Uncertainty in future projections of global and regional marine fisheries catches

William W.L. Cheung1, Thomas L Froelicher2, Charles A Stock3, Miranda C Jones4, Gabriel Reygondeau1 and Jorge L Sarmiento5, (1)The University of British Columbia, Institute for the Oceans and Fisheries, Vancouver, BC, Canada, (2)Universtity of Bern, Climate and Environmental Physics, Bern, Switzerland, (3)Geophysical Fluid Dynamics Laboratory, Princeton, NJ, United States, (4)University of Cambridge, United Kingdom, (5)Princeton University, Program in Atmospheric and Oceanic Sciences, Princeton, NJ, United States
Previous studies have projected the global redistribution of potential marine fisheries catches by mid-21st century under climate change, with increases in high latitude regions and pronounced decreases in tropical biomes. However, quantified confidence levels of such projections are not available, rendering it difficult to interpret the associated risk to society. This paper quantifies the confidence of changes in future fish production using a 30-member ensemble simulation of the Geophysical Fluid Dynamics Laboratory ESM2M (representing internal variability of oceanographic conditions), three structural variants of a mechanistic species distribution model (representing uncertainty in fisheries models and different greenhouse gas emission and fishing scenarios (representing scenario uncertainty).

We project that total potential catches of 500 exploited fish and invertebrate stocks, that contribute most to regional fisheries catches and their variability, will likely decrease in the 21st century under a ‘business-as-usual’ greenhouse gas emission scenario (RCP8.5). Fishing and it’s management remains a main factor determining future fish stocks and their catches. Internal variability of projected ocean conditions, including temperature, oxygen level, pH, net primary production and sea ice contributes substantially to the uncertainty of potential catch projections. Regionally, climate-driven decreases in potential catches in tropical oceans and increases in the Arctic polar regions are projected with higher confidence than other regions, while the direction of changes in most mid-latitude (or temperate) regions is uncertain. Under a stringent greenhouse gas mitigation scenario (RCP 2.6), climate change impacts on potential catches may not emerge from their uncertainties. Overall, this study provides a foundation for quantifying risks of climate change impacts on marine fisheries globally and regionally, and how such risk may be altered by policy interventions.