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Introduction: The proteome profile of the female Tenualosa ilisha (Hamilton, 1822), a species of great ecological and economic importance, across various age groups was investigated to comprehend the functional dynamics of the serum proteome for conservation and aquaculture, as well as sustain the population. Methods: Advanced liquid chromatography-tandem mass spectrometry LC-MS/MS-based proteomic data were analysed and submitted to the ProteomeXchange Consortium via PRIDE (PRoteomics IDEntifications database). Bioinformatics analysis of serum proteome have been done and it showed different proteins associated with GO Gene Ontology () terms, and the genes associated with enriched KEGG (Kyoto Encyclopedia of Genes and Genomes) pathways (such as phagosome, mTOR, Apelin signalling pathways, herpes simplex virus) implicated in immune responses. Results: The expression levels of important immunological proteins, such as those involved in cellular defence and inflammatory responses, were significantly different age-dependently. In this study, we annotated 952, 494, 415, and 282 proteins in year classes IV, III, II, and I Hilsa, respectively, and analysed their Protein-Protein Interaction (PPI) networks based on their functional characteristics. From year classes I to IV, new proteins appeared and were more than three-fold. Notably, class I hilsa displayed a lower abundance of proteins than class IV hilsa. Discussion: This is the first study, to the best of our knowledge, to report the analysis of the serum proteome of hilsa at different developmental stages, and the results can help improve the understanding of the mechanisms underlying the different changes in protein enrichment during migration in hilsa. This analysis also offers crucial insights into the immune system for hilsa conservation and management. [ABSTRACT FROM AUTHOR]

Background and Aim: Allergenic foods can trigger skin conditions, yet their impact in Bangladesh remains underexplored. This study aims to investigate the potential association between exposure to allergenic foods and the development of skin disease across Bangladesh. Methods: We conducted a cross‐sectional survey with 970 respondents from the divisions of Dhaka, Sylhet, Rangpur, and Chattogram who self‐reported skin disease triggered by food allergens. We analyzed the data using multiple response analysis and principal component logistic regression. Results: Approximately 64% of respondents had skin disease attributable to allergenic foods, with a relatively higher proportion among females (52%) than males (48%). Beef (67%), Brinjal (47.1%), Hilsa (45.8%), and Shrimp (23.7%) were the most frequently cited allergenic foods. Principal component logistic regression identified two highly significant principal components: the first representing Hilsa, Beef, and Brinjal (odds ratio = 2.256), and the sixth reflecting Corn (odds ratio = 1.342). Individuals who consumed foods with high loadings of the first principal component were 125.6% more likely to develop skin disease than nonconsumers, while those exposed to Corn had a 34.2% higher risk. Conclusion: The findings highlight prevalent allergenic foods in Bangladesh and their substantial impact on skin health, underscoring the need for dietary awareness and tailored interventions to mitigate allergic skin conditions in this population. [ABSTRACT FROM AUTHOR]

Antioxidants play a crucial role in maintaining health by scavenging free radicals that causes cellular damage and accelerates aging and disease. The present study focuses on the antioxidant levels in various organs of Hilsa fish, both male and female, with a weight range of 50 g to 780 g collected from the Hooghly River in the lower Gangetic plain. The study utilized commercially available free radicals such as, viz., 2,2'-azinobis-[3-ethyl-benzothiazoline-6-sulfonic acid] and ferric reducing antioxidant potential to measure the scavenging activity. The results indicated that female Hilsa fish possess higher levels of antioxidants (93.79 ± 0.26) compared to male counterparts (84.50 ± 0.65) in all organs, with levels increasing proportionally with weight. Interestingly, in males, the serum antioxidant profile was higher in the lower weight group (50-100 g), whereas, in females, the highest antioxidant activity was observed in the weight range of 300 g to 400 g. The present study was attempted for the first time to characterize the antioxidant distribution pattern in the different organs of Hilsa. These findings suggest that Hilsa fish organs, including serum, contain high levels of antioxidants that could significantly benefit human nutrition and potentially will contribute to anti-aging effects by incorporating Hilsa to their diet, which needs further clinical study. [ABSTRACT FROM AUTHOR]

Microplastics (MPs) pollution is a profound problem around the world yet it's study on the effect on zooplankton including copepods are very limited. The study was conducted between January 2021 and January 2022 in the Lower Meghna Estuary to investigate MPs ingestion in two different family of copepod: Calanoid and Cyclopoid. A method of acid digestion along with Scanning Electron Microscope (SEM) was used to identify MPs ingested by copepods from the conducted area. However, three types of MPs namely fiber, fragment and foam were extracted from this copepod biomass. Fibers represent highest (> 50%) of the ingested MPs from both group of copepod that exceed fragments and foams in all sampling stations. The overall ingestion rate of Calanoid was found higher (0.084 ± 0.002 particles/individual) compared to the Cyclopoid group (0.077 ± 0.001 particles/individual). The results of the study have effectively illustrated that copepod, obtained from multiple sampling sites within the Lower Meghna Estuary, display a propensity to ingest MPs and subsequently endangering the food security of seafood industry. [ABSTRACT FROM AUTHOR]

Abstract Background and Aim Allergenic foods can trigger skin conditions, yet their impact in Bangladesh remains underexplored. This study aims to investigate the potential association between exposure to allergenic foods and the development of skin disease across Bangladesh. Methods We conducted a cross‐sectional survey with 970 respondents from the divisions of Dhaka, Sylhet, Rangpur, and Chattogram who self‐reported skin disease triggered by food allergens. We analyzed the data using multiple response analysis and principal component logistic regression. Results Approximately 64% of respondents had skin disease attributable to allergenic foods, with a relatively higher proportion among females (52%) than males (48%). Beef (67%), Brinjal (47.1%), Hilsa (45.8%), and Shrimp (23.7%) were the most frequently cited allergenic foods. Principal component logistic regression identified two highly significant principal components: the first representing Hilsa, Beef, and Brinjal (odds ratio = 2.256), and the sixth reflecting Corn (odds ratio = 1.342). Individuals who consumed foods with high loadings of the first principal component were 125.6% more likely to develop skin disease than nonconsumers, while those exposed to Corn had a 34.2% higher risk. Conclusion The findings highlight prevalent allergenic foods in Bangladesh and their substantial impact on skin health, underscoring the need for dietary awareness and tailored interventions to mitigate allergic skin conditions in this population.

IntroductionThe proteome profile of the female Tenualosa ilisha (Hamilton, 1822), a species of great ecological and economic importance, across various age groups was investigated to comprehend the functional dynamics of the serum proteome for conservation and aquaculture, as well as sustain the population.MethodsAdvanced liquid chromatography-tandem mass spectrometry LC-MS/MS-based proteomic data were analysed and submitted to the ProteomeXchange Consortium via PRIDE (PRoteomics IDEntifications database). Bioinformatics analysis of serum proteome have been done and it showed different proteins associated with GO Gene Ontology () terms, and the genes associated with enriched KEGG (Kyoto Encyclopedia of Genes and Genomes) pathways (such as phagosome, mTOR, Apelin signalling pathways, herpes simplex virus) implicated in immune responses.ResultsThe expression levels of important immunological proteins, such as those involved in cellular defence and inflammatory responses, were significantly different age-dependently. In this study, we annotated 952, 494, 415, and 282 proteins in year classes IV, III, II, and I Hilsa, respectively, and analysed their Protein–Protein Interaction (PPI) networks based on their functional characteristics. From year classes I to IV, new proteins appeared and were more than three-fold. Notably, class I hilsa displayed a lower abundance of proteins than class IV hilsa.DiscussionThis is the first study, to the best of our knowledge, to report the analysis of the serum proteome of hilsa at different developmental stages, and the results can help improve the understanding of the mechanisms underlying the different changes in protein enrichment during migration in hilsa. This analysis also offers crucial insights into the immune system for hilsa conservation and management.

Abstract Nutritional constituents and bacterial community of hilsa (Tenualosa ilisha) at different stages of dry salt-fermentation; namely, F1 (after 2 days of salting), F2 (after 5 days of salting) and F3 (ripe product after 15 days of salting) was studied. Dry salt-fermentation did not negatively affect proximate biochemical composition. Total protein content in F1, F2 and F3 was 10.14, 22.30 and 16.21 mg/ml, respectively. With progression of ripening process, protein solubility gradually decreased. In all stages, about 98% protein digestibility was found. TBARS (Thiobarbituric acid reactive substances) values at F1, F2 and F3 stages was 0.30, 0.41 and 0.95 mg MDA/kg, respectively and within acceptable limit. A total of 3,248 OTUs were found. Of the identified 48 phyla, Proteobacteria (66%), Firmicutes (18%) and Bacteroidota (11%) were abundant at F1 stage but Firmicutes (82%) and Proteobacteria (9%) were dominant at F3 stage. Significant differences in the microbial β-diversity among initial, interim and ripe product were observed. There was no significant α-diversity difference at individual stages of dry salt-fermentation of hilsa. Functional gene profile revealed that, in the final product microbial genes related to organismal systems replaced human disease related genes found in initial and interim product. These findings provide new clues for in-depth characterization of salt-fermented foods from viewpoint of food chemistry and microbiology. Graphical Abstract

Nutritional constituents and bacterial community of hilsa (Tenualosa ilisha) at different stages of dry salt-fermentation; namely, F1 (after 2 days of salting), F2 (after 5 days of salting) and F3 (ripe product after 15 days of salting) was studied. Dry salt-fermentation did not negatively affect proximate biochemical composition. Total protein content in F1, F2 and F3 was 10.14, 22.30 and 16.21 mg/ml, respectively. With progression of ripening process, protein solubility gradually decreased. In all stages, about 98% protein digestibility was found. TBARS (Thiobarbituric acid reactive substances) values at F1, F2 and F3 stages was 0.30, 0.41 and 0.95 mg MDA/kg, respectively and within acceptable limit. A total of 3,248 OTUs were found. Of the identified 48 phyla, Proteobacteria (66%), Firmicutes (18%) and Bacteroidota (11%) were abundant at F1 stage but Firmicutes (82%) and Proteobacteria (9%) were dominant at F3 stage. Significant differences in the microbial β-diversity among initial, interim and ripe product were observed. There was no significant α-diversity difference at individual stages of dry salt-fermentation of hilsa. Functional gene profile revealed that, in the final product microbial genes related to organismal systems replaced human disease related genes found in initial and interim product. These findings provide new clues for in-depth characterization of salt-fermented foods from viewpoint of food chemistry and microbiology. [ABSTRACT FROM AUTHOR]

Tenualosa ilisha popularly known as 'Hilsa' is one of the most commercially important euryhaline food fish species in South Asian countries. Co-infection of Fusarium incarnatum FHHS2 and Acinetobacter bohemicus FHHK1 was reported for the first time in captive-reared pre-adult T. ilisha (average length 22.30 ± 0.92 cm and weight 93.48 ± 28.06 g) that had manifested skin lesions in freshwater pond during November–December 2022. The infected fish showed lethargy, abnormal swimming behaviour, blackening of gills, red streaks on the fins, erosions of the skin, and sloughing of the scales resulting in 40% mortality of the stock. Microscopic observation revealed the presence of aerial slightly curved conidia, septate macroconidia, and randomly spread microconidia. The fungal species was confirmed as F. incarnatum FHHS2 (NCBI GenBank accession number OR030402) by ITS sequencing. It clustered with known pathogenic F. incarnatum (NCBI Accession no. AY633745) counterpart associated with black gill disease of Penaeus monodon Fabricius (99.46% homology) in phylogenetic tree. We have also isolated, identified, and characterised A. bohemicus FHHK1 from the infected fish which clustered with A. bohemicus reported in the lakes of Indian subcontinent (100.00% homology). No parasite was found in different organs of the moribund hilsa shad. Significant histopathological alterations were observed in the skin, gill, and kidney of infected hilsa. Our study records the first report of F. incarnatum FHHS2 and A. bohemicus FHHK1borne infection in hilsa during its domestication in freshwater pond. [ABSTRACT FROM AUTHOR]

Mislabeling of Juvenile hilsa, (Tenualosa spp.) or Jatka fish as Chapila (Gudusia chapra) is a recognized problem in Bangladesh resulting in fraudulence to consumers, illegal harvesting, and ultimately the degradation of hilsa fish production. We applied DNA barcoding using mitochondrial COX 1 gene together with morphometric analysis to resolve the mislabeling or misidentification of Clupeid fishes differentiating mainly hilsa fish from chapila fish. This study confirmed the identification of Jatka fish (Tenualosa sp.) that was mislabeled with chapila (Gudusia chapra). DNA barcoding identified the four species of clupeid fishes (Tenualosa ilisha, Gudusia chapra, Sardinella jussieu and Tenualosa toli) with phylogenetic placement. These cases may reflect a clear picture of admixture of locally sold mislabeled Jatka, which may warrant more comprehensive analyses. Mislabeling records of Juvenile hilsa established in the present study may also have implications for the harvesting, marketing and consumption the national fish of Bangladesh. [ABSTRACT FROM AUTHOR]

The hilsa (Tenualosa ilisha) fishery in Myanmar is of importance as it provides an income for around 1.6 million artisanal low-income fisher households and generated USD 237.32M in export earnings from 156,000 metric tons in 2021. Fisheries Performance Indicator assessments have shown that the fishery, both artisanal and industrial, is close to economic collapse. Research was undertaken to find ways to improve the management of the fishery including studies to establish the migration routes and spawning periodicity of hilsa in addition to socioeconomic assessments and business case valuations to recommend finance mechanisms for improved management and maintenance of the fishery. Results indicate that the closed season for hilsa fishing misses the main spawning period in September. In addition, the chemical analysis of hilsa otoliths shows the importance of upstream spawning grounds - some 800km from the sea. Recommendations were made, and enacted March 2022, regarding the need for a new September closed season in addition to no-take hilsa sanctuaries along the main migration routes. A value was placed on the hilsa fishery at close to USD800M per annum. A USD100M annual investment cost is suggested to ensure that the new and old closed seasons are respected by licensed and unlicensed fishers. This investment could be generated by recommended fiscal reforms to provide incentives for fishers to respect the new fishing restrictions. Transboundary fisheries management opportunities are being advanced by informal tripartite scientific collaboration between Bangladesh, India and Myanmar. Social aspects, involving fisheries co-management with artisanal fisher communities and local government authorities, need to be continued to demonstrate the benefits of improved fisheries management in terms of the expected sustainable yields and a move away from potential economic fishery collapse. [ABSTRACT FROM AUTHOR]

Antioxidants play a crucial role in maintaining health by scavenging free radicals that causes cellular damage and accelerates aging and disease. The present study focuses on the antioxidant levels in various organs of Hilsa fish, both male and female, with a weight range of 50 g to 780 g collected from the Hooghly River in the lower Gangetic plain. The study utilized commercially available free radicals such as, viz., 2,2′-azinobis-[3-ethyl-benzothiazoline-6-sulfonic acid] and ferric reducing antioxidant potential to measure the scavenging activity. The results indicated that female Hilsa fish possess higher levels of antioxidants (93.79 ± 0.26) compared to male counterparts (84.50 ± 0.65) in all organs, with levels increasing proportionally with weight. Interestingly, in males, the serum antioxidant profile was higher in the lower weight group (50–100 g), whereas, in females, the highest antioxidant activity was observed in the weight range of 300 g to 400 g. The present study was attempted for the first time to characterize the antioxidant distribution pattern in the different organs of Hilsa. These findings suggest that Hilsa fish organs, including serum, contain high levels of antioxidants that could significantly benefit human nutrition and potentially will contribute to anti-aging effects by incorporating Hilsa to their diet, which needs further clinical study.

The length-weight relationship (LWR) and relative condition factor are widely used as the most important biological parameters to infer the growth pattern and well-being of fishes. The aim of our study was to investigate the growth parameters of the LWR in different growth phases of Hilsa (Tenualosa ilisha), a flagship species of Bangladesh, and compare its relative condition factors across its major habitats. Fish from various rivers in Bangladesh and the Bay of Bengal were sampled, their length-weight growth parameters were measured and subjected to statistical analysis with pooled data from other studies. An isometric growth pattern in Hilsa was predominantly found in the size classes of 25 ≤ TL (total length) Bay of Bengal > Andharmanik > Biskhali > Tetulia > Padma. Additionally, the relative physiological well-being of Hilsa from the river Padma and Tetulia was poor compared to that of other habitats. A more in-depth analysis is required to determine the factors that can influence Hilsa's growth and well-being in relation to habitat quality. The present findings have significant relevance for fisheries biologists and managers in understanding and interpreting Hilsa's ecology, relative well-being of populations of same or contrasting habitats, demographic assessment, and for better management of Hilsa in the future.

Hilsa (Tenualosa ilisha) is a premium table fish in the eastern and some parts of the north-eastern region of India, especially for the Bengali community, contributing uniquely to the societal and economic significance of artisanal fisheries of the country. The major distribution of the fish species in India lies in the Bhagirathi-Hooghly component of the Ganga River system. The aim of the study was to examine if traditional Hilsa fisheries in India are sustainable as the livelihood of artisanal fishers in light of the socio-economic conditions of Hilsa fishers in West Bengal. Structured socio-economic surveys were conducted with 402 fishermen from the upper stretch of river Hooghly to its lower stretch (300 km) in West Bengal during 2020-2021. The average monthly income of the Hilsa fishers in the lower stretch of river Hooghly (Godakhali) (₹25,000-30,000/USD 301-361) was higher than that in the upper stretch at Farakka (₹10,000-15,000/USD 120-180). However, fish species other than Hilsa are generating significantly higher returns for 56% of fishers in the Hooghly district; 40% of Hilsa fishers in South 24 Parganas and Murshidabad (Farakka) districts are engaged in non-fishery activities for livelihood. There are significant differences between Hilsa fishers with other fisheries as secondary occupations and those with non-fishery activities as secondary occupations in terms of socio-economic characteristics. These imply that Hilsa fisheries are profitable as a continued traditional livelihood, but it alone is not sufficient enough to support the livelihood of the artisanal fishers. This indicates the threatened economic sustainability of the Hilsa fisheries sector at present. Considering the high market demand for Hilsa in the eastern and north-eastern regions of India and the market complexities, more significant investments need to be channeled into the Hilsa fisheries of the northern Bay of Bengal region. Such investments encompass a wholesome approach, including more governmental initiatives for conservation and management. [ABSTRACT FROM AUTHOR]

Background: The host-microbe interactions are complex, dynamic and context-dependent. In this regard, migratory fish species like hilsa shad (Tenualosa ilisha), which migrates from seawater to freshwater for spawning, provides a unique system for investigating the microbiome under an additional change in fish’s habitat. This work was undertaken to detect taxonomic variation of microbiome and their function in the migration of hilsa. Methods and results: The study employed 16S rRNA amplicon-based metagenomic analysis to scrutinize bacterial diversity in hilsa gut, skin mucus and water. Thus, a total of 284 operational taxonomic units (OTUs), 9 phyla, 35 orders and 121 genera were identified in all samples. More than 60% of the identified bacteria were Proteobacteria with modest abundance (> 5%) of Firmicutes, Bacteroidetes and Actinobacteria. Leucobacter in gut and Serratia in skin mucus were the core bacterial genera, while Acinetobacter, Pseudomonas and Psychrobacter exhibited differential compositions in gut, skin mucus and water. Conclusions: Representative fresh-, brackish- and seawater samples of hilsa habitats were primarily composed of Vibrio, Serratia and Psychrobacter, and their diversity in seawater was significantly higher (P < 0.05) than freshwater. Overall, salinity and water microbiota had an influence on the microbial composition of hilsa shad, contributing to host metabolism and adaptation processes. This pioneer exploration of hilsa gut and skin mucus bacteria across habitats will advance our insights into microbiome assembly in migratory fish populations. [ABSTRACT FROM AUTHOR]

Background: The host-microbe interactions are complex, dynamic and context-dependent. In this regard, migratory fish species like hilsa shad (Tenualosa ilisha), which migrates from seawater to freshwater for spawning, provides a unique system for investigating the microbiome under an additional change in fish's habitat. This work was undertaken to detect taxonomic variation of microbiome and their function in the migration of hilsa. Methods and results: The study employed 16S rRNA amplicon-based metagenomic analysis to scrutinize bacterial diversity in hilsa gut, skin mucus and water. Thus, a total of 284 operational taxonomic units (OTUs), 9 phyla, 35 orders and 121 genera were identified in all samples. More than 60% of the identified bacteria were Proteobacteria with modest abundance (> 5%) of Firmicutes, Bacteroidetes and Actinobacteria. Leucobacter in gut and Serratia in skin mucus were the core bacterial genera, while Acinetobacter, Pseudomonas and Psychrobacter exhibited differential compositions in gut, skin mucus and water. Conclusions: Representative fresh-, brackish- and seawater samples of hilsa habitats were primarily composed of Vibrio, Serratia and Psychrobacter, and their diversity in seawater was significantly higher (P < 0.05) than freshwater. Overall, salinity and water microbiota had an influence on the microbial composition of hilsa shad, contributing to host metabolism and adaptation processes. This pioneer exploration of hilsa gut and skin mucus bacteria across habitats will advance our insights into microbiome assembly in migratory fish populations. [ABSTRACT FROM AUTHOR]

The hilsa (Tenualosa ilisha) fishery in Myanmar is of importance as it provides an income for around 1.6 million artisanal low-income fisher households and generated USD 237.32M in export earnings from 156,000 metric tons in 2021. Fisheries Performance Indicator assessments have shown that the fishery, both artisanal and industrial, is close to economic collapse. Research was undertaken to find ways to improve the management of the fishery including studies to establish the migration routes and spawning periodicity of hilsa in addition to socioeconomic assessments and business case valuations to recommend finance mechanisms for improved management and maintenance of the fishery. Results indicate that the closed season for hilsa fishing misses the main spawning period in September. In addition, the chemical analysis of hilsa otoliths shows the importance of upstream spawning grounds – some 800km from the sea. Recommendations were made, and enacted March 2022, regarding the need for a new September closed season in addition to no-take hilsa sanctuaries along the main migration routes. A value was placed on the hilsa fishery at close to USD800M per annum. A USD100M annual investment cost is suggested to ensure that the new and old closed seasons are respected by licensed and unlicensed fishers. This investment could be generated by recommended fiscal reforms to provide incentives for fishers to respect the new fishing restrictions. Transboundary fisheries management opportunities are being advanced by informal tripartite scientific collaboration between Bangladesh, India and Myanmar. Social aspects, involving fisheries co-management with artisanal fisher communities and local government authorities, need to be continued to demonstrate the benefits of improved fisheries management in terms of the expected sustainable yields and a move away from potential economic fishery collapse.

Hilsa (Tenualosa ilisha) is a premium table fish in the eastern and some parts of the north-eastern region of India, especially for the Bengali community, contributing uniquely to the societal and economic significance of artisanal fisheries of the country. The major distribution of the fish species in India lies in the Bhagirathi–Hooghly component of the Ganga River system. The aim of the study was to examine if traditional Hilsa fisheries in India are sustainable as the livelihood of artisanal fishers in light of the socio-economic conditions of Hilsa fishers in West Bengal. Structured socio-economic surveys were conducted with 402 fishermen from the upper stretch of river Hooghly to its lower stretch (300 km) in West Bengal during 2020–2021. The average monthly income of the Hilsa fishers in the lower stretch of river Hooghly (Godakhali) (₹25,000–30,000/USD 301–361) was higher than that in the upper stretch at Farakka (₹10,000–15,000/USD 120–180). However, fish species other than Hilsa are generating significantly higher returns for 56% of fishers in the Hooghly district; 40% of Hilsa fishers in South 24 Parganas and Murshidabad (Farakka) districts are engaged in non-fishery activities for livelihood. There are significant differences between Hilsa fishers with other fisheries as secondary occupations and those with non-fishery activities as secondary occupations in terms of socio-economic characteristics. These imply that Hilsa fisheries are profitable as a continued traditional livelihood, but it alone is not sufficient enough to support the livelihood of the artisanal fishers. This indicates the threatened economic sustainability of the Hilsa fisheries sector at present. Considering the high market demand for Hilsa in the eastern and north-eastern regions of India and the market complexities, more significant investments need to be channeled into the Hilsa fisheries of the northern Bay of Bengal region. Such investments encompass a wholesome approach, including more governmental initiatives for conservation and management.

The studied area is the single largest fishery in Bangladesh. The present work was conducted at two points of the Padma River (Sureshwar and Tarabunia) from July 2019 to June 2021 to monitor the efficiency of the 5th Hilsa sanctuary. Proportion of spent rate, length frequency, larvae and Jatka abundance, CPUE of larvae, the length-weight relationship of Jatka, plankton composition, and physico-chemical parameters of water were assessed and found adequate in the Hilsa sanctuary. [ABSTRACT FROM AUTHOR]

Aims The bacterial communities associated with the gastrointestinal (GI) tract are primarily involved in digestion, physiology, and the immune response against pathogenic bacteria for the overall development and health of the host. Hilsa shad (Tenualosa ilisha), a tropical anadromous fish, found predominantly in Bangladesh and India, has so far been poorly investigated for its gut bacterial communities. In this study, both culture-based and metagenomic approaches were used to detect intestinal isolates of hilsa, captured from both freshwater and seawater to investigate the community structure of intestinal microbiota. Methods and results Culture-dependent approach allowed to isolate a total of 23 distinct bacterial species comprising 16 Gram-negative, and 7 Gram-positive isolates, where Proteobacteria and Firmicutes were identified as the two most dominant phyla. While metagenomic approach explored a wide range of important GI bacteria, primarily dominated by Proteobacteria, Firmicutes, and Bacteroidetes, with Proteobacteria and Firmicutes, being the most abundant in freshwater and seawater samples, respectively. Conclusions A combination of these approaches provided the differential GI-associated bacterial diversity in freshwater and seawater hilsa with the prediction of overall functional potential. Impact Statement The study explored the diversity of gut microbiota in hilsa, one of the most preferred nutritious dietary fish, captured from freshwater and seawater habitats, which may encourage to comprehend the composition of the gut microbiome in relation to the migratory behavior and polyunsaturated fatty acid profile of anadromous fish in general. [ABSTRACT FROM AUTHOR]

The exploitation status of Tenualosa ilisha (hilsa) stocks from the riverine and marine region of West Bengal was compared in this study for the first time. The study showed that both the values of exponent and condition factor for hilsa reduced over time when compared with previous studies from the same region. Population dynamics study showed the exploitation rate (E) for the riverine hilsa stock were 0.74, 0.79, and 0.78 during pre-monsoon, monsoon, and post-monsoon, respectively, whereas in marine stock, the values were 0.59, 0.64, and 0.71 during pre-monsoon, monsoon, and post-monsoon indicating higher fishing pressure on the riverine hilsa stock. The riverine fishing mortality rate (F) (pre monsoon, 0.83 year−1; monsoon, 11.1 year−1; post-monsoon, 11.5 year−1) was higher than the marine sector (pre monsoon, 0.33 year−1; monsoon, 0.50 year−1; post-monsoon, 0.41 year−1). The fishery in both these sectors was capturing the first spawners of the hilsa population with a 75% probability. Thus, it was evident that the fishing practice in both the studied regions was unsustainable in nature and the exploitation of hilsa in the riverine part was more intense compared to the marine region. All these changes were causing altered population dynamics and fluctuation in the recruitment pattern of hilsa in West Bengal leading towards the dwindling of annual catch of this species. [ABSTRACT FROM AUTHOR]

This article discusses the progress made in the science and management of the Hilsa shad, a fish species that is widely distributed in the Bay of Bengal and Arabian Sea and supports the livelihoods of millions of people in Bangladesh, India, and Myanmar. The decline of the Hilsa shad is attributed to various factors such as river barriers, reduced river discharges, pollution, overfishing, and climate change. Efforts have been made by researchers from different countries to study the biology, ecology, and aquaculture practices of the species. Regional collaboration and management approaches are needed to conserve the Hilsa shad population. Recent developments in India and Bangladesh have resulted in the re-establishment of the Hilsa fishery in the River Ganga and Gangetic River systems. The article emphasizes the importance of scientific management and regional research efforts for the sustainable production of this important fish species. [Extracted from the article]

For effective fisheries management of Brahmaputra River in Assam, India as well as for sustainable fishery development in the river stretch, it is significant to know the change in pattern of fish landings in previous years. Statistical modelling helps in describing the dynamics of fish landings and their short-term predictions. Thus, we attempted modeling the quarterly data series (1987-2019) on Hilsa (Tenualosa ilisha) landings in the Indian part of Brahmaputra River at Uzanbazar (Guwahati) using univariate forecasting techniques, viz., ARIMA (Auto-Regressive Integrated Moving Average) and NNAR (Neural Network Auto Regression). A comparative performance of fitted models was assessed based on the forecast accuracy measures. Based on comparison of forecast accuracy of models, the ARIMA model outperformed the NNAR model. Based on Akaike Information Criterion (AIC) and Bayesian Information Criterion (BIC) values, an ARIMA(1,0,0)(0,1,1)4 was found to be the appropriate model for describing Hilsa landings of Brahmaputra River. Under the present conditions, the forecasts by fitted ARIMA model predicted stagnation in abundance of prized Hilsa fish in the River at around 3000 kg/year for the upcoming years, which call for formulating and implementing an effective fishery management plan for conservation of its stocks. This is the first attempt on developing time-series models to forecast the Hilsa landings of Brahmaputra River in the region. [ABSTRACT FROM AUTHOR]

Tenualosa ilisha, commonly called Hilsa, is a highly prized species, which has declined in River Brahmaputra, India. The study was carried out for one year and a total of 1,026 individuals were sampled at monthly intervals. In the study, the following growth parameters were observed: asymptotic length (L∞) = 445 mm, growth coefficient (K) = 0.5 year-1, and age at length zero (t0) = -0.5 year-1. Growth performance index (φ) was estimated to be 2.996. Natural mortality rate, total mortality, and fishing mortality was found to be 0.51 year-1, 1.57 year-1, and 1.06 year-1,respectively. Exploitation ratio (E) was found to be 0.675, which indicates that the species is slightly over-exploited. It was seen that length groups that represented the catch in the Indian part of River Brahmaputra comprised fishes of 0–4+ years age. The present study was carried out to assess the population characteristics of this commercially important species from the Indian part of Brahmaputra River, which will contribute towards sustainable fisheries management. [ABSTRACT FROM AUTHOR]

Modification of river flows by dams and barrages has fragmented riverine habitats and threatened the survival of Indian subcontinental river dolphins.In this study, habitat use by endangered Ganges river dolphins in response to dry‐season operations (December‐March) of the Farakka barrage on the Ganga River, located about 20 km upstream of the India–Bangladesh border, was assessed.Ten surveys were conducted in: (i) the Ganga River below the barrage, where rapid changes in water levels were expected owing to barrage operations; (ii) the Farakka feeder canal with stable water levels; and (iii) the Hooghly River downstream of the canal. Dolphin distribution, water depth, fishing boat count and temperature were recorded in all surveys and the data were analysed in a dynamic occupancy modelling framework. Temporal trends in river discharge, primary productivity and fish availability were also estimated to explain river dolphin responses.Occupancy and colonization by dolphins increased in all stretches by spring/March, correlated with rising water temperature and increased fishing intensity, which was related to upstream migration of hilsa fish. In the Ganga River, dolphin occupancy in deep river pools remained stable, but resulted in increased overlap with fisheries as river flow declined. The feeder canal, with stable flows, witnessed increased colonization by dolphins, but also greater risk of bycatch in fishing nets. The canal that appeared as a hydrological refuge thus became an 'ecological trap'.The findings highlight the need for integration of flow maintenance and fishery regulations in the monitoring and management of canals as effective refuges for riverine species. We advocate the inclusion of ecological flow criteria and fishery regulations to reduce dolphin bycatch mortality, in the context of establishing river dolphin conservation plans and transboundary water‐sharing guidelines. The revision of the India–Bangladesh water‐sharing treaty in 2026 could incorporate the above considerations. [ABSTRACT FROM AUTHOR]

Identifying the hormonal signature of gonad maturity and spawning seasonality is essential for upgrading the forecast of recruitment, environmental impacts, and captive maturation. The study evaluated the pattern of gonad development and associated plasma levels of sex steroids and thyroid hormones in both sexes to identify gonadal stage markers and reproductive seasonality in an Indian shad, Tenualosa ilisha. Various stages depicted the cellular organization of ovarian and testicular developments. The ovarian histology revealed hilsa as group synchronous total spawners. The seasonal distribution of distinct maturity stages indicated unsynchronized gonad development within the population. Hilsa exhibited a differential preference of environmental cues in spring and late autumn spawning. However, peak spawning activity took place at similar photoperiod and temperature. The appearance of post-ovulatory follicles (POFs) and late spermiating testicular lobules (LS) marked active spawning in different sexes. The gonadosomatic index (IG) showed temporal, stage-specific variations with a positive correlation with plasma 11-KT (11-ketotestosterone), estradiol (E2) in females or with 17α, 20β-dihydroxy-4-pregnene-3-one (DHP) in males, although the relationship altered temporally for each variable. The positively correlated average plasma 11-KT and E2 values with the number of pre- and post-vitellogenic females serve as hormonal signatures for identifying initiation and completion of gonad growth, respectively. Higher circulating levels of 11-KT compared to T during annual gonad cycles indicate 11-KT as the predominant androgen that controls spermatogenesis in this species. Plasma DHP showed a minor peak in March and a significant elevation in October, synchronized with active spawning in females and males marked as a hormonal signature of spawning irrespective of sex. Plasma T4 showed a positive correlation with IG and spawning females, whereas plasma T3 had a similar correlation with 11-KT and the number of early spermiating males in the population. The results demonstrate hormonal signatures of gonadal recrudescence, maturation, and spawning at the population level for promoting recruitment and artificial propagation of hilsa. [ABSTRACT FROM AUTHOR]

The length-weight relationship (LWR) and relative condition factor are widely used as the most important biological parameters to infer the growth pattern and well-being of fishes. The aim of our study was to investigate the growth parameters of the LWR in different growth phases of Hilsa ( Tenualosa ilisha ), a flagship species of Bangladesh, and compare its relative condition factors across its major habitats. Fish from various rivers in Bangladesh and the Bay of Bengal were sampled, their length-weight growth parameters were measured and subjected to statistical analysis with pooled data from other studies. An isometric growth pattern in Hilsa was predominantly found in the size classes of 25 ≤  TL (total length) < 30, 30 ≤  TL  < 35, and TL  ≥ 40. However, the size class TL  < 25 showed negative allometric growth with the value of the exponent ( b , also known as growth coefficient) between 2.797 and 2.833. The highest weight-growth of Hilsa was within the size class of 35 ≤  TL  < 40, with exponent values of 3.271-3.381 (positive allometric growth) across habitats. Our results revealed that the exponent value varied significantly ( P  < 0.05) between different size classes of Hilsa except between 30 ≤  TL  < 35 and TL  ≥ 40; however, no such significant differences in the exponent values were found across habitats. The Akaike Information Criterion value was lowest for the size-specific length-weight regression model of Hilsa, indicating it was the best-fit model compared to the habitat-specific and pooled sample models. The relative condition factor of Hilsa by habitat was found in the order of Meghna > Bay of Bengal > Andharmanik > Biskhali > Tetulia > Padma. Additionally, the relative physiological well-being of Hilsa from the river Padma and Tetulia was poor compared to that of other habitats. A more in-depth analysis is required to determine the factors that can influence Hilsa's growth and well-being in relation to habitat quality. The present findings have significant relevance for fisheries biologists and managers in understanding and interpreting Hilsa's ecology, relative well-being of populations of same or contrasting habitats, demographic assessment, and for better management of Hilsa in the future., Competing Interests: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (© 2024 The Authors.)

Hilsa shad (Tenualosa ilisha) is one of the most popular and tastiest fishes in Southeast Asia because of its unique soft texture, mouth-watering flavor, high nutritive value with high protein, and very high lipid, attractive body shape, and highly appealing shiny appearance. Recently increased productions of hilsa, in association with high demand but very high price, make it to be a good candidate for value-addition. The major challenge of hilsa value addition lies in its high lipid content, while lipids are the reasons for its unique tastiness. Under a national initiative, the present study therefore developed novel methods to prepare hilsa cube and hilsa powder by stabilizing lipids and proteins, which contained the original taste and flavor of hilsa, and had good storability in freezing and room temperature conditions for 6 months. The pre-spawning, moderate size (600–700g) female hilsa was used for product formulation. Proximate composition, biochemical qualities (TVB-N, TMA-N, pH, PV, TBA value, histamine content) of the hilsa cube and powder were analyzed following standard methods and sensory properties were analyzed using a 5-point hedonic scale. The biochemical parameters and sensory properties of the products varied based on ingredients used and the final product states. Both the products were in good quality for 6 months of storage, since cryoprotectants protected the protein quality both during freezing and high-temperature processing. Carotenoid extract from fresh carrots was found to be effective in reducing lipid oxidation in hilsa. Biochemical attributes in all products gradually decreased with storage time (p < 0.05). Almost similar sensory attributes were observed in both hilsa powder and hilsa cube, which were gradually decreased (p > 0.05) with the progress of the storage period. Both the products were within the acceptable quality limit during all storage periods and conditions. The results suggest that hilsa cube and powder have excellent quality standards, storage stability, and the possibility for fortifying ready-to-eat value-added hilsa products for the consumers at home and aboard.

Bangladesh is rich in fish biodiversity covering interconnected riverine, coastal and marine habitats. Many researchers reported different potentials and threats of biodiversity and suggested measures to minimize the threats. Revival story of hilsa and relevant fish population revealed hopes and ways of sustainable biodiversity management. We attempted to compile the fragmentary fish biodiversity information, described the revival story of hilsa and other important fish along with the threats and challenges of the fish biodiversity and suggested measures for the sustainable management of the fish biodiversity. Freshwater habitats are rich in biodiversity with 265 fresh water fish species. The Meghna River supports the highest 200 fish species as a single river. The marine habitat covers an area of 118,813 km2 that produces 0.66 million tons of fish annually and owned 475 species in 1971, but recent exploration suggests the existence of 394 species. However, the species diversities are increasingly facing threats from direct and indirect anthropogenic activities including juvenile catch, overexploitation, creating obstructions in the migratory routes, pollutions and climate change. Hilsa, the most important species also severely faced these threats and as a result, the production declined to below 0.20 million tons in 2002-2003. Joint efforts of all stakeholders through incentivebased co-management led to the hilsa fishery revival, and its production reached 0.533 million tons in 2019. Along with the hilsa, other interdependent species, especially four important catfish species (Pangasius pangasius, Sperata aor, Bagarius bagarius and Rita rita) have also revived remarkably. Following the lessons learned from the revival of fishery, several management measures focusing on juvenile conservation, protection of broodstock, harmful gear elimination, optimum exploitation, pollution control, incentive-based co-management, habitat protection, restoration and rehabilitation are suggested to ensure maximum sustainable productions and biodiversity conservation focusing on vulnerable and threatened species and improved livelihoods resilience of fishers through good governance. [ABSTRACT FROM AUTHOR]

Hilsa (Tenualosa ilisha) is an amphihaline migratory fish and established itself as one of the most important commercial fishes of the Indo-Pacific region. It has a wide range of distribution and occurs in marine, estuarine and riverine environments. T. ilisha exhibits spawning migration to the freshwater environment of the river systems and thereafter nourish young ones until they return back to sea for maturity. The breeding success of this species depends on the synchronous effects of eco-environmental and biological conditions. The fish normally inhabits the lower regions of the estuaries and the foreshore areas of the sea. Hilsa prefers to reside in the lower basin region of Ganga River during their upstream migration. Several attempts have been made to explore the feeding habit of hilsa in the River system but these are inadequate. Knowledge on the feeding habitat of hilsa and seasonal variation of biotic and abiotic components are very much essential to understand the precise breeding habitat selection of hilsa in monsoon. In the present study, it was found that high turbidity, silica loads, and specific biotic components i.e. diatom population helps upcoming hilsa to spot their preferable breeding ground in the lower basin stretch of Ganga River. Management and conservation of breeding habitat improve the productivity of the fish which is directly benefiting the socio-economy of this fishery. [ABSTRACT FROM AUTHOR]

Exposure to As from drinking water and its impact on the health of the Bangladeshi population has received much attention. However, very little information is available regarding As exposure through consumption of fish, which is the main source of animal protein for the majority of Bangladeshis. In this study, concentrations of As, Cd, Pb, Mn Se and Zn in different types of fish, consumed by Bangladeshis, were determined using Inductively Coupled Plasma Mass Spectrometry. Daily intakes of the toxic elements As, Cd and Pb through fish consumption were estimated to be 31.8, 0.4 and 4.8 μg/day, respectively. Hilsa (Tenualosa ilisha) contained the highest concentrations of total As (mean ± SD was 2.55 ± 1.3 mg/kg; n = 15) among the fish analysed. However, toxic inorganic As species were not detected. The dominant As species in Hilsa fish were: dimethylarsenic acid, arsenobetaine and arsenosugars, at 69, 11 and 20% of total As, respectively. The high concentration of Cd detected in Hilsa eggs (average 278 ± 518 μg/kg; range 7.4–1725 μg/kg; n = 10) is of concern since this may have harmful effects on the development of embryos and lead to a decline in the Hilsa population or the quality of the fish. It can also be harmful to those who consume Hilsa eggs on a regular basis. Selenium was found to be highest in Shoal (Micropterus cataractae) fish and a type of small fish, and lowest in Mrigal (Cirrhinus cirrhosis). Small fish species contained Mn and Zn at 7.1- and 4.3-fold higher concentrations, respectively, compared to big fish species. Keski (Corica soborna), a small fish species, contained by far the highest concentrations of Mn (52 mg/kg) and Zn (140 mg/kg), although the concentration of As (1.4 mg/kg) in this fish was lower than that of several other fish species. Small fish species are often consumed whole, including the bones, and therefore the essential trace elements present are potentially bioavailable for cellular metabolism. Our study shows that the Bangladeshi population can easily meet their daily requirement of Se and Zn from consumption of fish such as Shoal fish (Se and Zn), Hilsa fish (Se and Zn) and Keski fish (Se and Zn). Consumption of small fish (such as Keski) and big fish (such as Hilsa) from Bangladesh can provide valuable sources of essential trace elements as part of a balanced diet and thus negate the need for supplements and biofortification of certain foods. Ours is a small study and a detailed total dietary intake and human biomonitoring studies, that includes coverage of different socio-economic groups, are needed in Bangladesh before giving people supplements or biofortified foods. [ABSTRACT FROM AUTHOR]

Successful captive broodstock development of clupeid fish, hilsa, is one of the major challenges for the artificial propagation of this economically valued fish. The present study provides novel insights into the pond‐reared captive broodstock development of hilsa using artificial feed. In the present study, wild collected hilsa fry (weight 1.35 ± 0.13 g, length 53.84 ± 0.95 mm) were reared in grow‐out ponds for 6 months followed by maintaining them as broodstock in other ponds using formulated feed in both cases. After 6 months of pond rearing, the average body weight and length of fish were 66.76 ± 4.53 g and 184.75 ± 3.65 mm, respectively. In broodstock ponds, hilsa subadults fed with formulated feed (crude protein 41.06%) ensured significant advancement in ovarian maturity with gonado somatic index of 9.09%, enhanced secondary yolk stage oocytes of 91.66% and enlargement of oocyte diameters up to 570 μm. The broodstock reached somatic growth such as average body weight and average body length of 383.80 ± 27.38 g and 339.33 ± 9.68 mm, respectively, with a condition factor of 1.06 ± 0.15. Gut content analysis revealed the better acceptability of the artificial feed. Lipid profiling of muscle and ovary during gonadal maturation revealed mobilization of fat from muscle to ovary and selective retention of some fatty acids (i.e., C14:0, C18:0, C20:5, C22:6 and C20:4) in the ovary, which might help in gonadal maturation. Statement of Significance: Successful rearing of wild‐caught hilsa juvenile in captive condition using formulated feed showed its potential as aquaculture species in low saline conditions.Advance stage of maturation in low saline captive conditions showed the possibility for induced breeding of hilsa, a high priced anadromous fish.Mobilization of fat from muscle to ovary and selective retention of some fatty acids in the ovary showed the scope of dietary manipulation for broodstock development of hilsa. [ABSTRACT FROM AUTHOR]

The complexities surrounding the supply chain logistics for perishable commodities within Bangladesh are extensive. Poor infrastructure, fragmented transportation and corruption compound the operational complexities within this emerging market. This case study analyses many of the day-to-day operational challenges and tensions inherent within Micro-Small-Medium Enterprises (MSMEs) forming the backbone of the Bangladesh socio-economic structure. The drive for transition toward greater levels of sustainability and corporate responsibility is problematic, affecting many levels within an extended and fragmented supply chain. The selected case study highlights the 'lived in' geographical, environmental, economic and cultural factors that impact the ability of emerging market enterprises to remain profitable within emergency scenarios whilst transitioning toward a more sustainable model. This study, whilst detailing many of the tensions and critical issues facing MSMEs, highlights the benefits of direct Government intervention, criticality of a leaner and more efficient supply chain and reassessment of financial incentives to drive the transition to a more efficient and sustainable economy. [ABSTRACT FROM AUTHOR]

Understanding biodiversity and community composition is a prerequisite to sustainable exploitation and conservation of fisheries. We assessed the spatial and seasonal patterns of fish community composition and biodiversity in seasonal no‐take riverine sanctuaries in Bangladesh, which aim to conserve the anadromous hilsa shad (Tenualosa spp. and Hilsa keele). Fish samples were collected during monsoon, as well as pre‐ and postmonsoon, from five sites within two sanctuaries and one site in an open fishing area. Although total abundance was similar along the rivers, species richness was significantly higher at the open fishing site due to its connectivity to nearby habitats. The diversity apparently decreased in a downstream direction. Fish communities at two upstream sites were separated from other sites in multivariate space largely due to higher abundance of hilsa at downstream sites and presence of floodplain‐oriented species at the two upstream sites. Short body length and high trophic level at all sites indicated that fish communities were overexploited. Our results also indicated that riverine hilsa sanctuaries in Bangladesh are rich in fish species diversity and support several threatened species designated by the International Union for Conservation of Nature (IUCN). Our study also suggested that since hilsa abundance shapes community patterns, it can therefore impact riverine ecosystem functioning in the sanctuary areas. The findings of this study can serve as an important baseline for future biodiversity assessment, conservation and impact assessment of conservation in rivers, and therefore help to establish multispecies ecosystem‐based management of riverine fisheries around the world. [ABSTRACT FROM AUTHOR]

In hilsa (Tenualosa ilisha), pseudobranch comprises a row of parallel filaments bear numerous leaf-like lamellae arranged on both sides throughout its length. The purpose of this study was to elucidate involvement of pseudobranchial Na+, K+-ATPase (NKA) 1 α-subunit, and carbonic anhydrase (CA) in concert with H+-ATPase (HAT) compared to their branchial counterparts in freshwater acclimation of hilsa during spawning migration from off-shore of the Bay of Bengal to the Bhagirathi-Hooghly zones of the Ganga river system in India. Adult hilsa fish were collected from seawater (SW), freshwater 1 (FW1), and freshwater 2 (FW2) locations, where the salinity level was 26–28‰, 1–5‰, and 0–0.04‰, respectively. Hilsa migrating through freshwater showed a consistent decrease in the plasma osmolality, sodium (Na+) and chloride (Cl−) ion levels indicates unstable ionic homeostasis. The mRNA expression and activity of NKA 1 α-subunit in pseudobranch as well as in true gills declined with the migration to upstream locations. The pseudobranchial CA activity almost mirrors its branchial counterpart most notably while hilsa entered the freshwater zone, in the upstream river suggesting its diverse role in hypo-osmotic regulatory acclimation. Nevertheless, the H+-ATPase activity of both the tissues increased with the freshwater entry and remained similar during up-river movement into the freshwater environment. The results confirm that the pseudobranchial NKA 1 α-subunit mRNA expression and activity mimic its branchial counterpart in the process of ionoregulatory acclimation during migration through salt barriers. Also, the increase in the activities of pseudobranchial and branchial CA in concert with H+-ATPase (HAT) during freshwater acclimation of hilsa suggests their critical involvement in ion uptake. [ABSTRACT FROM AUTHOR]

Introduction: Fish inhabiting different aquatic habitats adapts to the environment by metabolomic readjustments. Understanding the combined activities of all the metabolic pathways (metabolome) helps in better understanding the complex interactions between gene and environment. Objectives: The anadromous migratory Tenualosa ilisha is a high value food fish comprising the dominant fishery of the rivers Padma and Hooghly. The present study aimed at understanding the influence of the two habitats on the nutritional composition of hilsa. Methods: Metabolite profiling was carried out by GC/MS. De novo assembly of hilsa liver transcriptome was generated under Illumina HiSeq platform and multivariate analysis was employed for correlation and comparison. Results: GC/MS fingerprinting showed C16:0, C18:1, C20:5 and C22:6 to be the predominant fatty acids present in hilsa liver, which were also found to be significantly higher in Hooghly hilsa. Comparative transcriptome analysis revealed that the differentially expressed genes were mainly associated with 'lipid metabolism' and 'amino acid metabolism' pathways. Multivariate analysis between the metabolites amino acid, fatty acid and corresponding gene expression showed that few genes of amino acid metabolism (EZH1, ALAS2 and ALDH4A1) positively correlated with individual amino acids (lysine, glycine and glutamate) in Hooghly hilsa. Similarly, the key genes for LC-PUFA biosynthesis (ELOVL5, FADS2, CPT1) showed positive correlation with individual LC-PUFAs (C18:3, C20:4, C20:5, C22:6), indicating higher LC-PUFA biosynthesis potential in Hooghly hilsa. Conclusion: Comparative metabolomic study in hilsa from the two different habitats showed that the habitats influence the nutritional composition as evidenced by high abundance of amino acids lysine, leucine and arginine and LC-PUFAs C18:3, C20:4, C20:5, C22:6 in Hooghly hilsa. [ABSTRACT FROM AUTHOR]

The population structure of Hilsa Shad (Tenualosa ilisha), a choicest table fish, in the estuaries of India, Bangladesh and Myanmar of Bay of Bengal has been studied by different methods and each provided complementary data on population structure. Considering the present scenario of climate change, increasing pollutant load in Indo--Bangladesh estuarine region and its effect on reproduction and maturation of anadromous Hilsa Shad, a thorough and detailed understanding of the life history of Hilsa is a pre requisite criterion. Results of such studies would be important for sustainable management of this highly economic biological resource. The present paper deals with the aspects of life history and population dynamics of Hilsa Shad in Sundarban estuaries. The data collection was done during the period of June 2011 to March 2012 at Frasergunje Fishing Harbour and offshore of northern Bay of Bengal. The length and weight of total 617 Hilsa fish were measured under this study. Monthly variations of length and weight, length frequency distribution, monthly variation of the allometry coefficient, movement pattern, and catch per unit effort were estimated. The exploitation rate of Hilsa species was found to be 0.78 and the maximum sustainable yield was 11700.18 tonnes whereas the annual catch was 18126.00 tonnes. Highest weight of adult Hilsa was recorded during the monsoon i.e. the months of June, July and August. The result of relative yield per recruitment indicated that the mortality due to current fishing period and pressure were high. Widespread fishing of juvenile and growing Hilsa (< 500 g) declined the Hilsa population considerably losing the economic advantage. The present paper dealt with life history parameters like, growth, exploitation, mortality, stock assessment for sustainable management of Hilsa population. In our study we have observed that Hilsa fish, especially Jatka (<500 gms and <230 mm) is over harvest, from West Bengal coastal areas. [ABSTRACT FROM AUTHOR]

Background: Hilsa shad ( Tenualosa ilisha), a widely distributed migratory fish, contributes substantially to the economy of Bangladesh. The harvest of hilsa from inland waters has been fluctuating due to anthropological and climate change-induced degradation of the riverine habitats. The whole genome sequence of this valuable fish could provide genomic tools for sustainable harvest, conservation and productivity cycle maintenance. Here, we report the first draft genome of T. ilisha from the Bay of Bengal, the largest reservoir of the migratory fish. Methods: A live specimen of T. ilisha was collected from the Bay of Bengal. The whole genome sequencing was performed by the Illumina HiSeqX platform (2 × 150 paired end configuration). We assembled the short reads using SOAPdenovo2 genome assembler and predicted protein coding genes by AUGUSTUS. The completeness of the T. ilisha genome assembly was evaluated by BUSCO (Benchmarking Universal Single Copy Orthologs). We identified single nucleotide polymorphisms (SNPs) by calling them directly from unassembled sequence reads using discoSnp++. Results: We assembled the draft genome of 710.28 Mb having an N50 scaffold length of 64157 bp and GC content of 42.95%. A total of 37,450 protein coding genes were predicted of which 29,339 (78.34%) were annotated with other vertebrate genomes. We also identified 792,939 isolated SNPs with transversion:transition ratio of 1:1.8. The BUSCO evaluation showed 78.1% completeness of this genome. Conclusions: The genomic data generated in this study could be used as a reference to identify genes associated with physiological and ecological adaptations, population connectivity, and migration behaviour of this biologically and economically important anadromous fish species of the Clupeidae family.

De, D.; Kumar, P.; Shyne Anand, P.S.; Biswas, G.; Mukherjee, S.; Ghoshal, T.K.; Suresh, V.R., and Vijayan, K.K., 2019. Embryonic development, larval rearing, and digestive tract and enzyme ontogeny of hilsa shad, Tenualosa ilisha. In: Jithendran, K.P.; Saraswathy, R.; Balasubramanian, C.P.; Kumaraguru Vasagam, K.P.; Jayasankar, V.; Raghavan, R.; Alavandi, S.V., and Vijayan, K.K. (eds.), BRAQCON 2019: World Brackishwater Aquaculture Conference. Journal of Coastal Research, Special Issue No. 86, pp. 73–81. Coconut Creek (Florida), ISSN 0749-0208. Production of fish larvae in captivity and its rearing are the key factors behind the successful mass propagation of any commercial important aquaculture species. Towards this goal, efforts were carried out to standardize fry production and larval rearing of hilsa shad, Tenualosha ilisha. Artificial fertilization of hilsa was done through dry stripping method. Experiments were carried out to understand the embryonic development, larval rearing, ontogenic development of gut and digestive enzymes. Significantly (P <0.01) higher (86.33±0.88%) fertilization and hatching rate (57±0.58%) was recorded when hydration and incubation were done using river water (salinity 0.19 ppt, hardness 950-980 ppm). After an incubation period of 22-24 h at 23±1.0°C temperature, larvae hatched out. Newly hatched larvae measured 2.20±0.23 mm in total length with large yolk sac and 4 to 6 small oil globules. On the 5th day after hatching, the alimentary canal was noticed and the mouth opened between 3rd and 8th days. The aperture of mouth was found to be 82 µm. Larval rearing at different salinity for 15 days revealed the highest survival (53.67±3.75%) when reared at 1.5 ppt. Presence of digestive enzyme (amylase, acidic protease activity, alkaline protease, and lipase) was first detected on 5th - day post-hatching. Fourteen days old larvae were characterized by the absence of oil globule and a well-developed intestine with food particle in the gut. Considering the mouth opening and presence of digestive enzymes on 3rd day and 5th respectively exogenous feeding of suitable particle size may be introduced from 3rd day of hatching onwards. [ABSTRACT FROM AUTHOR]

The morphometric variations between two seasonal migrants (winter and monsoon) of anadromous shad Tenualosa ilisha from Hooghly Estuary were evaluated and compared using geometric morphometrics (GM). Altogether, 128 fish samples of T. ilisha , comprising 64 samples each from winter and the monsoon season, were collected for two successive years (2017 and 2018) and 14 landmarks were digitised uniformly on each individual. Relative warps (RW), principal component analysis (PCA), canonical variate analysis (CVA) and discriminant function analysis (DFA) were used to determine shape variations between seasonal runs. The deformation grid of RW showed that monsoon specimens have a deeper body profile, whereas winter specimens have a slender body profile. The PCA showed low variance (40.45% for first two principal components) and high overlap among all the groups. The CVA-extracted Mahalanobis and Procrustes distances (3.473 and 0.032 respectively) between the two groups (winter and monsoon) were highly significant (P < 0.0001). The DFA also separated two groups with high cross-validated classification rates (85.94 and 95.31% of winter and monsoon specimens respectively were correctly classified). Hence, the results of RW, CVA and DFA clearly indicate the existence of two morphologically distinct units of T. ilisha in Hooghly Estuary. The geometric morphometric method was used to study morphometric variations between two seasonal migrants (monsoon and winter) of anadromous shad Tenualosa ilisha (Hamilton, 1822) from Hooghly Estuary, India. The results of relative warps, canonical variate analysis and discriminant function analysis clearly indicate the presence of two morphologically distinct stocks of T. ilisha migrating towards freshwater through Hooghly Estuary from the marine ecosystem for spawning purposes. [ABSTRACT FROM AUTHOR]

The present study evaluated high pressure processing (HPP) effects on the quality attributes of acid pre-treated hilsa (Tenualosa ilisha) fillets. The acid pre-treatment was done by dipping the dressed fillet in potassium sorbate (0.01%, 0.05% and 0.10% (w/v)) solution for 5 min. Samples were pressurized at 100–300 MPa for 10 min at 30 °C. HPP treatment significantly (P < 0.05) affected the total color difference (Δ E) and textural attributes of acid pre-treated fillets. The HPP treatment significantly (P < 0.05) improved the microbiological quality of fillets. HPP and acid pre-treatment also resulted in lower (P < 0.05) TVB-N and TMA-N values. Free fatty acid contents at higher pressure and higher acid level were significantly (P < 0.05) higher than samples treated at lower pressure level. HPP treatment at lower pressure level improved the acceptability of acid pre-treated fillets in terms of freshness and microbiological properties. • Combined effect of HPP and acid pre-treatment on hilsa fillets resulted in highest antimicrobial activity. • HPP and acid pre-treatment also resulted in lower TVB-N and TMA-N values. • Lipid oxidation (TBA and FFA) was higher at higher HPP levels. • Hardness was higher at higher pressure levels. • HPP (200 MPa) with acid pre-treatment (0.01%) was most suitable to improve microbiological and biochemical properties. [ABSTRACT FROM AUTHOR]

Aims: This study conducted bacterial community, virulence and antibiogram profiling inside the hindgut and skin of freshly caught hilsa fish and those sold at markets. Methods and Results: The results of 16S rRNA‐based high‐throughput sequencing showed a higher number of bacterial genera in marketed fish samples than in fresh fish samples. The total operational taxonomic units, genus counts and diversity index were significantly higher (P > 0·05) in marketed fish, which also had abundant pathogenic bacterial groups. Skin samples had a lower profusion of pathogenic bacteria than gut samples. A total of 52 bacterial isolates from nine species were identified in this study, of which 25 were from a Chittagong market and 22 were from a Dhaka market, whereas only five were from fresh hilsa. The polymerase chain reaction amplification of 12 species‐specific virulence genes in the 52 isolates, namely, aer, hly, chxA, toxB, rtxC, sfa, uge, norB, trx, toxA, ipaH, sigA and coa, indicated a high number of positive samples containing Vibrio cholerae, Aeromonas spp., Klebsiella pneumoniae, Escherichia coli and Staphylococcus aureus. Antibiogram profiling of these bacteria against 10 commercial antibiotics showed high‐resistance patterns of the isolates against sulfamethoxazole, kanamycin, neomycin, ampicillin and tetracycline. Conclusion: The results reveal the spread of multidrug‐resistant bacteria in hilsa fish marketed for human consumption in Bangladesh. Significance and Impact of the Study: This study highlights the risk of spreading environmentally and clinically pathogenic bacteria in fish sold for human consumption in Bangladesh. Such bacteria come from aquatic pollution and poor handling, storage and transportation practices that may predispose fish to major outbreaks of infectious and waterborne diseases. [ABSTRACT FROM AUTHOR]

Myanmar (Burma) is the second largest territory in Southeast Asia with a 2200 km coastline and continental shelf of 230,000 km2. The Myanmar exclusive economic zone (EEZ) occupies 80% of the northeast coastal waters of the Bay of Bengal Large Marine Ecosystem (BoBLME); a 300 km stretch of the Bangladesh coastline completes the area. Four decades ago a combination of extensive mangrove forests, large continental shelf and fertile deposits from the rivers systems discharging into the Bay from two mega deltas (Ganges–Brahmaputra–Meghna and the Ayeyarwady) generated high productivity and valuable coastal fisheries. In terms of productivity, the end of the dry season (April) is the most productive, with 2590 ± 1560 mg C m⁻2 day⁻¹ and high concentrations of chlorophyll a (3.14 ± 2.64 µg L⁻¹). In 2016, the Department of Fisheries (DoF Myanmar) reported marine fishery landings in Myanmar's waters of 2.9 million metric tons (mt), which would have accounted for 47% of the total BoBLME fish catch and 3% of global fisheries coming from 10% of the BoBLME maritime area of 6.2 million km2. Sequential fisheries assessments by Fridtjof Nansen Fisheries Research vessels over four decades have shown that in 2015 a combination of factors has led to reduced yields of valuable fish species by 80% while low value, fast-recruiting fish species have increased. A 2011 Transboundary Diagnostic Analysis (TDA), delivered by the Global Environment Facility (GEF) co-funded FAO implemented BoBLME eight-country project, describes the causes for this dramatic reduction in biomass yields. A Strategic Action Programme (SAP) designed to mitigate the problems was endorsed in 2016 and will be implemented in 2019. The area's coastal fishing fleets are 95% artisanal. There is a combined total of 442 species of fish, prawn, shrimp and lobster in the area. The transboundary hilsa (Tenualosa ilisha) fishery is the most economically important in both Bangladesh and Myanmar. WorldFish and the DoF (Bangladesh and Myanmar) are currently operating hilsa conservation projects in both countries with the International Institute for Environment and Development (IIED) and USAID funded Enhanced Coastal Fisheries in Bangladesh (ECOFISH) projects. A 2018 FAO-WorldFish fisher folk vulnerability and social protection study has demonstrated the precarious nature of coastal fishers. [ABSTRACT FROM AUTHOR]

Hilsa (Tenualosa ilisha) is a clupeid that migrates from the off-shore area through the freshwater river for spawning. The purpose of this study was to investigate the involvement of branchial Na+/K+-ATPase (NKA) and Na+/K+/2Cl− cotransporter (NKCC) in maintaining ionic homeostasis in hilsa while moving across the salt barriers. Hilsa, migrating through marine and brackish waters, did not show any significant decline in NKA activity, plasma osmolality, and plasma ionic concentration. In contrast, all the parameters declined significantly, after the fish reached in freshwater zone of the river. Immunoblotting with NKA α antibody recognized two bands in gill homogenates. The intensity of the higher molecular NKA band decreased, while the other band subsequently increased accompanying the movement of hilsa from marine water (MW) to freshwater. Nevertheless, total NKA expression in marine water did not change prior to freshwater entry. NKCC expression was down-regulated in gill, parallel with NKA activity, as the fish approached to the freshwater stretch of river. The NKA α-1 and NKCC1 protein abundance decreased in freshwater individuals by 40% and 31%, respectively, compared to MW. NKA and NKCC1 were explicitly localized to branchial ionocytes and immunoreactive signal appeared throughout the cytoplasm except for the nucleus and the most apical region indicates a basolateral/tubular distribution. Immunoreactive ionocytes were distributed on the filaments and lamellae; lamellar ionocytes were more in number irrespective of habitat salinity. The decrease in salinity caused a slight reduction in ionocyte number, but not in size and the underlying distribution pattern did not alter. The overall results support previously proposed models that both the ion transporters are involved in maintaining ionic homeostasis and lamellar ionocytes may have the function in hypo-osmoregulation in migrating hilsa, unlike other anadromous teleosts. [ABSTRACT FROM AUTHOR]