Welfare impact of climate change on capture fisheries in Vietnam

reason for widespread coral bleaching, harming aquatic habitats [59]. In response, tropic fish may reduce their size by age for lower metabolism [4, 7]. Precipitation affects species’ growth by changing the water environment, such as salinity and contamination [60]. Typhoons keep fishers away from production, damage vessels [61], and increase marine contamination [62]. Southern Oscillation, including El Niño and La Niña, may alter fish flows and affect total catches [63, 64]. Heavy typhoons and tornados destroy coral reefs [48]. Changes in climate and marine conditions indirectly influence species, increasing the sensitivity of planktons, invertebrates, crustaceans, food web, and diseases [17, 59]. Fishing costs may increase due to incremental investment in vessels and gears to adapt to changes in fish stocks, species composition, and distribution [7]. Changes in migration behav- ior and fish stock distribution may lengthen the travel time of fishing boats, escalating fuel and ice consumption. A decrease in fish stocks and an increase in fishing costs will reduce produc- tion and shift the supply curve to the left side. On the demand side, total wild fish consumption depends on several factors such as popula- tion size, income, preferences, and the availability of substitutes, especially aquacultural prod- ucts. The relative fishery price is likely to go up when the potential catch goes down in the long run. Profit will alter following changes in catch yields, costs, and prices. The welfare benefits of consumers, producers, and society will be reallocated.

Following the flow of climate change impact on fisheries, this paper tests and measures (1) the capture reduction due to climate change, and (2) the potential changes in producer and consumer welfares. Research methods and data This study employs a set of several methods. Impact on catch yields is forecasted using a pro- duction function and the climate change scenarios for Vietnam. Then, a partial equilibrium analysis measures welfare changes. The price elasticity of demand is identified via a Marshal- lian demand function. The price elasticity of supply is inherited from the IMPACT model of IFPRI [29]. Different data sets are used for different methods. Production function The production function is widely used in literature to describe the relationship between out- puts and inputs in agriculture and fisheries [42, 47, 65–68]. Following Conrad [69], the Cobb- Douglas function is served as a base to develop the projection model. Two main production inputs are labor and capital; the latter is proxied by total fleet gears [70]. Climate change indi- cators such as sea surface temperature, precipitation, number of typhoons, maximum wind speeds of typhoons, and Southern Oscillation index are assumed to impact total catches. A dummy reflects the effectiveness of the Law on Fisheries, which was first introduced in 2003. The production function to evaluate impacts of climate change on capture fisheries in Viet- nam is formed as Eq (1): LnCatcht ¼ b0 þ b1T þ b2LnCapacityt þ b3LnLabort þ b4SSTt þ b5LnRainfallt þ b6Typhoont þ b7LnWindmaxt þ b8SOIt þ b9D þ εt ð1Þ

where βi and εt are coefficients and white noise, respectively. The North and the South of Vietnam were united in 1975. Therefore, the time-series data can only be collected uniformly from 1976 until recently, i.e., 2018. Annual data is employed due to the seasonal characteristics of capture production. Data are mined from their most reli- able sources: data on catch yield, capacity, and labors are collected from the Vietnam General 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 4 / 20