Welfare impact of climate change on capture fisheries in Vietnam

As shown in Table 3, the temperature will rise in both RCPs. 4.5 and 8.5, from 1.4 to 1.9˚C by mid-century (2046-2065) and from 1.8 to 3.4˚C by the end of the century (2080-2099). Rainfall may increase or decrease in different areas in different scenarios, but precipitation will average from 15% to 17% by mid-century and 17% to 21% by end-century. The typhoon inten- sity is likely to increase from 2% to 11% [77]. Fig 2 illustrates the potential decrease in catch yield compared to 2018, based on the RCPs 4.5 and 8.5. Fig 2 shows that temperature rise accounts for 70% to 90% of the catch reduction, averaging 27.5% to 37.3% by mid-century, 35.3% to 66.7% by end-century relative to 2018, depending on climate change scenarios. Precipitation has a considerable impact if the temperature projection falls from average to upper bound, at 6.6% to 7.5% by mid-century and 7.6% to 9.4% by end- century. At the lower bound, the impact of rainfall is relatively tiny. The impact of typhoon maximum wind speed is almost insignificant, approximately 1% of the total catch in 2018. Fig 3 sums up the impact of temperature, precipitation and maximum wind speed on catch yield at lower, mean and upper bounds of each climate change scenario. Fig 3 illustrates that, under the RCP4.5, the capture yield will reduce by 35% from now to mid-century, then it will continue to shrink at a slower speed until the end of the century, rela- tive to 44% of the total catch in 2018. The contraction under RCP8.5 almost doubles the esti-

mates under RCP4.5, at 46% by mid-century and 78% by end-century. There might be almost no marine capture by the end of the century in the worst case. Price elasticities of demand and supply on fishery market Table 4 presents the demand function regression results using VHLSS data in 2018. The regression results (Table 4) indicate that the fishery demand depends negatively on its price and positively on the prices of substitutes such as pork and chicken. The fishery demand also depends on income per capita, household size, and other household characteristics. The demand for fishery products is higher in regions with more fish availability, ranking from Mekong River Delta, Southeast, North Central Coast, Red River Delta, Central Highlands, and the lowest demand is in Northern Mountains. The demand in coastal provinces is higher than in the inland. This result proves that fish consumption preference is likely to reduce when total catch decreases. The own-price elasticity of fishery demand is εD = -0.16, i.e., when the price goes up by 1%, the demand drops by 0.16%. Similar elasticities are obtained when data from VHLSS in 2012 and 2014 are used [80], indicating that the own-price elasticity of fisheries stands still over time. Since Vietnam is located along the seaside, artisanal fishing is widespread; fishery prod- ucts are popular and essential in the daily food consumption of households. These factors explain the steep elasticity of fishery demand in Vietnam compared to China [81] or the

Table 3. Changes in temperature, precipitation, and maximum wind speed of typhoons in early, mid and end periods of the 21st century in Vietnam relative to 2018. Average change in RCP4.5 RCP8.5 2018-2035 2046-2065 2080-2099 2018-2035 2046-2065 2080-2099 Temperature (˚C) (lower 10% – upper 90%) 0.7 (0.4–1.2) 1.4 (0.9–2.2) 1.8 (1.2–2.6) 0.9 (0.6–1.3) 1.9 (1.3–2.6) 3.4 (2.6–4.5) Precipitation (%) (lower 20% – upper 80%) 13.2 (1.4–24) 14.9 (1.6–28.7) 17.2 (4.1–30.5) 13.5 (4 – 24.5) 17.1 (7.3–27) 21.3 (8.5–35.5) Maximum wind speed (%) 2.0 5.0 8.0 2.0 6.0 11.0 Values in parentheses are confident intervals: lower 10% – upper 90% for temperature; and lower 20% – upper 80% for precipitation. Source: Based on MONRE [76, 77] https://doi.org/10.1371/journal.pone.0264997.t003 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 9 / 20