The impact of climate change on prawn postlarvae fishing in coastal Bangladesh: Socioeconomic and ecological perspectives
Highlights
► Prawn farming in Bangladesh remains dependent on the capture of wild postlarvae. ► Postlarvae fishing has been accompanied by concerns over recent climate change. ► Climatic variables have had adverse effects on ecosystem, thus availability of postlarvae. ► Postlarvae fishers face a variety of socioeconomic constraints. ► An integrated approach needs to be introduced to cope with the challenges.
Introduction
Freshwater1 prawn (Macrobrachium rosenbergii) farming is widespread in coastal Bangladesh, because of the availability of wild postlarvae2, suitable biophysical resources and favorable climatic conditions [1]. In Bangladesh, prawn farming remains dependent on the capture of wild postlarvae as the production of hatchery has been inadequate and farmers consider wild postlarvae to be of superior quality. Moreover, the survival of wild postlarvae has been reported to be much higher than that of hatchery-produced fry [2]. There are 80 prawn hatcheries in Bangladesh, although many are non-operational due to lack of knowledge of the complex hatchery technology, inadequate skilled manpower, and insufficient supply of wild broodstock. Hatchery production can supply about 1200 million postlarvae annually, only 25–30% of total demand [3]. Nevertheless, the Department of Fisheries in Bangladesh imposed a ban on wild postlarvae fishing in 2002. This ban primarily originated from concern for potential negative effects on by-catch (i.e., non-target species) that has an impact on biodiversity in coastal ecosystems [4]. However, this ban has not been strictly enforced because of the limited availability of hatchery fry and the lack of alternative livelihoods for poor people engaged in postlarvae fishing [5].
The livelihoods of around 400,000 people, many of them women and children, are associated with prawn and shrimp3 postlarvae fishing in coastal Bangladesh [5], [6]. Some 1500–2000 million postlarvae, valued at around US$30 million, are fished from the wild every year [7]. Postlarvae fishing contributes substantially to the local and national economy and also is a part of foreign exchange earnings. The prawn is a highly valued product for international markets, and thus, most prawns are exported, especially to the USA and Europe [2]. In 2010–2011 fiscal year, Bangladesh exported 54,891 t of prawn and shrimp valued at US$446 million, of which 30% was contributed by prawns [8].
However, postlarvae fishing has been accompanied by concerns over recent climate change. The country is already subject to climate extremes and prone to natural hazards. Climate change per se imposes threat to livelihood of postlarvae fishers. A decline in postlarvae fishing as a result of climate change could have dramatic consequences for the economy of Bangladesh. It is likely that mitigating the impacts of climate change on postlarvae fishing will require a combination of strategies and policies.
This paper seeks to broadly understand the likely consequences of climate change on prawn postlarvae fishing in coastal Bangladesh. The basic hypothesis of this study is that climate change has adverse impacts on postlarvae fishing. This paper examines of this hypothesis by assessing postlarvae fishing rate, ecological effects, and socioeconomic consequences. Finally, this paper sets out some preliminary conclusions about the adaptation to climate change.
Section snippets
Climate change and Bangladesh
Bangladesh is ranked first among countries vulnerable to climate change because of its geophysical position [9]. The country is subject to seasonal cycles of stress experiencing tropical climatic conditions, dominated by dry (January–March), pre-monsoon (April–June), monsoon (July–September), and post-monsoon (October–December) seasons. The growing risk results from a combination of climatic variables, including rainfall, flood, drought, cyclone, sea surface temperature, sea level rise, and
Study area
The study was conducted in the Mongla sub-district under Bagerhat district, a coastal area of the Bay of Bengal, situated in the southwest part of Bangladesh. The study site was selected on the Pasur River from Mongla through to Joymoni on the coast near the Sundarbans (Fig. 1). The total length of the Pasur River is about 142 km. The Bhairab River flows to the Rupsa River in Khulna and then this river flows south and is renamed as the Pasur which flows into the Bay of Bengal. The Pasur River is
Impacts on postlarvae fishing
According to the survey, a fisher daily caught an average 52 prawn postlarvae (Table 3). The average daily postlarvae fishing rate is higher in set bag net (71) than pull net (32). There was a significant difference (P<0.05) in postlarvae fishing rate between two gears, because of differences in fishing location, time, and duration of fishing. The average daily postlarvae fishing rate in pull net is higher for men (35) than women (29), because of longer fishing time, an average 5.12 and 4.90 h
Ecological features
The Pasur River is an ecologically healthy, robust and rich in biodiversity, particularly the availability of prawn postlarvae. Because of transitional zone between freshwater and seawater, the Pasur River serves as a seasonal habitat for many freshwater, brackishwater and marine species, and thus, richer than either freshwater or seawater in terms of biodiversity and ecosystem services [6], [37]. There is overwhelming evidence, however, that recent climate change has affected the ecosystem of
Socioeconomic impacts
Climate change poses a threat to socioeconomic wellbeing of the households of postlarvae fishers. According to the survey, the highest number of fishers (35%) identified poor income as the single most important impact of climate change, followed by inadequate food and nutrition (25%), poor housing (18%), health problems (15%), and drinking water crisis (7%) (Table 6).
Conclusions
The study found that climate change has severe impacts on prawn postlarvae fishing. The catch of postlarvae on the Pasur River showed a sharply declined over the years. The main reasons for declining postlarvae catches are directly related to climatic variables, including cyclone, salinity, sea level rise, water temperature, flood, rainfall, and drought. All of these climatic variables have also affected the physical operation of fishing practices by debilitated fishers. Future climate change
Acknowledgments
The study was supported through the Center for International Cooperation and Development (CICOPS) Fellowship, University of Pavia, Italy. The study was a part of the first author’s CICOPS Fellowship research at the University of Pavia, Italy. The views and opinions expressed herein are solely those of the authors.
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