Potential socioeconomic impacts from ocean acidification and climate change effects on Atlantic Canadian fisheries

in pH based on the mean impact findings of meta-analyses conducted in 2010 and 2013 [3,4] [31,34,37]. Potential for evolutionary responses to changing conditions are not accounted for in the current iteration of the DBEM. For additional details on the DBEM see S1 Note. Outputs from the model were structured as annual species-specific maximum catch poten- tials (a proxy for maximum sustainable yield) for cells on a global half-degree latitude by half- degree longitude grid for the period of 1950 to 2100. For each species and year combination, there were 12 datasets generated by the model representing: two Radiative Concentration Pathways (RCP) scenarios for future CO2 emissions [38,39] (RCP 2.6 –‘highly mitigated CO2 emissions’ and RCP 8.5 –‘business as usual CO2 emissions’); two OA treatments (‘with OA’; and ‘without OA’); and using three separate climate models (NOAA’s Geophysical Fluid Dynamics Laboratory (GFDL-ESM), Institute Pierre Simon Laplace Climate Modelling Centre (IPSL-ESM) and Max Planck Institute for Meteorology (MPI-ESM)) (Table 1). Data extraction for the species of interest along with the following data manipulation was performed using Mathworks MATLAB, version R2015b, and Microsoft Excel 2013. Initially, the 12 global datasets for each of the selected species were geographically constrained to include only data from grid cells corresponding to Canada’s Atlantic EEZ (NAFO areas 2, 3 and 4; Fig 2). Modifying from earlier methods, 20 year running means were calculated for

each decade (e.g., for the year 2000, values were averaged from 1991–2010) for each species’ 12 geographically truncated datasets in order to smooth interannual variability from the climate model projections [40]. This was performed for each grid cell in the truncated datasets. Median values from outputs using each of the three earth system models were used to limit the uncertainty surrounding model variability (the following steps were also performed for the datasets generated from the individual climate models, these are available in the Supporting Information S1 Table). This data manipulation resulted in a total of four datasets (two RCP scenarios and two OA treatments) for each species. The catch potentials were then summed across the DFO management areas (as per Fig 3) for each decade. Minor exceptions to this process were necessary where the median dataset projected future abundance of a given spe- cies in a management area dropping to zero. In these instances, the mean of the management area aggregated data from the three climate model values was substituted. To project future landings, DFO reported landings for the baseline period were multiplied by the relative change indicated by the outputs of the DBEM. The year 2000 was used as the reference year against which future changes in potential landings were assessed. Relative Table 1. Schematic representation of data configuration for each species, s. Each of the 12 configurations yielded a separate global distribution of catch potential in half-degree latitude by half-degree longitude cells for each year, Y that

was modelled (1950–2100). Species s, Year Y RCP 2.6 with OA GFDL-ESM IPSL-ESM MPI-ESM without OA GFDL-ESM IPSL-ESM MPI-ESM RCP 8.5 with OA GFDL-ESM IPSL-ESM MPI-ESM without OA GFDL-ESM IPSL-ESM MPI-ESM https://doi.org/10.1371/journal.pone.0226544.t001 OA and climate change impacts on Atlantic Canadian fisheries PLOS ONE | https://doi.org/10.1371/journal.pone.0226544 January 10, 2020 5 / 29