Baseline information of reproduction parameters of an amphidromous croaker Johnius coitor (Hamilton, 1822) from Ganga river basin, India with special reference to potential influence of climatic variability

Reproductive biology of female amphidromous croaker Johnius coitor (Hamilton, 1822) was studied for the first time from various freshwater stretches of Ganga river basin, India in relation to climatic variability. The species showed high spatial variation in reproductive phenology and capable of breeding during pre-monsoon, monsoon, post-monsoon and winter. Water temperature is the most crucial environmental parameter influencing gonadal maturation and breeding. Generalized additive model (GAM) models revealed water temperature near 23–25 °C as optimum and threshold GSI above 3 units necessary for breeding. Pre-spawning fitness (Kspawn50) and size at 50% maturity (LM50) benchmarked through Kaplan-Meier survival fit estimates were in the range 1.27–1.37 units and 19–24.5 cm respectively. First maturity of females was encountered at 11.4 cm within the size range 7.2–28.5 cm. Egg parameters in mature-ripe females ranged between 0.29–0.80 mm (diameter), 0.05–0.19 mg (weight) and 5687–121 849 eggs (absolute fecundity). Mapping of climate preferendum through LOESS smoothing technique hinted water temperatures 32 °C to be detrimental for attainment of pre-spawning fitness while no dependence on rainfall was observed. Based on the climato-hydrological influence on breeding and regional trends of changing climate along river Ganga, we infer minimal climate driven changes in breeding phenology of this amphidromous fish species. Results of this study may serve as baseline information for future studies assessing climate driven changes and evolutionary adaptations in croakers from river Ganga

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Not AvailableFloodplain wetlands are considered as biologically sensitive habitats and predicted to be the most impacted through climate change. They form an important fishery resource in West Bengal, India. Analysis of Indian Meteorological Department (IMD) derived climatic data has revealed a unanimous warming trend (0.18–0.28 C) and decreasing rainfall (135.6–257 mm) among the studied districts (North 24 Parganas, Nadia and Kolkata) of West Bengal over the last three decades. Four floodplain wetlands under cooperative fisheries management were studied during February 2015 and December 2015. Data were collected through a structured communication process involving multiple interviews through multiple rounds of surveys and also from secondary sources. Six climate smart fishery strategies could be identified, namely Temporary pre-summer enclosure, Submerged branch pile (Kata) refuge, Autumn stocking, Torch light fishing, Deep pool (Komor) refuge and Floating aquatic macrophyte refuge fishery (Pana chapa). Few of them are capable of serving as conservation tools by providing refuge during summer or water stress and maintaining base stocks in the wetlands for recruitment in the following monsoon season. The present paper discusses the climate smart nature of these pre-existing indigenous fishery strategies. These strategies need to be optimized and may be used for adoption of sustainable climate smart fisheries management in floodplain wetlandsFloodplain wetlands are considered as biologically sensitive habitats and predicted to be the most impacted through climate change. They form an important fishery resource in West Bengal, India. Analysis of Indian Meteorological Department (IMD) derived climatic data has revealed a unanimous warming trend (0.18–0.28 C) and decreasing rainfall (135.6–257 mm) among the studied districts (North 24 Parganas, Nadia and Kolkata) of West Bengal over the last three decades. Four floodplain wetlands under cooperative fisheries management were studied during February 2015 and December 2015. Data were collected through a structured communication process involving multiple interviews through multiple rounds of surveys and also from secondary sources. Six climate smart fishery strategies could be identified, namely Temporary pre-summer enclosure, Submerged branch pile (Kata) refuge, Autumn stocking, Torch light fishing, Deep pool (Komor) refuge and Floating aquatic macrophyte refuge fishery (Pana chapa). Few of them are capable of serving as conservation tools by providing refuge during summer or water stress and maintaining base stocks in the wetlands for recruitment in the following monsoon season. The present paper discusses the climate smart nature of these pre-existing indigenous fishery strategies. These strategies need to be optimized and may be used for adoption of sustainable climate smart fisheries management in floodplain wetlandsNot Availabl

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Not AvailableWetlands are biologically sensitive habitats and envisaged as the most impacted systems by climate change. Floodplain wetlands of West Bengal, India, are important fisheries resources and provide tremendous economic and ecological services. There is lack of long-term quantified data to assess the impacts of climate change on floodplain wetlands fisheries in India. The article presents a stakeholder-driven approach to quantify the impacts of climate change on wetland fisheries. A modified Delphi method has been used to accomplish this. The present article discusses the modified methodology and the results obtained thereof. The study identified around seven potential climate change-induced threats on wetland fisheries among which water stress (95% consensus), wetland accretion/sedimentation (85%), aquatic weed proliferation (70%) and loss of wetland connectivity (65%) are high-priority issues demanding immediate management action. These issues are expected to further aggravate in future climatic scenario.Not Availabl

Data_Sheet_1_Hilsa fisheries in India: a socio-economic analysis of fishers in deltaic Ganga region of river Hooghly.PDF

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.</p

Baseline information of reproduction parameters of an amphidromous croaker

Reproductive biology of female amphidromous croaker Johnius coitor (Hamilton, 1822) was studied for the first time from various freshwater stretches of Ganga river basin, India in relation to climatic variability. The species showed high spatial variation in reproductive phenology and capable of breeding during pre-monsoon, monsoon, post-monsoon and winter. Water temperature is the most crucial environmental parameter influencing gonadal maturation and breeding. Generalized additive model (GAM) models revealed water temperature near 23–25 °C as optimum and threshold GSI above 3 units necessary for breeding. Pre-spawning fitness (Kspawn50) and size at 50% maturity (LM50) benchmarked through Kaplan-Meier survival fit estimates were in the range 1.27–1.37 units and 19–24.5 cm respectively. First maturity of females was encountered at 11.4 cm within the size range 7.2–28.5 cm. Egg parameters in mature-ripe females ranged between 0.29–0.80 mm (diameter), 0.05–0.19 mg (weight) and 5687–121 849 eggs (absolute fecundity). Mapping of climate preferendum through LOESS smoothing technique hinted water temperatures 32 °C to be detrimental for attainment of pre-spawning fitness while no dependence on rainfall was observed. Based on the climato-hydrological influence on breeding and regional trends of changing climate along river Ganga, we infer minimal climate driven changes in breeding phenology of this amphidromous fish species. Results of this study may serve as baseline information for future studies assessing climate driven changes and evolutionary adaptations in croakers from river Ganga

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Not AvailableThe concept of threshold condition factor (Fulton), beyond which more than 50% of the female fish population may attain readiness for spawning coined as pre-spawning fitness (Kspawn50), has been proposed in the present article and has been estimated by applying the non-parametric Kaplan-Meier method for fitting survival function. A binary coding strategy of gonadal maturity stages was used to classify whether a female fish is Bready to spawn^ or not. The proposed Kspawn50 has been generated for female Mystus tengara (1.13–1.21 units), M. cavasius (0.846–0.945 units), and Eutropiichthys vacha (0.716–0.799 units). Information on the range of egg parameters (fecundity, egg weight, egg diameter) expected at the pre-spawning stage was also generated. Additional information on speciesspecific thermal and precipitation window (climate preferendum) within which Kspawn50 is attained was also generated through the LOESS smoothing technique. Water temperatures between 31 and 36 °C (M. tengara), 30 and 32 °C (M. cavasius), and 29.5 and 31 °C (E. vacha) and monthly rainfall between 200 and 325 mm (M. tengara), > 250 mm (M. cavasius), and around 50mm and between 350 and 850 mm(E. vacha) were found to be optimum for attainment of Kspawn50. The importance of parameterization and benchmarking of Kspawn50 in addition to other conventional reproductive biology parameters has been discussed in the present article. The purposes of the present study were fulfilled by generating baseline information and similar information may be generated for other species replicating the innovative methodology used in this study.ICAR and NICR

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Not AvailableTemperature and seasonal rainfall along with other environmental variables are important in regulating the reproductive cycles in teleost fishes. Certain environmental variables may act as cues for reproduction and changes in these may affect seasonality and success of reproduction, as fishes are known to integrate their physiological functions with environmental cycles. Wetlands are sensitive to climate change due to their shallow and confined nature. Since wetlands are important spawning and nursery grounds for many fishes, changes in the environmental variables may have direct consequences for the spawning and survival of fish. In the present study, we have assessed climatic and water chemistry variables capable of influencing seasonality in environmental variables as well as gonadal maturation of spotted snakehead Channa punctata, to predict threshold values of Gonado Somatic Index in females and a favourable range of identified climatic and water chemistry variables for breeding success. Among the climatic and water chemistry variables studied, seasonal variation in rainfall was found to have the most profound effect on gonadal maturation and breeding in C. punctata, followed by water temperature. The favourable range of rainfall obtained varied between 800 mm to 1400 mm, corresponding to thewater temperature range between 29 °C and 31 °C. An overall significant warming trend with a reduction in total rainfall has been observed with changes in seasonal trends in temperature and rainfall in the study area. The rainfall being the major climatic factors influencing water chemistry in the wetlands during the spawning season, changes in rainfall pattern may influence breeding periodicity of C. punctata in wetlands in climate change scenario.ICAR and NICR

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Not AvailableThe concept of threshold condition factor (Fulton), beyond which more than 50% of the female fish population may attain readiness for spawning coined as pre-spawning fitness (Kspawn50), has been proposed in the present article and has been estimated by applying the non-parametric Kaplan-Meier method for fitting survival function. A binary coding strategy of gonadal maturity stages was used to classify whether a female fish is Bready to spawn^ or not. The proposed Kspawn50 has been generated for female Mystus tengara (1.13–1.21 units), M. cavasius (0.846–0.945 units), and Eutropiichthys vacha (0.716–0.799 units). Information on the range of egg parameters (fecundity, egg weight, egg diameter) expected at the pre-spawning stage was also generated. Additional information on speciesspecific thermal and precipitation window (climate preferendum) within which Kspawn50 is attained was also generated through the LOESS smoothing technique. Water temperatures between 31 and 36 °C (M. tengara), 30 and 32 °C (M. cavasius), and 29.5 and 31 °C (E. vacha) and monthly rainfall between 200 and 325 mm (M. tengara), > 250 mm (M. cavasius), and around 50mm and between 350 and 850 mm(E. vacha) were found to be optimum for attainment of Kspawn50. The importance of parameterization and benchmarking of Kspawn50 in addition to other conventional reproductive biology parameters has been discussed in the present article. The purposes of the present study were fulfilled by generating baseline information and similar information may be generated for other species replicating the innovative methodology used in this study.Not Availabl

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Not AvailableReproductive biology of female amphidromous croaker Johnius coitor (Hamilton, 1822) was studied for the first time from various freshwater stretches of Ganga river basin, India in relation to climatic variability. The species showed high spatial variation in reproductive phenology and capable of breeding during pre-monsoon, monsoon, post-monsoon and winter. Water temperature is the most crucial environmental parameter influencing gonadal maturation and breeding. Generalized additive model (GAM) models revealed water temperature near 23–25 °C as optimum and threshold GSI above 3 units necessary for breeding. Pre-spawning fitness (Kspawn50) and size at 50% maturity (LM50) benchmarked through Kaplan- Meier survival fit estimates were in the range 1.27–1.37 units and 19–24.5 cm respectively. First maturity of females was encountered at 11.4 cm within the size range 7.2–28.5 cm. Egg parameters in mature-ripe females ranged between 0.29–0.80mm(diameter), 0.05–0.19 mg (weight) and 5687–121 849 eggs (absolute fecundity). Mapping of climate preferendum through LOESS smoothing technique hinted water temperatures 32 °C to be detrimental for attainment of pre-spawning fitness while no dependence on rainfall was observed. Based on the climato-hydrological influence on breeding and regional trends of changing climate along river Ganga, we infer minimal climate driven changes in breeding phenology of this amphidromous fish species. Results of this study may serve as baseline information for future studies assessing climate driven changes and evolutionary adaptations in croakers from river Ganga.Indian Council of Agricultural Research (ICAR) and National Innovations in Climate Resilient Agriculture (NICRA