Welfare impact of climate change on capture fisheries in Vietnam

a = b < 1, i.e., relative demand reduction equals supply reduction. If the decrease in demand equals the decrease in supply relative to 2018, i.e., a = b, then, from Eq (8): P1 P0 ¼ a b � � 1 εS εD ¼ 1 or P1 ¼ P0; price remains unchanged: From Eq (10): CS1 CS0 ¼ a 1 P1þεD 1 P1þεD 0 P1þεD max P1þεD 0 � � ¼ a < 1 ð18Þ From Eq (12): PS1 PS0 ¼ að1þεSÞ εS εD bð 1 εD Þ εS εD ¼ bð1þεSÞ εS εD bð 1 εDÞ εS εD ¼ b < 1 ð19Þ Eqs (18) and (19) depict that consumers and producers get losses by b relative to 2018 due to the reduction in production quantity while the price remains constant. In this case, the pro- ducer profit will likely reduce 20% to 24% by 2035 and 35% to 46% by 2065. The loss of fisher profit is from 1.0 to 1.3 billion USD (PPP, 2018) by 2035 and 2065, equal to 9%–11% of total capture value in 2018. a < b < 1, i.e., relative demand reduction is higher than supply reduction From Eq (8): P1 P0 ¼ a b � � 1 εS εD < 1 or P1 < P0; fishery price decreases: From Eq (10): CS1 CS0 ¼ a 1 P1þεD 1 P1þεD 0 P1þεD max P1þεD 0 � � � a < 1 ð20Þ From Eq (12): PS1 PS0 ¼ að1þεSÞ εS εD bð 1 εD Þ εS εD < bð1þεSÞ εS εD bð 1 εDÞ εS εD ¼ b < 1 ð21Þ Eqs (20) and (21) show that consumers and producers get losses. a > 1, i.e., demand increases From Eq (8): P1 P0 ¼ a b � � 1 εS εD > 1 or P1 > P0; fishery price increases: PLOS ONE Welfare impact of climate change on capture fisheries in Vietnam PLOS ONE | https://doi.org/10.1371/journal.pone.0264997 April 25, 2022 14 / 20