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

management area. From here forward, the term ‘quartet’ will be used to refer to the four expo- sure scenarios, as well as the subsequent potential impact scores. EA;Y;r ¼ X DA;Y;r;s � VA;s VA;tot ! " # S Eq 2 Where EA,Y,r is the exposure indicator score for area A, in time-step Y, and RCP scenario r. ΔA, Y,s is the DBEM predicted relative change in landings for time-step Y, RCP scenarios r, and species s (from Eq 1). VA,s is the year 2000 average annual value for species s, and VA,tot is the total annual landings of the seven species value for the management area (Table 2). The impact index was constructed so that high scores implied higher potential for impact. To align the exposure scores with this orientation, the values were multiplied by (-1) so that losses in potential future landings became positive. Additionally, in order to combine the sepa- rate index indicators, it was necessary to first normalise each separate indicator to score between 0 and 1 [42,43]. Therefore, the 12 exposure values (three management areas, each with a quartet of scores) were normalised following a min-max calculation to score between 0 and 1 (Eq 3) [43]. Min-max normalization is a widely used method to allow distinct indicators with different units to have the same range of values (i.e., 0–1) for more straightforward inte- gration into an index [43]. In the index, the exposure indicator scores for management areas Fig 4. Framework for the impact index demonstrating relationship between components. Elements at each branch

are equally weighted to other items at the same level as indicated by bracketed numbers. https://doi.org/10.1371/journal.pone.0226544.g004 Table 2. Cumulative exposure indicator of future changes in fisheries (before normalisation of values). Values in fourth and fifth columns are the indicator scores (i.e., the relative change in landings scaled by proportional value of the individual species). For integration into the impact index, the exposure scores were reversed and then normalised to score between 0 and 1, so that declines in landings earned a high score and implied a high exposure to OA and climate change. Management region Exposed provinces Climate scenario Exposure indicator scores 2050 2090 Maritime NS-mar; NB-mar RCP 2.6 -0.114 -0.166 RCP 8.5 -0.202 -0.498 Gulf NS-gulf; NB-gulf; PEI; Que RCP 2.6 0.042 0.017 RCP 8.5 0.070 0.033 Newfoundland and Labrador NL RCP 2.6 -0.012 -0.026 RCP 8.5 0.015 0.060 Regional total n/a RCP 2.6 -0.014 -0.034 RCP 8.5 -0.018 -0.069 https://doi.org/10.1371/journal.pone.0226544.t002 OA and climate change impacts on Atlantic Canadian fisheries PLOS ONE | https://doi.org/10.1371/journal.pone.0226544 January 10, 2020 8 / 29