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In recent years, attaining gonadal maturation in smaller Hilsa (Tenualosa ilisha) has become a burning issue for Hilsa fishery of Bangladesh. Causes of early maturation are not yet clearly understood. Along with environmental parameters, genetic differentiation within the population was hypothesized as the main driver, and therefore, assessing the correlation between gonadosomatic index (GSI) and environmental factors and analyzing genetic diversity were set as objectives of the present study. To address these complex issues, six diverse habitats across Bangladesh were chosen for Hilsa sample collection. For GSI, gonad was dissected from fresh fish and preserved in Bouin's fluid for histological observation. Water quality parameters such as temperature, dissolved oxygen, pH, and salinity were also assessed. 35 fish from each habitat were used to extract and amplify DNA through the PCR technique, and genetic diversity was examined. Further, to draw a firm conclusion, the phylogenetic tree of the Hilsa population was developed by the unweighted pair-group method of arithmetic mean method based on the Cyt b gene of mitochondrial DNA. Results of GSI studies revealed that peak spawning months of T. ilisha were in October and February, where October showed the highest values in all six habitats. Histological examination showed different stages of gonadal development in different sizes and ages of Hilsa. Among all sampling sites, no statistical difference was observed for GSI value; however, smaller sized and aged Hilsa being ripped were evident in Gaglajur Haor and Kali River. Among the observed water quality parameters, temperature correlated with GSI strongly. Increased GSI was observed with temperature augmentation from downstream to upper stream, irrespective of body size and age. A perplex correlation between dissolved oxygen of observed habitats and GSI was executed. Other physico-chemical parameters viz. pH and salinity exhibited weak and moderate positive associ

This study examines social, economic, and ecological adaptation strategies for small-scale Hilsa fishers in Bangladesh's coastal areas in response to the impacts of climate change. The Hilsa fishery and the communities dependent on it are vulnerable to the adverse effects of climate change, making it imperative to adopt mechanisms to cope with its consequences. Using a mixed-method approach, including in-depth interviews, focus group discussions, and a review of secondary resources, this study explores adaptation policies, relevant factors, and aspects of the Hilsa fishing community's response to climate change. The study finds that climate change poses a significant threat to biodiversity, potentially leading to changes in fish migration systems and declining fish stocks. The Hilsa fishers perceive that addressing climate change requires policies that combat poverty, preserve or restore biodiversity, and enhance ecosystem services simultaneously. The study identifies social adaptation strategies such as risk reduction, social relationships, and participation in adaptation planning. Economic adaptation strategies include alternative livelihood development, aquaculture, and access to credit. The study also suggests that effective ecological adaptation actions include developing climate change knowledge and fishers' local ecological knowledge, establishing more effective sanctuaries, and developing networks among protected areas. The study concludes that formal adaptation policies should consider fishers' interests and practices for adaptation, including their knowledge of social, economic, and ecological issues, to address the impacts of climate change on small-scale fishers and their communities.

Hilsa: The fish that is being loved to death.