The concept of threshold condition factor (Fulton), beyond which more than 50% of the female fish... more The 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 “ready 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 species-specific 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 50 mm 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.
Wetlands are biologically sensitive habitats and envisaged as the most impacted systems by climat... more Wetlands 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.
The concept of threshold condition factor (Fulton), beyond which more than 50% of the female fish... more The 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 “ready 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 species-specific 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 50 mm 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.
Wetlands are biologically sensitive habitats and envisaged as the most impacted systems by climat... more Wetlands 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.
Uploads