Dr. Laskar | Zoological Survey of India (original) (raw)
Phone: +919957796487
Address: department of Biotechnology, Assam (Central) University, Silchar, Cachar, Assam, India
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Understanding the sexual dimorphism in fish is an uphill task and is paradoxical in different spe... more Understanding the sexual dimorphism in fish is an uphill task and is paradoxical in different species. In general, the studies on the biometrics of fish form the basis of fishery investigations particularly in the management and exploitation of fishery resources. The present study was carried in order to obtain characteristic relationship of various morphological parameters between the sexes of Neolissochilus hexagonolepis (McClelland). Considerable differences in the percentage of some morphometric characters on standard length have been observed between males and females. The males were found to have greater head width at operculum, snout length, predorsal length and preanal length than the females. On the other hand, the females had greater body depth at dorsal fin insertion, pectoral fin length, anal fin height and ventral fin height than the males. The males were found to have greater value of biometric index for body depth at dorsal fin insertion, pectoral fin length, anal fin height and height of ventral fin than the females; while the females had greater values for head width at operculum, snout length, predorsal length and preanal length. The variation in the biometric index and percentage of anal fin height on standard length was highly significant between males and females. Together the values of correlation coefficient 'r' between the variable characters and the standard length were found positive, with the highest value of regression coefficient 'b' in case of total length (b=1.3082) and lowest in case of head height at eye (b=0.0366).
The Digital Elevation Model (DEM) can precisely represent hydro-geomorphological parameters for f... more The Digital Elevation Model (DEM) can precisely represent hydro-geomorphological parameters for fish habitat inventory. The GIS technique equipped by Spatial Multi-Criteria Evaluation (SMCE) model helps in processing the selected parameters for fish habitat suitability mapping. In the present work DEM of the Shuttle Radar Topographic Mission (SRTM) using Interferometric Synthetic Aperture Radar (InSAR) technique is used for parameter inventory of the fish habitat in lotic system. Arunachal Pradesh (Eastern Himalaya) in the North-East region of India has been selected for this exercise. Information like stream network, stream slope, stream elevation and stream length are derived from SRTM DEM. The stream lengths under each category of stream slope and stream elevation are analysed. The state Arunachal Pradesh with total area of 83743 km 2 has 29003.23 km of river length, distributed in the range of 0˚ to 40˚ gradients and 107 m to 5699 m elevations. Since the studied parameters fluctuate between wide ranges, there is high variation in habitat characters as well as probability of species speciation and thereby diversification. The total stream length under suitable category is 62.69%, moderately suitable 21.42% and less suitable 15.89%. This study of fish habitat using geomorphological and hydrological parameters may be termed as ICHTHYOGEOMORPHOLOGY.
One hundred thirty eight fish species were collected during a systematic survey of 35 rivers in A... more One hundred thirty eight fish species were collected during a systematic survey of 35 rivers in Arunachal Pradesh state, India, in March 2004 to March 2008. Based on this survey and on literature review we developed a checklist with 213 fish species for the state. We have added 43 species to the previous record of 170 species. This study confirmed the occurrence of five new species described by previous investigations and encompasses the discovery of two new species, although the taxonomic status of 27 species is uncertain and requires additional study.
Background: The taxonomic validity of Northeast Indian endemic Mahseer species, Tor progeneius an... more Background: The taxonomic validity of Northeast Indian endemic Mahseer species, Tor progeneius and Neolissochilus hexastichus, has been argued repeatedly. This is mainly due to disagreements in recognizing the species based on morphological characters. Consequently, both the species have been concealed for many decades. DNA barcoding has become a promising and an independent technique for accurate species level identification. Therefore, utilization of such technique in association with the traditional morphotaxonomic description can resolve the species dilemma of this important group of sport fishes.
Background: Catfishes are globally demanded as human food, angling sport and aquariums keeping th... more Background: Catfishes are globally demanded as human food, angling sport and aquariums keeping thus are highly exploited all over the world. North-East India possess high abundance of catfishes and are equally exploited through decades. The strategies for conservation necessitate understanding the actual species composition, which is hampered due to sporadic descriptions of the species through traditional taxonomy. Therefore, actual catfish diversity in this region is important to be studied through the combined approach of morphological and molecular technique of DNA barcoding.
Understanding the sexual dimorphism in fish is an uphill task and is paradoxical in different spe... more Understanding the sexual dimorphism in fish is an uphill task and is paradoxical in different species. In general, the studies on the biometrics of fish form the basis of fishery investigations particularly in the management and exploitation of fishery resources. The present study was carried in order to obtain characteristic relationship of various morphological parameters between the sexes of Neolissochilus hexagonolepis (McClelland). Considerable differences in the percentage of some morphometric characters on standard length have been observed between males and females. The males were found to have greater head width at operculum, snout length, predorsal length and preanal length than the females. On the other hand, the females had greater body depth at dorsal fin insertion, pectoral fin length, anal fin height and ventral fin height than the males. The males were found to have greater value of biometric index for body depth at dorsal fin insertion, pectoral fin length, anal fin height and height of ventral fin than the females; while the females had greater values for head width at operculum, snout length, predorsal length and preanal length. The variation in the biometric index and percentage of anal fin height on standard length was highly significant between males and females. Together the values of correlation coefficient 'r' between the variable characters and the standard length were found positive, with the highest value of regression coefficient 'b' in case of total length (b=1.3082) and lowest in case of head height at eye (b=0.0366).
The Digital Elevation Model (DEM) can precisely represent hydro-geomorphological parameters for f... more The Digital Elevation Model (DEM) can precisely represent hydro-geomorphological parameters for fish habitat inventory. The GIS technique equipped by Spatial Multi-Criteria Evaluation (SMCE) model helps in processing the selected parameters for fish habitat suitability mapping. In the present work DEM of the Shuttle Radar Topographic Mission (SRTM) using Interferometric Synthetic Aperture Radar (InSAR) technique is used for parameter inventory of the fish habitat in lotic system. Arunachal Pradesh (Eastern Himalaya) in the North-East region of India has been selected for this exercise. Information like stream network, stream slope, stream elevation and stream length are derived from SRTM DEM. The stream lengths under each category of stream slope and stream elevation are analysed. The state Arunachal Pradesh with total area of 83743 km 2 has 29003.23 km of river length, distributed in the range of 0˚ to 40˚ gradients and 107 m to 5699 m elevations. Since the studied parameters fluctuate between wide ranges, there is high variation in habitat characters as well as probability of species speciation and thereby diversification. The total stream length under suitable category is 62.69%, moderately suitable 21.42% and less suitable 15.89%. This study of fish habitat using geomorphological and hydrological parameters may be termed as ICHTHYOGEOMORPHOLOGY.
One hundred thirty eight fish species were collected during a systematic survey of 35 rivers in A... more One hundred thirty eight fish species were collected during a systematic survey of 35 rivers in Arunachal Pradesh state, India, in March 2004 to March 2008. Based on this survey and on literature review we developed a checklist with 213 fish species for the state. We have added 43 species to the previous record of 170 species. This study confirmed the occurrence of five new species described by previous investigations and encompasses the discovery of two new species, although the taxonomic status of 27 species is uncertain and requires additional study.
Background: The taxonomic validity of Northeast Indian endemic Mahseer species, Tor progeneius an... more Background: The taxonomic validity of Northeast Indian endemic Mahseer species, Tor progeneius and Neolissochilus hexastichus, has been argued repeatedly. This is mainly due to disagreements in recognizing the species based on morphological characters. Consequently, both the species have been concealed for many decades. DNA barcoding has become a promising and an independent technique for accurate species level identification. Therefore, utilization of such technique in association with the traditional morphotaxonomic description can resolve the species dilemma of this important group of sport fishes.
Background: Catfishes are globally demanded as human food, angling sport and aquariums keeping th... more Background: Catfishes are globally demanded as human food, angling sport and aquariums keeping thus are highly exploited all over the world. North-East India possess high abundance of catfishes and are equally exploited through decades. The strategies for conservation necessitate understanding the actual species composition, which is hampered due to sporadic descriptions of the species through traditional taxonomy. Therefore, actual catfish diversity in this region is important to be studied through the combined approach of morphological and molecular technique of DNA barcoding.