Tor mahseer, Tor tor (Hamilton, 1822), is an economically important food and sport fish, native of trans-Himalayan region  and also a promising candidate species for aquaculture . It is a potamodromous cyprinid species, found in fast-running rivers and streams with rocky bottoms in Nepal, Bangladesh, India, Bhutan and Pakistan . In India, T. tor is known from the Ganga (including sub-Himalayan range), Indus, Brahmaputra and Narmada river systems . However, Lal et al.  illustrated the extended distribution of T. tor in the peninsular rivers, Godavari and Krishna.
In current years, the wild population of T. tor is reported to have declined, as it has been facing numerous challenges in its natural range including overfishing, pollution, habitat degradation, hydropower development, anthropogenic pressure and climate change . As a consequence, it was accredited a status of Endangered species in 2015 , however currently, the species is assessed as data deficient under IUCN, 2018  due to ambiguity in taxonomic identification  and distribution .
Prior information about genetic variability and stock structure is prerequisite for conservation and stock improvement of any species which have undergone decline in its population, in order to avoid population crashes and ensure resource sustainability.
The faster evolutionary rate and maternal inheritance make mitochondrial DNA a potential genetic marker for analyzing intra specific variability as well as phylogenetic studies. Mitochondrial genes, like, cyt b and ATPase6/8 have been used as markers for population level studies in various fish species . Still, there is a limited knowledge about genetic diversity in T. tor, restricted to a very few studies. Pasi et al. (2013)  employed, cyt b (967 bp) to reveal the population structure of T. tor from three locations of Madhya Pradesh, India whereas Sharma et al., (2016)  used RAPD markers to determine the genetic diversity of T. tor from wild and cultures conditions. Till date, there is no documentation on genetic variation with multiple mitochondrial markers in T. tor.
Combination of markers are preferable for resolving stock structures, in order to strengthen our knowledge on historical and current demographic events which are associated in shaping the population structure of a species. For the present study, two mitochondrial genes, i.e., cyt b and ATPase6/8 were used to resolve genetic variation and divergence in T. tor from four riverine populations (Madar, Narmada, Penganga and Godavari) which will be helpful in developing management strategies in order to conserve for sustainable fisheries of this depleting species.
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Tor mahseer Tor tor Hamilton 1822 is an economically important. (2019, Dec 20). Retrieved from https://studymoose.com/tor-mahseer-tor-tor-hamilton-1822-is-an-economically-important-best-essay