Ichthyo-diversity assessment of the Old Brahmaputra river, Bangladesh: present stance and way forward

Abstract

The study was carried out to obtain information on the present status and trend of finfish diversity of the Old Brahmaputra river, Bangladesh. Samples were collected directly from a professional fishing boat caught by different nets, traps and hooks from January 2019 to December 2019. Together with 4 exotic species, a total of 49 species under 6 families were recorded. Though a biodiversity index of 3.65854 and a dominance index of 0.030929 represent the richness of ichthyo-diversity within the river, Synbranchiformes and Tetraodontiformes were not reported throughout the study period. Linear regression analysis showed a positive correlation between water height of the river and monthly abundance of the species found. Catch composition of catfishes and snakeheads slumped while barbs showed triumph over previous findings. A majority of fish recorded were within the least concern category according to IUCN (2015) but portions also belonged to critically endangered, endangered, and vulnerable categories as well. Therefore, conservation measures must be infixed in the Old Brahmaputra river to hold the fish diversity in a sustainable state.

Biodiversity, threats and recommendation for conservation of fishes in the Old Brahmaputra River

“…They assessed 253 fish species and among them 25.3% were threatened while endangered and vulnerable numbers were 30 and 25, respectively. This notion was also supported by other researchers (Rahman 2005, Hossain 2014, Galib 2015, Raushon et al 2027, Bashar et al 2020.…”

“…In connecting this, it is believed that many species are morphologically similar but genetically distinct like frogs (Hasan et al 2012) which need to explore in each and every rivers, canals, haors, boars etc. Most importantly, a few works of biodiversity study of fishes of the river Halda (Kabir et al 2015), Padma (Joadder et al 2015), Rupsha (Hossain et al 2016) and OBR in Mymensingh district (Raushon et al 2017, Bashar et al 2020, Galib 2015 has been done. However, no attempt was made to assess the biodiversity, threats and conservation policy of the mouth part of OBR (Fulchhari, Gaibandha to Melandah, Jamalpur).…”

Ichthyofauna of the Katamadari River, Bangladesh: Composition, Conservation Status and Threats

“…These alien species, introduced in the country by the government of Bangladesh over the years for the purpose of aquaculture (Khaleque, 2002), are now harvested round the year from the studied river. Similarly, Galib (2015) and Bashar et al (2020) reported the presence of four alien species in Brahmaputra River, including mirror carp, silver carp, bighead carp and sucker mouth catfish. Many alien species are invasive, posing a threat to the ecosystem and the biota that live there (Sarkar et al, 2012).…”

“…Similiarly, Parvez et al (2019) Decline and loss of fish species has been extensively documented in Bangladesh (Rahman et al, 2012;Galib et al, 2013;Mondol et al, 2015;Hossain et al, 2016;Sultana et al, 2018;Akter et al, 2020;Talukder et al, 2021) Siluriformes (18.75% and India (Mijkherjee et al, 2002;Chakraborty et al, 2006;Sarkar et al, 2008) as a result of aforementioned threats. Overfishing and catching of brood and juvenile fish identified as one of major causes of reduction of fish species in the rivers across the world including Bangladesh (Lakra et al, 2010;Rahman et al, 2012) Hossain et al, 2016;Sultana et al, 2016Sultana et al, , 2018Akter et al, 2020;Bashar et al, 2020;Talukder et al, 2021) from January 2019 to December 2019.…”

“…Cypriniformes were most dominant order constituting 35% of the total fish population followed by Siluriformes (32.50%. However, due to anthropogenic stressors especially overexploitation, habitat degradation, and pollution, the country's wild fish population has been declining over the years (Bashar et al, 2020;Hossain et al, 2016;Talukder et al, 2021)Siluriformes (18.75%, resulting in a significant reduction in the contribution of inland capture fisheries to total fish production, from 63 percent in 1982-83 to 28 percent in -19 (DoF, 2019. In addition, a total of 64 freshwater fish species have been categorized as threatened by IUCN Bangladesh, with 9 critically endangered, 30 endangered, and 25 vulnerable among them (IUCN Bangladesh, 2015).…”