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

were treated as having equal weights. The three adaptive capacity indicators (for employment, education and aquaculture production) were averaged to obtain a cumulative adaptive capac- ity score with a maximum potential value of 1 Eq 6. ACP ¼ ðUENP þ EdNP þ AqNPÞ 2 Eq 6 Where AC is the adaptive capacity score for province P, and UENP is the normalised provincial unemployment indicator, EdNP is the normalised education level indicator and AqNP is the normalised aquaculture indicator. Vulnerability: Sensitivity and adaptive capacity were treated as having equal weights, and their values were averaged to arrive at a social vulnerability score for each province, with a potential maximum value of 1 (Fig 4). Weighting the sensitivity and adaptive capacity compo- nents equal to each other indirectly applied different weights to their composite indicators (Fig 4). However, the concepts of sensitivity and adaptive capacity represent different aspects of social vulnerability so their overall contributions were treated as equally relevant regardless of the number of indicators. Vulnp ¼ ðSenP þ ACPÞ 2 Eq 7 Where VulnP is the vulnerability score, SenP is sensitivity (Eq 4) and ACP is adaptive capacity (Eq 6) for province P. Potential socioeconomic impact. To calculate the final impact index scores the exposure and vulnerability scores were equally weighted and then combined. Each province (or sub-sec- tion thereof for NB and NS) received a quartet of potential impact scores following the quartet

of exposure indicator scores that were applied. The 28 final index scores were divided into five categories of potential impact, and described as ‘high,’ ‘moderate,’ ‘low,’ ‘minimal’ and ‘least’ potential for impact from OA and climate change. Each category represented six separate index scores, except the middle category (low), which only included four scores. Categories were not interpreted as absolute descriptors of the risk posed to the provinces, rather they describe relative levels of potential for impact within the Atlantic Canadian region. PP ¼ ðIP þ VulnPÞ 2 Eq 8 Where P is the potential impact index score, I is the normalised exposure score (Eq 3) and Vuln is the vulnerability score (Eq 7) for province P. Results Species Shellfish make up nearly half of the total annual landing weight in Atlantic Canada. Further- more, shellfish species typically receive a higher value per tonne than finfish, such that shellfish landings make up nearly three quarters of the total annual fisheries value (Fig 1 and S3 Table). Within shellfish landings, crustacean species are dominant, with northern shrimp (Pandalus borealis), snow crab (Chionoecetes opilio) and American lobster (Homarus americanus) accounting for over 60% of the total shellfish landed weight (30%, 21%, and 12% by weight respectively; and 17%, 26% and 41% by landings value, Fig 5). Nonetheless, some mollusc spe- cies also contribute substantially to landings, with sea scallop (Placopecten magellanicus), Stimpson’s surf clam (Mactromeris polynyma), eastern blue mussel (Mytilus edulis) and Ameri-

can oyster (Crassostrea virginica) representing 19%, 7%, 5%, and 3% of all shellfish landings by OA and climate change impacts on Atlantic Canadian fisheries PLOS ONE | https://doi.org/10.1371/journal.pone.0226544 January 10, 2020 12 / 29