Welfare impact of climate change on capture fisheries in Vietnam

households in many areas, especially in countries with warm seas. It sometimes benefits other countries, such as those with cold water [17–22]. However, fisheries in both regions might get damaged due to water quality degradation and the spread of diseases [23–25]. Several studies have quantified the impacts of climate change on fisheries, revealing differ- ent magnitudes in different places and species. The catch potential of Indian mackerel for the period 2020-2100 under RCP6.0 will decline from 2035 (+14%) to 2100 (−44%) [26]. The pre- dicted loss of the fishery sector in Guyana under A2 and B2 scenarios in 2050 are from 20 to 34 million USD at the discount rate of 1% per year [27]. Dey, Gosh [28] report that total fish demand will likely surpass domestic fish production in 2050 in Fiji due to the declining trend of fish capture in climate change scenarios. The global economic costs of mollusk due to ocean acidification could be over 100 billion USD with an assumption of increasing demand of mol- lusks at expected income growths and a business-as-usual emission trend towards the year 2100 [29]. Cheung, Lam [30] forecast a drop of up to 40% catch potential due to climate change for 2005-2055 in the tropics. Since Vietnam is located in a tropical region, climate change is likely to affect its fishery sector adversely. Lam, Cheung [22] estimate change in global fishery reve- nues under climate change and estimate a reduction of 11.3% between 2010 and 2050 in Viet- nam. The Vietnam Fisheries Development Strategy for 2021-2030 [31] projects a shrink in

catch yield from 3.8 million tons in 2020 to 2.8 million tons in 2030. Fisheries are a pro-poor economic sector and important nutrition source in Vietnam [31]. This sector provides jobs to 3 million laborers, accounting for 17% of total laborers in agricul- ture and 5.6% in the national labor force [3]. Fishery products meet 40% of food consumption demand, contributing significantly to ensuring national food security and nutrition require- ments [32]. Climate change seems to influence both fishery laborers and consumers. Reviews of the literature reveal that most studies related to impacts of climate change focus on the gains or losses of fish stocks, yields and revenues, while the welfare of fishery producers and consumers under climate change is not well understood. When the supply falls short of demand, the price will increase, leading to the uncertain fluctuation in welfares of market play- ers. The study aims to identify the welfare changes via a partial equilibrium analysis and sup- porting methods. It is the first attempt to quantify the losses, or gains, if it is the case, of wild fish consumers, producers, and both due to climate change in Vietnam. Conceptual framework There are several approaches to analyze the various aspects of climate change impacts, such as vulnerability [5, 33–36], adaptation and mitigation [6, 37–41], and economic impact [27, 28, 42–46]. Since welfare is the primary concern of this study, its approach should fall in the range of economic issues. Hence, we follow Brander [4] and Sumaila [7] to build the conceptual

framework, as it allows us to consider the impact of climate change on fishery productions, costs, revenues and incomes. There is ample literature depicting the impacts of climate change on aqua species [2, 4, 7, 17, 24], which includes instabilities in physical and biological ecosystems, primary and second- ary productivity, and fish stock distribution. These volatilities then affect fishing costs, prices, resource rents, revenues, and profits [4, 7, 47]. Fig 1 describes the flow of climate change impacts on the welfares of fishery consumers and producers. As shown in Fig 1, the sequence of impacts starts from climate change, which is an irrevers- ible trend in the 21st century [48]. Its manifestations include changes in weather and ocean conditions: higher sea surface temperature in most oceans, the most significant change is in the tropics and subtropics of the Northern hemisphere [48, 49]; changes in ocean currents and 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 2 / 20