Study on Biometric Parameters and Genetic Diversity of Labeo rohita from Harike Wetland-A Ramsar Site

Abstract

Background: Harike wetland (31°08¢ N to 31°23¢ N latitudes and 74°90¢ E to 75°12¢ E longitudes) is an internationally important Ramsar site, supports rare, vulnerable and endangered plants, fish and other faunal species. Weed infestation, pollution and encroachment are considered as important threats of its biota thus time series data with respect to fish diversity, catch composition and genetic variability has an utter importance to interpret changes over time. Cyprinidae family of freshwater fishes includes carps is the largest fish family found in Harike wetland comprising around 50% of total fish composition by weight basis and among carps, Rohu (Labeo rohita) is one of the commercially important food fish species available throughout the year and preferred by consumers. As river Beas and Sutlej, two major rivers of Indus river system confluence at Harike thus possibility of variation within fish stock is very high. With this background present study was carried out to evaluate the fish biodiversity and catch composition of Harike wetland. Study also emphasized on biometrics, length –weight relationship and genetic diversity based on mitochondrial marker genes of commercially important food fish Labeo rohita. Methods: Assessment of fish catch composition and diversity were conducted in landing centre adjacent to Harike wetland through Rapid Fisheries Assessment by Market Survey (RFAMS) technique. Fin tissue samples were collected for genetic diversity analysis of L. rohita by cytochrome oxidase subunit I (COI) gene sequencing, From the fish genomic DNA a partial fragment of approximately 655bp was PCR amplified by FishF1 (5'-TCAACCAACCACAAAGACATTGGCAC-3') and FishR1 (5'-TCGACTAATCATAAAGATATCGGC AC-3') primer pair. Calculation of intraspecific mean and pairwise distances was performed by MEGA 6.0 software using the K2P parameters Results: Total 30 species of fishes were recorded from Harike wetland and these belong to 14 families and 21 genera. In L. rohita average weight (Wt), total length (TL), standard length (SL) and forked length (FL) were recorded 2600±5.64g (1700-3600 g), 58.2±5.65 cm (51.3-67.6cm), 48.0±8.54 cm (42.5-55.5cm) and 46.0±0.25 cm (38.0-54.5cm), respectively. Biometric study revealed that sufficient numbers of mature L. rohita are available in wetland. L. rohita established negative algometric growth (b= 2.701); thus species became slender as it increased in length. The pairwise distances ranged from 0.00 to 18.49% with a mean ±S.E value of 4.70%±0.40. Total of 9 haplotypes were observed in L. rohita COI sequences. The diversity in haplotype and nucletide values were observed 0.848 and 0.024, respectively. The present study states that L. rohita stocks in Harike wetland are genetically diverse.