IOSR Journal of Environmental Science, Toxicology and Food Technology (IOSR-JESTFT) e-ISSN: 2319-2402,p- ISSN: 2319-2399.Volume 10, Issue 9 Ver. II (Sep. 2016), PP 37-43 www.iosrjournals.org DOI: 10.9790/2402-1009023743 www.iosrjournals.org 37 | Page Effect of Degraded Ecosystem on Fish Biodiversity in the Old Brahmaputra River, Bangladesh and Its Conservation Measures Sania Afrose 1 , Nesar Ahmed 2 1 Master in Marine and Lacustrine Science and Management, Vrije Universiteit Brussel, Belgium 2 Faculty of Fisheries, Bangladesh Agricultural University (BAU), Bangladesh Abstract : The study was conducted about the ecosystem-based approach on fisheries management of the Old Brahmaputra River in Mymensingh region, Bangladesh. The primary area for the study was in the Old Brahmaputra River adjacent to the Bangladesh Agricultural University, Mymensingh. This research focused on the identification of proper management strategies for the conservation of fish biodiversity. There are degraded ecosystems and declining biodiversity have found during the study. According to the survey, fishing pressure and overexploitation were responsible for almost 42%, and water pollution caused about 35% loss of fish biodiversity. Around 17% and 10% loss of fish biodiversity were caused by Change of river course, and the habitat degradation respectively within the study area. These have been created a great impact on river ecology and surrounding river conditions. As a result, the water quality is deteriorating day by day and the availability of fish species and other aquatic biodiversity is decreasing gradually. During the survey, 19 species were also found at a risk of being endangered. This study identified possible ways to achieve a rich fish biodiversity in the Old Brahmaputra River with social, economic and environmental aspects. The specific recommendations are included community-based fisheries management, establishment of sanctuary, control of pollution, maintenance of fishing gears and the implementation of the fish act for the conservation of fish biodiversity of the Old Brahmaputra River. Keywords: Conservation measures, Fish biodiversity, Old Brahmaputra River, Riverine ecosystem I. Introduction Fisheries make crucial contributions to the world’s wellbeing and prosperity. In the last five decades, world fish food supply has outpaced global population growth, and today fish constitutes an important source of nutritious food and animal protein for much of the world’s population [1]. Fish and fisheries are the indispensable part of life and livelihood of the people of Bangladesh too since immemorial time. It is an element of the country’s cultural heritage [2]. Total global capture production in inland waters has increased dramatically since the mid-2000s. Total production amounted to 11.2 million tonnes in 2010, an increase of 30% since 2004 [1].Bangladesh is one of the world's leading inland fisheries producer with an annual production of fish was 1.05 million metric tonnes which constituted 34.45% of total catch in 2011 [2]. The main factor that threatens marine fish biodiversity globally is fishing [3, 4]. For example, worldwide over 40 local populations of marine fishes have gone extinct as a result of overexploitation [3]. These local losses represent an erosion of global biodiversity. Moreover, stresses due to other factors such as climate change, habitat loss, invasive species, eutrophication, and pollution can accentuate fishing-induced declines and inhibit or prevent recoveries [4]. Biodiversity and its conservation are regarded as one of the major issues of enabling sustainable use of natural resources and is essential for the Old Brahmaputra River. Conservation helps fish production to be more sustainable while at the same time maintains diversity. Conserving diversity also improves the likelihood of maintaining minimal viable populations of rare and late-successional species. Maintaining biodiversity is important because it is not always possible to identify which individual species are critical to aquatic ecosystems sustainability. Many fish species may provide genetic material and may serve as ecological indicators. Diversity reduces disease problems and encourages recovery from disturbance. Aquatic conservation strategies support sustainable development by protecting biological resources in ways that will preserve habitats and ecosystems. In order for biodiversity conservation to be effective, management measures must be broad-based [5]. The effects of changes in biodiversity on ecosystem functioning are becoming evident, although there is uncertainty, many fishery-induced changes in species and size composition of fish communities are now well documented by Garcia et al. [4]. What has recently become clearer is that these changes affect the structure and functioning of marine ecosystems, including the biomass of species at lower tropic levels [6]. Fisheries managers and policy makers must, therefore, take a precautionary approach in their management of fish diversity. Islam and Ahmed [7] implied that mass destruction of valuable aquatic organisms by shrimp seed collectors is a serious threat to biodiversity and coastal ecosystem integrity. Kalpana and Seth [8] studied on the conservation of biodiversity and reported that the factors adversely affecting aquatic communities are