by Shelby Long
Nearly 400,000 Bangladeshi people are financially dependent on the fresh water prawn market. Bangladesh offers the natural resources and ideal climate to support prawn farming from wild postlarvae. In 2002, a ban was placed on the fishing of wild postlarvae by the Department of Fisheries in Bangladesh. However, this ban is not strongly enforced, so many locals who rely on the market to make a living continue to fish. Ahmed et al. (2013) examines the effect of climate change on prawn fishing in the Pasur River through variables, including cyclones, salinity, sea level rise, water temperature, flood, rainfall, and drought. The Pasur River ecosystem, more specifically the prawn postlarvae, is highly vulnerable to climate changes because it is only one meter above sea level. Researchers surveyed and interviewed local fishermen, government fisheries officers, policymakers, and non-governmental organization workers. They also conducted focus group discussions with fishers and local community members regarding the various climate-affected variables under study. Ahmed et al. determined that prawn postlarvae catch has gradually decreased by approximately 15% over the past five years, with cyclones being the most significant climatic variable affecting the catch. Decreases in postlarvae prawn catch impact the health and socioeconomic well-being of local fishermen, many of which are women and children.
Ahmed et al. examined the effects of climate change on the Pasur River by interviewing and surveying local fisherman and policy makers regarding prawn postlarvae fishing. They conducted the study over the course of six months on the Pasur River in the Bagerhat district in the southwest part of Bangladesh. Fishers were selected through stratified random sampling based on whether they used pull nets or set bag nets to fish. Pull net fishers were stratified based on gender. There were a total of 50 fishers in each group, which included 25 women in the pull net fishing group. Researchers observed their fishing techniques and recorded the total postlarvae caught for the 100 fishers. They interviewed the fishers regarding fishing practices, catch rate, perceived impacts of climate change on fishing, as well as the socioeconomic conditions of local fishers. Researchers also conducted 15 focus group discussions that focused on the same topics; however, these discussions were open to the community. Each focus group consisted of 6–15 persons, for a total of 147 people. Twenty-five key informants holding extensive knowledge about climate change effects on prawn postlarvae fishing were also interviewed. The informants included government fisheries officers, researchers, policymakers, and non-governmental organizations. The researchers entered the interview data into Microsoft Excel spreadsheets through which they conducted statistical analysis with Statistical Package for Social Science (SPSS).
Ahmed et al. were informed by Bangladeshi locals that salinity has increased by 2–5 ppt in the Pasur River in recent years, which can greatly constrain the availability of postlarvae. However, 12% of fishers interviewed reported that increases in water salinity have increased the availability of prawn postlarvae. This influx of saline water into agricultural land and the Pasur River, and the resulting availability of postlarvae, seems to have caused many coastal poor to switch from agricultural occupations to become prawn fishers. Based on surveys, 18% of set bag net fishers have moved to other fishing locations due to water level changes. The Pasur River water level is reported to have increased 2–4 cm in recent years as a result of the rising sea level. It is reported by local pull net fishers that the availability of postlarvae in shallow parts of the river has declined due to the water level change. Prawn postlarvae are also sensitive to water temperature. The suitable temperature for the postlarvae is 28–31 degrees Celsius, with a temperature above 33 °C being lethal. It has been reported that the Pasur River area has experienced a 1–2 °C increase in temperature in recent years. Ahmed et al. also determined through surveys of local fishers that increased air temperatures and heat waves have caused fishers to reduce their daily fishing time from 6.25 hours in 2006 to 6.07 hours in 2011 (Ahmed and Troell, 2010).
River floods result in the reduction of water salinity, as well as soil erosion and water turbidity, which negatively affect the availability of prawn postlarvae. Contaminated floodwater has had a strong negative effect on local fishers, resulting in health problems and decreased fishing effort. Ahmed et al. also examined the impacts of rainfall variation on prawn fishing. Higher levels of rainfall decrease the availability of postlarvae due to a reduction in water salinity. Many fishers have difficulty carrying out their work when there is heavy rainfall, such as when transporting postlarvae to markets (Ahmed and Troell, 2010). Researchers determined that increased frequencies of drought lead to a decrease in demand for postlarvae because there is less water available for prawn farming. Cyclones have destroyed habitat structure in the Pasur River, which likely affect the ecological interactions within the ecosystem (Almany, 2004). The availability of postlarvae prawns is greatly threatened by climate change processes that alter their habitat.
Climate change strongly impacts the socioeconomic wellbeing of postlarvae fishers and their families. The survey conducted by Ahmed et al. indicates that 35% of fishers identified poor income as the main impact of climate change. Twenty-five percent of fishers identified inadequate food and nutrition to be the next important impact. The survey also indicated that poor housing (18%), health problems (15%), and lack of clean drinking water (7%) were the next highest ranked negative impacts of climate change. Soil salinization has decreased the availability of agriculture-related occupations available to fishers. The lack of job options for fishers causes the cycle of poverty to continue among the group. Food insecurity is a major problem that causes malnutrition, especially among women and children. Cyclones result in a decrease in rice production and a decrease in fodder for cattle, which results in less available milk, meat, and eggs. Therefore, cyclones are a major contributor to food insecurity and malnutrition problems. Cyclones also exacerbate the poor housing conditions of the fishers. In addition to cyclone impacts, many fishers and their families struggle with drinking water shortages and related health issues, such as cholera, malaria, and diarrhea. According to Ahmed et al., adaptation strategies are necessary to combat these impacts, such as improved communication, transportation, and infrastructure.
Ahmed, N, Troell M, 2010. Fishing for prawn larvae in Bangladesh: an important coastal livelihood causing negative effects on the environment. Ambio 39, 20–29.
Ahmed, N., Occhipinti-Ambrogi, A., Muir, J., 2013. The impact of climate change on prawn postlarvae fishing in coastal Bangladesh: Socioeconomic and ecological perspectives. Marine Policy 39, 224–233.
Almany GR, 2004. Does increased habitat complexity reduce predation and competition in coral reef fish assemblages? Oikos 106, 275–284.