A comprehensive review on the negative impacts on Sundarbans fisheries: Insights from the hydrological changes modulated by climate change and anthropogenic activities

The Sundarbans, the largest single block of transboundary mangrove that provides habitat, breeding and nursery grounds for fish and many other aquatic species, and livelihood for 3.5 million people, is currently under threat due to various reasons. In this review, we demonstrated the potential causes of alterations of the Sundarbans' hydrology and their likely impacts on its fisheries. Significant alterations in the Sundarbans' hydrology are induced by climatic variables (e.g., elevated temperature, cyclones, sea level rise, salinity fluctuation, erratic rainfall, floods, and droughts) and anthropogenic factors (e.g., pesticides, heavy metals, microplastics and oil spills, aquaculture, deforestation, harmful fishing practices, etc.). The interwoven impacts of climate change include destruction of habitats, crucial breeding and nursery grounds of fishes, degradation of water, shifting migration patterns, physiological disruption, loss of fish species, etc. Furthermore, human activities like deforestation, shrimp farming, oil spills, etc. produce both short- and long-term consequences on fisheries, such as poor water quality, chemical bioaccumulation, mortality, etc. Heavy metals and pesticides exceeded the acceptable limit in the edible tissues of fish and other aquatic organisms and may pose carcinogenic risk upon consumption. We identified major research gaps for future studies, including a lack of long-term assessment of climatic variables, insufficient data on pollutants, advanced climate modelling, etc. Lastly, we recommend reducing carbon footprint, forcing industries to use Effluent Treatment Plants (ETPs), declaring more conserved areas, initiating community-based management, etc. to address the issues brought on by climate change and anthropogenic activities that will ultimately help improve the overall fisheries resources in Sundarbans.