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Seasonal Variation and Community Structure of Fishes in the Mahananda River with Special Reference to Conservation Issues

Shams Muhammad Galib
Department of Fisheries, Faculty of Agriculture, University of Rajshahi, Rajshahi 6205, Bangladesh

Md Abdur Rashid
Department of Fisheries, Faculty of Agriculture, University of Rajshahi, Rajshahi 6205, Bangladesh

Nipa Chaki
Department of Fisheries, Faculty of Agriculture, University of Rajshahi, Rajshahi 6205, Bangladesh

A B M Mohsin
Department of Fisheries, Faculty of Agriculture, University of Rajshahi, Rajshahi 6205, Bangladesh

Md Abdur Razzaq Joadder
Department of Fisheries, Faculty of Agriculture, University of Rajshahi, Rajshahi 6205, Bangladesh

Abstract/ Executive Summary:

This study was carried out in the Mahananda River from January to December 2013 with a view to determining the seasonal variation and community structure of fishes along with some conservation issues. Monthly sampling was carried out using traditional fishing gears and fishes were identified based on morphometric and meristic characters. A total of 4082 individuals of native fish species were captured, analyzed and classified into 62 species belonging to 46 genera, 25 families and 9 orders. Cypriniformes and Siluriformes were the dominant fish orders represented by 19 species each and the most abundant family was Cyprinidae (14 species). In addition to indigenous individuals, 9 individuals of 2 exotic fish species (Hypophthalmichthys molitrix and Pangasius hypophthalmus) were also recorded. Among three sampling sites, S-1 was the most diversified in terms of not only the number of individual fish but also the number of species present represented by mean (±SE) individuals of 151.50±25.22 and species of 25.58±3.91. Three distinct fish groups of fish families were revealed from the cluster analysis of similarity. To improve the situation, control of illegal fishing gears, establishment of sanctuaries and legal protection for threatened species are recommended.

Keywords: Mahananda River, Seasonal variation, Community structure, Conservation, Threatened fish

Location: Chapi-Nababgonj

Start Date: 00-01-2013

End Date: 00-12-2013

Program Area: Animal Health and Management

Commodity: Fish

Objectives:

Objective of this study was to determining the seasonal variation and community structure of fishes along with some conservation issues.

Methodology:

Three sites of the Mahananda River were surveyed on monthly basis for a period of one year from January to December, 2013. Three sampling sites were Bholahat (S-1 or site I; 88º12’E, 24º56’N), (S-2 or site II; 88º15’E, 24º51’N), and Gomostapur (S-3 or site III; 88º15’E, 24º46’N). Sampling site was around 10 km far from each other. Fish were collected with a seine net (mesh 6x6 mm; 100x3 ft) and a cast net. Approximately 200 m of river segment was sampled during day (09:00-17:00 hours) and night (20:00-05:00 hours) at each sampling spot. Nine professional fishermen were employed for the purpose of sampling under the guidance of the research team. In case of cast net, 10 hauls were considered during each sampling. Collected fish specimens were identified and counted at the sampling sites. All the fish specimens were identified based on morphometric and meristic characters following Rahman (1989 and 2005) and Talwar and Jhingran (1991). Identified species were classified based on the classification system of Nelson (2006). Scientific names and authorities follow those of Froese and Pauly (2015). However, fish specimens, those were difficult to identify on the spot, were preserved in 10% formalin solution and brought to the Aquatic Biodiversity Lab of the Department of Fisheries, University of Rajshahi, Bangladesh for proper identification. Cluster analysis: Similarity values were calculated from the density data of various species at all the sampling sites. Bray-Curtis similarity analysis (Harper 1999) was performed in this regard to show level of similarity between different fish families. Global conservation status categories (Near Threatened, Least Concern, Vulnerable etc.) and global population trend (Decreasing, Stable etc.) are based on the online classification database developed by the International Union for the Conservation of Nature and Natural Resources (IUCN 2015). National conservation categories are based on book ‘Redbook of the Threatened Fishes of Bangladesh’ published by IUCN Bangladesh (2000). Local population status of fish species was determined by interviewing the professional fishermen in the study areas. A total of 75 fishermen, 25 from each sampling site, were asked to state the present status of each species compared to the status of concerned species 20 years ago. They were not asked to provide statistical data but to rank each species as: Decreasing or Increasing or Stable or Unknown, just like the population trends categories of IUCN. The rank of species came out from the majority of fishermen was considered only. All the fishermen had a fishing experience of at least 20 years in the river Mahananda and they were selected randomly for interview. This method was also used by Galib (2015).

Source of Information: Journal of Fisheries, Volume 4, Issue 1 Pages: 325-334 April 2016, eISSN 2311-3111, pISSN 2311-729X

Article Link (Online Journal): http://journal.bdfish.org/index.php/fisheries/article/view/139/JFish_325_334. DOI: dx.doi.org/10.17017/jfish.v4i1.2016.139

Funding Source:

Budget:

Total Budget (Tk.) :

Achievement/Findings:

Immediate conservation steps should be taken to conserve the existing fish species of the Mahananda River. Strict implementation of rules and regulation to control use of illegal fishing gears in river is strongly recommended. Establishment of sanctuary in the river is also suggested where there will be no fishing activities. Establishment of legal protection for certain threatened species can be a solution to save the decreasing aquatic biodiversity, especially those are rated Critically Endangered in Bangladesh

Knowledge Management: Journal