rates are maintained as populations shift into new management areas. BAU finfish mariculture policies assume moderate advances in “fish in, fish out” (FIFO) ratios (values projected for 2030; see Fig. 3) while reformed finfish mariculture policies assume substantial advances in FIFO ratios (values projected for 2050; see Fig. 3). Bivalve mariculture is the same in both policy scenarios.

Extended Data Fig. 3 National seafood production trends and mariculture production footprints under different mariculture development scenarios in the price and cost sensitivity analysis.

In this analysis, mariculture seafood prices are 30% lower and mariculture operation costs are 30% higher than in our base scenario. The top row shows the (a) percent of coastal countries (n = 164 countries) with increasing seafood production per capita from 2017 to 2091–2100 with progressive reforms in marine fisheries and mariculture under climate change and mariculture development scenarios. The bottom row shows (b) the percent of Exclusive Economic Zones (EEZs) (n = 164 countries) that would be developed for mariculture in 2091–2100 under each climate change and mariculture development scenario. Boxplots show the distribution of development percentages among countries and points show the percent of EEZs developed globally. High percentages occur in countries with very small EEZs (e.g., Belgium). In the boxplots, the solid line indicates the median, the box indicates the interquartile range (IQR; 25th and 75th percentiles), the whiskers indicate 1.5 times the IQR, and the points beyond the whiskers indicate outliers. Note the log-scale y-axis. The current development scenario assumes that country’s develop mariculture in proportion to today’s production; the proportional development scenario assumes that country’s develop mariculture in proportion to projected 2100 population size; the offset-based development scenario assumes that only countries losing seafood per capita from fisheries develop mariculture; and the optimum development scenario assumes that mariculture development is optimized to maintain seafood production per capita for the maximum number of countries.

Extended Data Fig. 4 Seafood production per capita in the business-as-usual management scenario under climate change and alternative human population size trajectories.

The main text results feature the 50th percentile population size projections shown in Supplementary Fig. 1.

Extended Data Fig. 5 Seafood production per capita in the progressive reforms management scenario under climate change and alternative human population size trajectories.

The main text results feature the 50th percentile population size projections shown in Supplementary Fig. 1.

Supplementary information

Supplementary Information

This file contains the Supplementary Methods, Supplementary Tables 1–18, Supplementary Figs. 1–22, Supplementary equations (1)–(6) and Supplementary References.

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Mariculture species database.

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Free, C.M., Cabral, R.B., Froehlich, H.E. et al. Expanding ocean food production under climate change. Nature 605, 490–496 (2022). https://doi.org/10.1038/s41586-022-04674-5

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