An assessment of impacts from shrimp aquaculture in Bangladesh and prospects for improvement.
Abstract
Aquaculture has become one of the fastest-growing economic subsectors of the Bangladesh economy, providing protein-rich food, source of employment and foreign currency earnings. Presently, the sector provides income and livelihood for more than 11 percent people of the country's 160 million people. Total farmed shrimp production in Bangladesh increased from 14 773 tonnes in 1986 to 132 730 tonnes in 2016, an almost 9.0-fold increase over the last 30 years. The land area under shrimp farming has increased from 70 331 ha in 1986 to 275 509 ha by 2016. The contribution of the farmed shrimp to total shrimp production and export has been increasing over the last 15 years at a rate of about 20 percent per year. The country earned foreign currency equating to USD450 million in 2015-16, through the export of 40 726 tonnes of frozen shrimp. In parallel with the significant contribution of the shrimp sector to the local and national economy, it has caused some negative impacts on local ecosystems. Ecological impacts include some deterioration of soil and water quality, depletion of mangrove forest, decrease in population of native fish and shellfish species, intrusion of saline water, water pollution and changes to local hydrology. There have also been some socioeconomic consequences, most acutely on the livelihood patterns of people living in coastal areas and on rural to urban migration, particularly among the poor and unskilled. Other impacts include deterioration of drinking water quality, loss of land for grazing of livestock and changes in agricultural cropping patterns, which has particularly affected the landless agricultural laborers. Social and environmental sustainability may have been overlooked during the expansion of shrimp farming. Losses due to disease, which are still a periodic problem for the sector, are a major indicator of the current unsustainable system of shrimp farming. At this stage, a paradigm shift is needed away from current shrimp farming practices to a more holistic and integrated approach that accounts for environmental integrity and social cohesion. Some modification and improvements have been made in recent years, and these should be extended. At the same time, incentives are needed for appropriate investment, to improve the physical infrastructure of ghers (shrimp ponds), and for adoption of new management methods. In this there is an important role for government in formulating appropriate policy and monitoring. Without a guiding policy on the development of the shrimp sector, private businessmen are likely to move ahead in an unplanned or unregulated way. To support this process, research is needed to better understand the effects of hydrology on biotic processes and of the biota on hydrology under the altered land-use scenario caused by shrimp farming. Alternative and innovative culture systems must be identified to form pathways to make shrimp aquaculture production more sustainable, including improvement in the hatchery sector, to reduce the environmental impact of wild-caught post-larvae and broodstock. Benefits for poor and marginal shrimp farmers and local stakeholders must be ensured, through improved understanding and identifying right ways to address the practical constraints under which poorer and less organized shrimp producers operate. Access to interest free or credit with minimal interest, through institutional reform, could help transform the shrimp farming sector, particularly for the poor and marginal shrimp famers, and post-larvae harvesters and traders. This will also prevent mal-adaptation, and increase diversification of livelihood strategies, as well as reduce the cost of farming. Institutional reform can also improve the enforcement of existing laws, particularly on the area of post-larvae harvesting, improve feed supply and hatchery provision, and improve fisheries diversity and conservation. Enforcement of regulations, and provision of insurance, would increase the safety of shrimp farmers. Finally, building shrimp farmer's human capital will underpin the creation of alternative livelihood activities. To evaluate the overall resource use and environmental impact caused by shrimp farming and to identify the hotspots and improvement options, a life cycle assessment (LCA) was conducted. Among different farming stages (i.e., fertilization, stocking, feeding and harvesting), feeding and fertilization were identified as the major contributors for the environmental impacts associated with the shrimp farming. This technical paper also assesses the major spatial risks of shrimp farming in southwest Bangladesh in relation to landscape deterioration, waterlogging and salinization of land and water, nutrients and material flow and impact on natural biodiversity. The ongoing measures to improve and streamline environmental performance of shrimp farming in Bangladesh are analyzed and a number of measures proposed, based on this activity and comprehensive stakeholder engagement.