The Chalan beel in Bangladesh: Habitat and biodiversity degradation, and implications for future management

Abstract

This study provides an overview of the current resources and fisheries status of the Chalan beel, and identifies the scope of opportunities to evolve existing fisheries management strategies, focusing on fish biodiversity conservation. Chalan beel is the largest, most important watershed in the North Central Bangladesh, and covers an area of about 375 km 2 during the monsoon season. The watershed serves about 5 million people, predominantly through fisheries and agricultural activities. Although considerably degraded over time, Chalan beel still supports a diverse ichthyofauna of major importance to the local economy and people's livelihoods. The Chalan beel area incorporates 21 rivers and 93 smaller seasonal beels of varying size. Most of the rivers and beels are at risk of partial or total degradation, as a result of agricultural encroachment, siltation and other anthropogenic activities. During the study, ≈ 83% of the rivers, and 68% of the beels in the lean season, shrunk to 0-5% of their maximum (monsoon) water-spread area during the dry season (i.e. critical levels for survival of many fish species). A fish catch survey was carried out in the main fishing season (July to December) over two successive years in the three most important catchment areas; namely, the Gumani, Baral and Katagang Rivers. A total of 72 sampling episodes yielded 9818 individuals, representing 114 fish species. The most abundant fish species during the 2-year study period were punti (Puntius sophore and Puntius ticto), followed by chanda (Chanda nama and Parambassis ranga), chapila (Gudusia chapra) and tengra (Mystus vittatus). The study results indicate at least 19 fish species once considered abundant can now be classified as threatened, with a possibility of local extinction. The mean fish catch was 2.08 ± 0.49 kg, and 1.29 ± 0.32 kg per hour per person, by suti jal (set bag net -the most common gear used in the beel) in 2005 and 2006, respectively, with a significant (P < 0.05) variation among catches in months and years at all three sample sites. In 2005-2006, the annual fish production in Chalan beel was 12 217 tonnes, being less than half of the production observed in 1982. The stakeholders identified several major causes they thought were directly responsible for the continued decrease in fish production and biodiversity of the beel area. Several management strategies were suggested by the same stakeholders, and the findings are discussed in the context of overall developments in the Chalan beel fisheries related to habitat and biodiversity management.

Availability of small indigenous species (SIS) of fish in the Chalan Beel - the largest wetland of Bangladesh

“…The beel extends over the adjacent districts of Naogaon, Natore, Sirajgonj and Pabna. It is the most important watershed in North Western Bangladesh which covers an area of about 375 km 2 during monsoon season and 52-78 km 2 during the dry season (Hossain et al, 2009). There are 260 species of fresh water indigenous fin fish in the inland open waters of Bangladesh which are belonging to 55 families (Rahman, 1989).…”

Is current floodplain management a cause for concern for fish and bird conservation in Bangladesh's largest wetland?

“…The Padma River is one of the three largest rivers in Bangladesh. The area of the Chalan Beel is at present approximately 300-320 km 2 during the high flood period and it decreases to 50-75 km 2 during the dry season (Hossain et al, 2009;, when it comprises a series of isolated pools. As well as the Baral, which connects from the west, the Atrai River and numerous smaller channels run through the beel from the north.…”

“…The total length of the Baral is 147 km, and the channel can be up to 125 m wide and 6 m deep (Flowra, Islam, Jahan, Samad, & Alam, 2011). Both the Padma River (= Ganges in India) and the Chalan Beel make a small but significant contribution to the fishery of Bangladesh (together they produce~2% of the total inland water fish capture) and an important contribution to the livelihood of adjacent fishing communities (FRSS, 2015;Galib et al, 2009;Hossain et al, 2009). Both the Padma River (= Ganges in India) and the Chalan Beel make a small but significant contribution to the fishery of Bangladesh (together they produce~2% of the total inland water fish capture) and an important contribution to the livelihood of adjacent fishing communities (FRSS, 2015;Galib et al, 2009;Hossain et al, 2009).…”

“…The aim of this survey was not to identify all the bird species, or provide fully quantitative data (which are not available for wetland birds in the Chalan Beel area), but to provide a broader view of biodiversity in the Chalan Beel in relation to this and past studies that have concentrated on fish Hossain et al, 2009) and water quality (Sayeed et al, 2015). They were also asked to name and describe any bird which has become locally extinct in the last 20 years.…”

“…Unfortunately, the situation is the same in Bangladesh, a developing country, where in floodplains the emphasis has been on maximizing agriculture and fish production rather than sustaining aquatic and wetland biodiversity. This is particularly the case for natural wetlands such as the Chalan Beel, the largest wetland in Bangladesh, which is increasingly threatened by flood control, road building, agriculture and natural siltation (Hossain et al, 2009;Sayeed et al, 2015) and in which the yield of naturally recruited fishes is declining (Hossain et al, 2009). Despite these studies and the intensification of floodwater control in Bangladesh, little progress has been achieved in more sensitive management of floodplain inundation to support natural fisheries and aquatic biodiversity (e.g.…”