Decline in fish species diversity due to climatic and anthropogenic factors in Hakaluki Haor, an ecologically critical wetland in northeast Bangladesh

Md Saifullah Bin Aziz,Neaz A Hasan,Md Mostafizur Rahman Mondol,Md Mehedi Alam,Mohammad Mahfujul Haque

doi:10.1016/j.heliyon.2020.e05861

Md Saifullah Bin Aziz, Neaz A Hasan + Show 3 more

Open Access

https://doi.org/10.1016/j.heliyon.2020.e05861

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Abstract

This study evaluates changes in fish species diversity over time in Hakaluki Haor, an ecologically critical wetland in Bangladesh, and the factors affecting this diversity. Fish species diversity data were collected from fishers using participatory rural appraisal tools and the change in the fish species diversity was determined using Shannon-Wiener, Margalef's Richness and Pielou's Evenness indices. Principal component analysis (PCA) was conducted with a dataset of 150 fishers survey to characterize the major factors responsible for the reduction of fish species diversity. Out of 63 fish species, 83% of them were under the available category in 2008 which decreased to 51% in 2018. Fish species diversity indices for all 12 taxonomic orders in 2008 declined remarkably in 2018. The first PCA (climatic change) responsible for the reduced fish species diversity explained 24.05% of the variance and consisted of erratic rainfall (positive correlation coefficient 0.680), heavy rainfall (−0.544), temperature fluctuation (0.561), and beel siltation (0.503). The second PCA was anthropogenic activity, including the use of harmful fishing gear (0.702), application of urea to harvest fish (0.673), drying beels annually (0.531), and overfishing (0.513). Finally, the third PCA was loaded with the fishermen age (0.719), education (−0.767), and fishing experience (0.695) of the fishers. Deepening of beels could enhance dry season water availability and shelter the fish. Imposing fisheries regulations to reduce human activities is inevitable to sustain haor fisheries.

Highlights

The improvement of the fisheries sector is an important agenda of the Bangladesh government for nutritional supply, income generation, and employment opportunities for an increasing population, along with much needed foreign exchange earnings
For the years 2008 and 2018 a total of 63 fish species were recorded from the focus group discussions (FGDs), belonging to 12 taxonomic orders and 27 families
All the diversity indices determined in this study revealed that the fish species diversity of Hakaluki Haor decreased over time by seasons and taxonomic orders individual species were contributing evenly to the stock in recent years

Summary

Introduction

The improvement of the fisheries sector is an important agenda of the Bangladesh government for nutritional supply, income generation, and employment opportunities for an increasing population, along with much needed foreign exchange earnings. Capture fisheries and aquaculture contribute significantly to rural diets and national food security by providing protein-rich food. Total fish production (2.1 million MT in 2003; 4.2 million MT in 2019) has increased over the years owing to increasing aquaculture production [2]; concomitantly the relative growth of capture fisheries is in decline (Figure 1). The production of capture fisheries depends heavily on different open water resources such as rivers, beels, floodplains, and haors. In Bangladesh, haors contribute approximately 10% of the total capture fisheries production [2], this amount has reduced over time

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