Coldwater Fish Diversity of India and Its Sustainable Development A. K. Singh* and M. S. Akhtar ICAR-Directorate of Coldwater Fisheries Research, Bhimtal-263136, Nainital, Uttarakhand *Email: [email protected] Introduction India is one of the mega biodiversity hotspots in the world and occupies the 9th position in terms of freshwater mega biodiversity (Mittermeier et al., 1997). Biodiversity is essential for stabilization of ecosystems, protection of overall environmental quality, for understanding intrinsic worth of all species on the earth (Ehrlich and Wilson, 1991). The country is bestowed with vast and varied coldwater/hill fishery resources which are spread over the Himalayan and peninsular regions as upland rivers, streams, high and low altitude natural lakes and reservoirs. There are around Fig. 1 : Number of species present in the North-East India 8,243 km long streams and rivers, 20,500 ha (Ali, 2010) natural lakes, 50,000 ha of reservoirs, both natural and manmade, and 2500 ha brackish water lakes in central Himalaya and 91 from the Deccan plateau the high altitude (Mahanta & Sarma, 2010). The (Fig. 1). Coldwater rivers and hill streams are known for The commercially important Indian coldwater their high velocity water fall, rapid cascades, deep species are Tor tor, T. putiora, T. mosal, T. pools and substratum comprising bed rock - progeneius, T. khudree, T. mussullah, T. mala- boulder - sand. These vast and varied water baricus, Naziritor chelynoides, Neolissochielus resources in the uplands harbour rich ichthy- wynaadensis, N. hexagonolepis, Schizotho- ofaunal diversity comprising large populations of raichthys progastus, S. esocinus, Schizothorax indigenous and exotic, cultivable and non- richardsonii, S. plagiostomus, S. curvifrons, S. cultivable fish species (Sehgal, 1999; Mahanta and micropogon, S. kumaonensis, Barilius bendelisis, Sarma, 2010). The low productivity and higher B. vagra, B. shacra, B. (Raiamas) bola, Bangana dero, degree of resource seasonality and unpredict- Labeo dyocheilus, Crossocheilus periyarensis, ability give rise to a unique diversity of aquatic life Semiplotus semiplotus, Osteobrama belangeri, which is usually prone to many types of Garra lamta, Garra gotyla gotyla, Glyptothorax disturbances (Bhatt et al., 2012; Jena and pectinopterus, G. brevipinnis, G. stoliczkae, Gopalakrishnan, 2012; Singh et al. 2014). Chagunius chagunio, Labeo dero, L. dyochilus and Lepidopygopsis typus (Fig. 2) (Sehgal, 1999; Sunder Coldwater Fish Diversity et al., 1999; Jena and Gopalakrishnan, 2012; The coldwater fisheries harbour 258 species Sehgal, 2012). belonging to 21 families and 76 genera. Out of Mahseer is a group of game fish that belongs these, the maximum of 255 species are recorded primarily to the genus Tor, but also includes some 97 from North-East Himalaya, 203 from the west and species of the genus Neolissochilus (e.g. Chocolate Neolissochilus hexagonolepis Osteobrama belangeri Semiplotus semiplotus Tor putitora Tor tor Tor progenius Cirrhinus reba Garra elongata Garra gotyla Labeo dyocheilus Barilius bendilisis Danio dangila Raiamas bola Schizothorax richardsonii 98 Fig. 2: Important coldwater fish species (Photos reproduced from Mahanta et al., 2011) mahseer Neolissochilus hexagonolepis). Schizo- (i) Habitat destruction/modification: The thoracines (family cyprinidae and sub-family occurrence of destructive natural events such schizothoracinae) on the other hand, contribute to a s f l o o d s a n d l a n d s l i d e s , c h a n g e i n an economically significant group of hill stream environmental flow, biological invasion and fishes all along the Himalayan belt especially from many others, greatly affected the coldwater Kashmir Himalaya. Out of about 258 cold water fish ecosystem in Himalayan region causing severe species (both indigenous and exotic) reported from threat to coldwater fish diversity. Pollution, Indian uplands, 17 members of snow-trout’s (locally increased sedimentation, flow alteration and known as Asela, Sela or Rasella in Uttarakhand, water diversion, and introduced species are Gulgali in Himanchal and Koushargad in Kashmir identified as the main causes for decreased Himalayas) have been recognized by many authors ichthyofaunal diversity in Asian countries (Talwar and Jhingran, 1991; Tilak, 1987 and Sundar (Nguyen and De Silva, 2006; Singh and Lakra, et al., 1999). Of these, 10 species belong to genus 2011; Singh et al., 2013; Singh et al. 2014). Schizothorachthys species being (niger, esocinus, During the past few years, the coldwater rivers curvifrons, longipinnias, micropogon, planifrons, and lakes harbouring original wild stock of hugelli, labiatus, nasus, progastus), two to genus precious fish species viz. mahseer, snow trout, Schizothorax (species being richardsonii and minor carps, etc. have greatly shrunk in view kumaonensis) and one each to Diptychus (macu- of recurrent floods and consequent ecological lates), Gymnocypris (biswasi), Lepidopygopsis degradation. (typus), Ptychobarbus (conirostris), Schizopygopsis (stoliczkae). Only Lapidopygopisis typus is (ii) Overfishing/over exploitation: Over- restricted to Periyar lake (Western ghats), Kerala. All exploitation of species affects the loss of other species are available from Jammu and genetic diversity and the loss in the relative Kashmir region. Schizothorax richardsonii is most species abundance of both individual and /or common and widely distributed species in groups of interacting species. The population Himalayan belt (Sehgal, 1999). size gets reduced because of disturbances in age structure and sex composition (Sarkar et al., Major Threats to Coldwater Fish 2008; Singh, 2012). Over-fishing also affects Diversity heritable life history parameters like growth and age of sexual maturity. Efficient gears The aquatic environments are experiencing remove quick growing larger individuals. serious threats to both biodiversity and ecosystem Consequently, the proportion of slow growing stability requiring several strategies and priorities ones increases and the average size of to address this crisis (Jena and Gopalakrishnan, individuals in a population decreases. 2012; Singh et al. 2014). Despite the central role of fish biodiversity in an ecosystem, all fish species The National Commission on Agriculture that together comprise fish biodiversity face (NCA, 1976; Nautiyal, 2013) in its report on different risks and threats. The threats could be fisheries stated that there was general decline manmade or environmental, or in combination in the mahseer fishery due to indiscriminate with interlinked effects. Such threats are wide fishing of brooders and juvenile fishes and ranging causing habitat alterations, shrinkage of adverse effects of river valley projects. The resources, reduction of natural habitat area, stress on the mahseer population is not only germplasm loss etc on account of reducing water due to their overexploitation for its table value discharge in rivers, siltation, overfishing, pollution but also due to the rise in developmental of water bodies, introduction/entry of non-native activities, especially the growing number of fish species and climatic vagaries etc. The major hydroelectric-cum-irrigation projects which 99 threats to the coldwater fish diversity are: have fragmented and deteriorated its natural h a b i t a t ( N a u t i y a l a n d S i n g h , 1 9 8 9 ) . the natural water bodies of India (Singh, 2014). Consequently, mahseer population has The introduction of Cyprinus carpio var. critically declined from some areas (Kashmir, specularis into Dal lake and Loktak lake has Nainital) and declined rapidly over the last few been reported to affect the population of decades owing to which it was accorded a indigenous Schizothorax sp. and Osteobrama ‘threatened’ status in India (Khan and Sinha, belangeri, respectively (Singh and Lakra, 2011). 2000; Mahanta and Sarma, 2010; Akhtar et al., The population of native Catla and mahseer 2014). Despite this, the use of rugged methods were depleted considerably in Govind Sagar like dynamite, bleaching powder, pesticides reservoir after the introduction of silver carp and damming along with indiscriminate fishing (Singh and Lakra, 2011). Introduction of silver leading to mass mortality of brood fishes and carp in Indian reservoirs has had in general, a juveniles has continued unabatedly especially negative impact on fish diversity (Singh and in small streams, which are the breeding Lakra, 2011). grounds of mahseer (Nautiyal 1994a), thus (iv) Climate change: Climate variability is a key effecting the recruitment rates adversely. factor controlling the distribution and (iii) Introduction of exotic species: The abundance of aquatic organisms and ecosystem introduction of exotic aquatic organisms, structure (Jena and Gopalakrishnan, 2012). particularly fishes, brought about a worldwide The climate change impact on fish depends on concern as it resulted in a wide array of the magnitude of change, and on the sensitivity problems including extirpation of indigenous of particular species or ecosystem. The impact species (Singh and Lakra, 2011; Singh et al., of temperature shift due to climate change on 2013). The exotics are a competition to aquatic organisms will affect their biological indigenous fishes for food and habitat (Singh et functions, as most of them are poikilothermic al., 2013). They may prey upon native fishes, in nature. In temperate regions, coldwater introduce new diseases and parasites, result in fishes are important ecological indicators