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

Environmental parameters and stocking density influence growth, feed utilization and economics of butter catfish, Ompok bimaculatus (Bloch, 1794) production in floating net cages in a large tropical reservoir, India

Not AvailableAn experiment was conducted to study the influence of environmental parameters and stocking density on growth, survival, feed utilization, and economic feasibility of a high value butter catfish, Ompok bimaculatus in floating cages in a large tropical reservoir of India for 180 days. The fingerlings (11.44 ? 1.33 cm; 8.05 ? 3.27 g) were stocked at three stocking densities, viz., 15, 25 and 35 fingerlings m-3 in GI cages (32m3) in triplicates. Commercial floating pellets were fed to fish at 5?3% of fish biomass. The results indicated that the fishes at the lowest stocking density of 15 fingerlings m-3 had significantly higher (p 0.05) between stocking densities of 15 fingerlings m-3 and 25 fingerlings m-3. The condition factor was insignificantly higher at lower densities and its values close to 1 indicated congeniality of reservoir ecosystem for cage culture of the species. The coefficient of variation of weight was significantly higher (24.19 ? 1.20) at 35 fingerlings m-3. The highest economic gains in terms of benefit cost ratio (1.77) were achieved at the lowest stocking density. The present study indicated better growth and economic returns at lower stocking densities of 15?25 fingerlings m-3. The nutrient load and plankton abundance were higher at culture site, however, did not vary significantly from reference sites throughout the culture period. Although most of the environmental parameters showed significant seasonal variations, dissolved oxygen showed significant positive relation (r = 0.86) with the growth of the fish. This is the first study reporting feasibility of cage culture of this highly renumerative species in open waters. The cage culture of this species will not only ensure better economic returns to the marginal cage farmers but will aid in the conservation of this species in natural ecosystem. Being a low volume high value species, the impact on environment will be less compared with high volume low value species. This study will serve as baseline for standardization of its grow-out protocol in cages and will be a step towards much needed species diversification for sustainable small scale cage farming in tropical reservoirs of Asia

Impact of stocking density on growth, feed utilization and survival of cage reared minor carp, Labeo bata (Hamilton, 1822) in Maithon reservoir, India

Not AvailableThe present study was carried out to evaluate the effects of stocking density on growth performance of stunted fingerlings of Labeo bata in cages for a period of 180 days, at Maithon reservoir, Jharkhand, India. L. bata (8.80 + 0.67 cm; 6.18 ? 1.32 g) were reared at three stocking densities of 50 fingerlings m?3, 75 fingerlings m?3, and 100 fingerlings m??3 in triplicates in Galvanized Iron (GI) cages. Fishes were fed with floating pelleted feed (CP: 32%, CL: 4%) @ 5?3% of the body weight twice a day. L. bata reared at density of 50 fingerlings m?3 showed significantly higher (p 0.05) in SGR were found between the densities 75 fingerlings m?3 and 100 fingerlings m?3. The growth and survival were lowest at stocking density of 100 fingerlings m?3. Feed conversion ratio (FCR) and protein efficiency ratio (PER) were highest i.e. 1.95 ? 0.08 and 1.65 ? 0.06 respectively at 50 fingerlings m?3. Condition factor (K) varied significantly (p 0.05) among the treatments. Length weight relationship exhibited positive allometric growth of L. bata in cages. In spite of higher biomass produced at higher densities, the benefit cost ratio (BCR) was highest at stocking density of 50 fingerlings m?3 (1.57). Overall, our results indicate that L. bata exhibit better growth and condition at lower stocking density indicating that higher densities negatively affect the growth. The fish in cages exhibited growth comparable to ponds and open waters. It can be concluded that the stocking density of 50 fingerlings m?3 is the most desirable and economic for L. bata fingerlings to achieve table size in the cage culture system

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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

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Not AvailableThe present study investigates the success of stocking fingerlings of Indian major carps -Gibelion catla (Hamilton), Labeo rohita Hamilton and Cirrhinus mrigala Hamilton – to enhance fish yield in 58 small reservoirs in Odisha State, India. Fish stocking and yield data were collected from State Fisheries Department, Odisha. The relationships between area, stocking density and fish yield of different size groups of reservoirs were assessed using the Pearson correlation coefficient (r). Fish yield increased significantly (p < 0.05, t-test) from 204 kg/ha/year in 2012–13 to 323 kg/ ha/year in 2013–14 due to adoption of CBF. The corresponding per capita fish production increased from 398 kg fisher−1 year−1 to 702 kg fisher−1 year−1 benefitting more than 8,000 fisher households. Reservoirs in the size group 100–500 ha showed the highest response of fish yield with respect to stocking of fingerlings. The size of fingerlings at stocking and area of the reservoir had greater impact on enhancing fish yield. Stocking had a profound positive impact on fish yield. This study forms a baseline evaluation of the impact of stocking on small tropical reservoirs in India. It also recommends management measures and discusses issues, and the way forward for sustainable fisheries enhancement in small tropical reservoirs in eastern India.Not Availabl

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Not AvailableThe present study was carried out to evaluate the effects of stocking density on growth performance of stunted fingerlings of Labeo bata in cages for a period of 180 days, at Maithon reservoir, Jharkhand, India. L. bata (8.80 + 0.67 cm; 6.18 ± 1.32 g) were reared at three stocking densities of 50 fingerlings m 3, 75 fingerlings m 3, and 100 fingerlings m- 3 in triplicates in Galvanized Iron (GI) cages. Fishes were fed with floating pelleted feed (CP: 32%, CL: 4%) @ 5–3% of the body weight twice a day. L. bata reared at density of 50 fingerlings m 3 showed significantly higher (p < 0.05) specific growth rate (SGR) (1.08 ± 0.02) and survival (84%) than those reared at 75 fingerlings m 3 and 100 fingerlings m 3. No significant differences (p > 0.05) in SGR were found between the densities 75 fingerlings m 3 and 100 fingerlings m 3. The growth and survival were lowest at stocking density of 100 fingerlings m 3. Feed conversion ratio (FCR) and protein efficiency ratio (PER) were highest i.e. 1.95 ± 0.08 and 1.65 ± 0.06 respectively at 50 fingerlings m 3. Condition factor (K) varied significantly (p < 0.05) among the treatments and was significantly better at 50 fingerlings m 3 after 180 days. Coefficient of variation (CV) was lowest at 50 fingerlings m 3, but did not vary significantly (p > 0.05) among the treatments. Length weight relationship exhibited positive allometric growth of L. bata in cages. In spite of higher biomass produced at higher densities, the benefit cost ratio (BCR) was highest at stocking density of 50 fingerlings m 3 (1.57). Overall, our results indicate that L. bata exhibit better growth and condition at lower stocking density indicating that higher densities negatively affect the growth. The fish in cages exhibited growth comparable to ponds and open waters. It can be concluded that the stocking density of 50 fingerlings m 3 is the most desirable and economic for L. bata fingerlings to achieve table size in the cage culture system.Not Availabl

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Not AvailableFloodplain wetlands are among the most threatened ecosystems. It is highly vulnerable to climate change, affecting the wetland ecosystem and its associated fisheries. In the face of data deficiency, this article presents an alternative approach to assess the vulnerability of wetland fisheries to climate change. A total of 15 wetlands from a wetland-fisheries-rich area of West Bengal, India, were selected to illustrate the methodology. The proposed method mainly relies on stakeholders’ perceptions of the wetland fisheries vulnerability. Elicitation stakeholders’ response iteratively screened the indicators of fisheries vulnerability. The hybrid method of index-based vulnerability comprises two types of indicators: climate indicators with long-term quantitative data and stakeholder perceived vulnerability indicators specific to wetland fisheries. The high level of consensus (92%) among respondents provided strong evidence of climate change in last 15 years, which has also been validated through long-term data analysis. The Principal Component Analysis extracted five synthesized vulnerability indicators, explaining 83.35% variability of the original 14 indicators. The wetlands were further grouped according to differential vulnerability for prioritizing the wetlands for strategic planning. Climate change, reduction in species richness and adaptive capacity were the key components responsible for differential vulnerability. The study also revealed some indigenous climate-smart mitigation strategies of wetland fisheries to climate change.Not Availabl

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Not AvailableThe present study assessed the impact of fingerling stocking of Indian major carps (Gibelion catla, Labeo rohita, and Cirrhinus mrigala) on fish yield in 24 small reservoirs of Central India. The time series data on fish stocking and yield were collected from the State Fisheries Department, Govt. of Chhattisgarh, for the year 2008 to 2016. The fish yield increased significantly (p < 0.05) from 87.11 to 379.13 kg/ha/year due to stocking indicating significant impact on fish production. The relationships between area, stocking density, and fish yield of reservoirs were also assessed. Stocking had a significant positive impact on fish yield (t test, p < 0.05). The important water quality parameters were also studied to have a conspicuous picture of eco-hydrological characteristics of these selected small reservoirs. The study forms a baseline for the small tropical reservoir fisheries of Central India (Chhattisgarh state) and suggests regional strategies for sustainable fisheries enhancement and management, employment gen eration, and nutritional security of a large number of fish-eating population.Not Availabl

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