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

Not Available

Not AvailableAquatic ecosystems, especially freshwater resources, face many anthropogenic stressors such as pollution, habitat destruction, flow alterations etc leading to impairment in ecological health of the systems. Conservationists need ecological indicators showing the level of alterations or impairment for decision making in managing these important resources. Fish are widely used as sentinel species to evaluate ecological health and are excellent indicators of overall health of aquatic systems they inhabit. This article focuses on briefing some reliable and useful approaches in assessing the ecosystem health in which fishes are used as indicator organism. Many of those approaches need to be refined for each geographical area and type of water body for use as effective biological monitoring tool.Not Availabl

Studies on growth and stock assessment of <i>Saurida undosquamis </i>(Richardson, 1848) from Mumbai coast, India

59-61A study on the age, growth and mortality of Saurida undosquamis (Richardson, 1848) from Mumbai coast was taken up during 2002 to 2004. The asymptotic length (L¥) and growth coefficient (K) were estimated as 346 mm and 0.87 yr-1, respectively. Total, natural and fishing mortalities were 3.48, 1.51 and 1.97 yr-1, respectively. Length at first capture was estimated as 161 mm. Exploitation rate (U) and exploitation ratio (E) were calculated as 0.53 and 0.54 respectively. As the exploitation ratio (E) is slightly beyond the optimum level, there is a need to reduce efforts for the sustainability of resource in future

Studies on growth and stock assessment of Saurida undosqaumis (Richardson, 1848) from Mumbai coast, India

Not AvailableNot AvailableNot Availabl

Interpopulation variation in horse mackerel, Megalaspis cordyla (Linnaeus, 1758), along Indian coast: a chemometric study based on fatty acid profile of heart tissue

1726-1733Populations of Megalaspis cordyla (horse mackerel) from four areas, two each from the east (Digha and Mandapam regions in the Bay of Bengal) and west (Cochin and Mumbai regions of the Arabian Sea) coasts of the Indian peninsula were studied using a chemometric method based on fatty acid composition of their heart tissue. Heart tissue from the specimens from each location was collected and preserved, analyzed by the fatty acid profile method, comprising methanolysis, gas chromatography, and multivariate statistics. The profile showed difference between southern and northern populations in both the coasts. Trend was more obvious in the case of saturated fatty acids and poly unsaturated fatty acids; the southern population with high content of saturated fatty acids and the northern populations with high content of poly unsaturated fatty acids

Not Available

Not AvailableThe study focuses on the estimate of the impact of Covid-19 on inland fisheries resources such as reservoirs and lake. As per the current investigation small, medium and large reservoir fisheries has suffered an economic loss of Rs. 36 million, 4.2 million and 0.31 million respectively. Similarly, backwater fishery of Kerala was also affected with a loss of Rs. 35 million species wise catch composition study in Backwaters indicated huge demand for Lacustrine fishes during lockdown period due to restrictions imposed on the fisheries sector of the state. The government initiatives along with PM Kisan Samman Nidhi Yojana have helped in the revival of the inland fisheries sector post lockdown period.Not Availabl

Not Available

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

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

Not Available

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