Projecting marine fish production and catch potential in Bangladesh in the 21st century under long-term environmental change and management scenarios

Abstract

The fisheries sector is crucial to the Bangladeshi economy and wellbeing, accounting for 4.4% of national gross domestic product and 22.8% of agriculture sector production, and supplying ca. 60% of the national animal protein intake. Fish is vital to the 16 million Bangladeshis living near the coast, a number that has doubled since the 1980s. Here, we develop and apply tools to project the long-term productive capacity of Bangladesh marine fisheries under climate and fisheries management scenarios, based on downscaling a global climate model, using associated river flow and nutrient loading estimates, projecting high-resolution changes in physical and biochemical ocean properties, and eventually projecting fish production and catch potential under different fishing mortality targets. We place particular interest on Hilsa shad (Tenualosa ilisha), which accounts for ca. 11% of total catches, and Bombay duck (Harpadon nehereus), a low price fish that is the second highest catch in Bangladesh and is highly consumed by low-income communities. It is concluded that the impacts of climate change, under greenhouse emissions scenario A1B, are likely to reduce the potential fish production in the Bangladesh exclusive economic zone by <10%. However, these impacts are larger for the two target species. Under sustainable management practices, we expect Hilsa shad catches to show a minor decline in potential catch by 2030 but a significant (25%) decline by 2060. However, if overexploitation is allowed, catches are projected to fall much further, by almost 95% by 2060, compared with the Business as Usual scenario for the start of the 21st century. For Bombay duck, potential catches by 2060 under sustainable scenarios will produce a decline of <20% compared with current catches. The results demonstrate that management can mitigate or exacerbate the effects of climate change on ecosystem productivity.

Integrated ecological–economic fisheries models—Evaluation, review and challenges for implementation

“…Fulton et al, 2011;van Putten, Gorton, Fulton, Thebaud 2013;van Putten, Deng, et al, 2013;Fulton et al, 2014;. Fernandes et al, 2013;Fernandes, Kay, et al, 2016;Fernandes, Papathanasopoulou, et al, 2016;Queirós et al, 2015. Polovina 1984;Christensen & Pauly, 1992;Christensen & Walters, 2004;Walters and Martell 2004;Walters and Christensen 2007;Walters et al, 1997Walters et al, , 1999Walters et al, , 2000Christensen et al, 2011Christensen et al, , 2014Bevilacqua, Carvalho, Angelini, Steenbeek, & Christensen, In prep.…”

Marine Ecosystems and Fisheries: Trends and Prospects

“…25.2). A full description of these models is detailed in Fernandes et al (2016): here, a summary of these models is provided.…”

“…Size-based methods like this are useful in that they capture the basic metabolic properties and dynamics of marine food webs, describing energy flux and production by size class, independent of species' ecology . To make specific projections for key species, however, a second model, called SS-DBEM, was used (Fernandes et al 2013(Fernandes et al , 2016(Fernandes et al , 2017, which projects changes in species distribution and abundance over time while explicitly considering changes in production, dispersal and physiology as a result of changing ocean conditions, as well as species interactions (Fernandes et al 2013). The size-spectrum model was applied to explore potential changes in the total productivity of the Bangladesh Exclusive Economic Zone under both climate change and fishing scenarios and the SS-DBEM for the two target species (Hilsa shad and Bombay duck), for up to 2099.…”

“…The projections here indicate that catches of Bombay duck may not collapse as a result of unsustainable fishing practices and climate effects by 2060, contrary to projections for Hilsa. The reason for the different response compared to Hilsa relies on its different sensitivity to environmental and climate conditions and a broader range of feeding options (Fernandes et al 2016;Zhang and Jin 2014).…”

Untitled

“…Some point sources are ship breaking activities in Chittagong, municipal wastes of Khulna City (about 120-130 tons of wastes) (Hossain, 2006), and municipal wastes from Chittagong City through Karnaphuli river. The coastal population of Bangladesh has doubled since the 1980s, now reaching more than 16 million (approximately 10% of the total population), most of which are experiencing both poverty, and vulnerable to rapid experimental changes (Fernandes et al, 2016).…”