An overview of fish fauna of Raigad District, northern Western Ghats, India
Unmesh Katwate 1, Rupesh Raut 2 & Sahir Advani 3
1 Bombay Natural History Society Hornbill House, Opp. Lion Gate, Shaheed Bhagat Singh Road, Mumbai, Maharashtra 400001, India
2 Department of Zoology, Elphinstone College, Mumbai, Maharashtra 400032, India
3 Department of Zoology, The Institute Of Science, Mumbai, Maharashtra 400032, India
Email: 1 firstname.lastname@example.org, 2 email@example.com (corresponding author), 3 firstname.lastname@example.org
The Western Ghats of India harbor rich biodiversity and are aptly classified as one of the 34 Biodiversity Hotspots of the world owing to the concentration of endemism (Mittermeier et al. 2005). The biodiversity of the Western Ghats is under severe threat of deforestation (Myers 1990). Holding only 12,450km2 (i.e. 6.8%) primary vegetation out of an original extent of 182,500km2 primary vegetation, Western Ghats awaits major conservation priorities (Myers et al. 2000). The most important impact is the massive degradation of habitat and extinction of species taking place in a catastrophically short time scale (Novacek 2001), resulting in the modification of both the identities and numbers of species in ecosystems (Tilman 1997).
The literature till date records 288 freshwater fish species from the Western Ghats with 41% fish species endemic to this region (Dahanukar et al. 2004). The fish fauna of northern Western Ghats have been well studied but most of the studies are limited to the east flowing rivers of the Western Ghats while the west flowing rivers have had limited attention (Dahanukar et al. 2011). These west flowing rivers of the northern Western Ghats flow in the Konkan region of Maharashtra, a narrow coastal plain between the Western Ghats and the Arabian Sea. Raigad District forms the middle part of Konkan in the northern Western Ghats. While very few studies are available on fishes of the Konkan region (Annandale 1919; Kulkarni 1947; Bal & Mohmed, 1957; Singh & Yazdani 1988), the Raigad District is even less explored with only three studies (Singh & Yazdani 1993; Arunachalam 2000, 2002) to our knowledge. In our present study we have carried out a more extensive survey to document the diversity of fish fauna of Raigad District and associated threats to the fish fauna.
Raigad District (Image 1) (17051Õ–19o80ÕN & 72051Õ–73040ÕE) forms a major part of northern Konkan and has the Western Ghats on its eastern and southern border (Singh & Yazdani 1993); the eastern and southern part of the district lies in the high rain shadow of the Sahyadri mountains; the altitude ranges from 500 to 1000 m. The annual rainfall ranges from 3000 to 5500 mm in high altitude regions like Matheran. Rainfall decreases in the range of 2000 to 2500 mm as we go from south to north (Chaudhari 1993). Six major west flowing rivers, namely Patalganga, Bhogawati, Amba, Kundalika, Mandad and Savitri with their tributaries, originate from the eastern boundaries of Raigad District and drain into the Arabian Sea (Image 1). These six major rivers with undulating terrains have tropical semi deciduous, semievergreen and some evergreen forest patches in their catchments. In the last few decades, urbanization, industrialization and increasing organic waste load in Raigad District threaten the icthyofauna of these rivers.
During the present survey six sampling sites (Image 1) namely Kharpada (18050Õ42ÓN & 73007Õ20ÓE), Pen (18044Õ03ÓN & 73006Õ49ÓE), Wadkhal (18035Õ41ÓN & 73006Õ10ÓE), Roha (18026Õ03ÓN & 73010Õ36ÓE), Mandad (18020Õ37ÓN & 73007Õ52ÓE) and Mahad (18005Õ20ÓN & 73026Õ46ÓE) situated on the course of Patalganga, Bhogawati, Amba, Kundalika, Mandad and Savitri rivers respectively were selected for experimental fishing. Samples were also collected from local markets and landing centers. For the present study samplings were carried out at all six sampling sites on a monthly basis from August 2008 to July 2011. Experimental fishing was carried out both by members of the survey team as well as by using the expertise of local fisher folk. Different types of gear including cast nets, gill nets, scoop nets (all with varying mesh sizes), traps and other local contrivances were used for collecting the fishes allowing us to sample a range of fish sizes and minimize the bias due to specific gear. At each sampling site different microhabitats like water pools, riffles, cascade, falls, run and plunge were assessed for sampling.
Representative specimens of all fish species were fixed in 4% formaldehyde and transferred to the laboratory and stored in glass bottles. We also visited local fish markets and landing centers situated nearer to the sampling sites to monitor and look for the presence of any species which were not available during our experimental fishing. Samples were subsequently identified by following standard literature (Jayaram 1991; 1999; 2010; Talwar & Jhingran 1991). The threat status of the fish species is adapted from IUCN. Red List of Threatened Species-Version 2011.1 (IUCN 2011). Relative abundance was recorded for each species in each river as rare, common and very common. If a species contributed < 5% or 5% of the total catch in a sample it was considered as rare, if < 50% or 50% it was considered as common and if the species contributed > 50% it was considered as very common.
A total number of 66 fish species belonging to 31 families and 53 genera (Table 1) were collected from the six sampling sites located along the course of monitored rivers. Some of the fishes collected from various rivers are shown in Image 2. Cyprinids were the most dominant group represented by 22 species belonging to 13 genera, followed by the loaches, croakers and gobies of the family Balitoridae, Sciaenidae and Gobiidae respectively (3 species from each family). Kundalika River showed the maximum species number (66 species) followed by Savitri River (64 species) and Amba (61 species). Patalganga River showed the least number of species (45 species) (Fig. 1).
Singh & Yazdani (1993) have reported 106 freshwater and marine fish species in the entire Konkan region of northern Western Ghats of which 41 fish species were recorded from Raigad District. Arunachalam (2000) and Arunachalam et al. (2002) studied Kundalika, Savitri River and Kal River a major tributary of Savitri River as well as Phansad Wildlife Sanctuary area. Arunachalam (2000) recorded 20 fish species, while Arunachalam et al. (2002) reported a total of 22 fish species. Even though we could not record five species recorded by the earlier workers we recorded 18 species for the first time from this area. A cumulative number of species based on previous studies and the current study suggest that there could be at least 71 species of freshwater and secondary freshwater fishes in this region.
In our present study we recorded two bagrids Mystus bleekeri and M. malabaricus. There are earlier records of occurrence of M. seenghala (now Sperata seenghala), M. vittatus and M. keletius in Raigad District (Singh & Yazdani 1993) but during the present study these species were not recorded. Arunachalam (2002) has reported the occurrence of juveniles of Tor khudree from Khandala Falls, an origin of Patalganga River. During the field study, issues of occurrence of Tor khudree with local fishermen were discussed. As per their knowledge this species is very rarely seen in the wild in this area but is known to be cultivated in farms in some areas of Raigad District. We could not record the presence of Tor khudree in our study. Nevertheless, even in the absence of species like M. seenghala, M. vittatus, M. keletius, Gonoproktopterus curmuca and Tor khudree recorded earlier (Singh & Yazdani 1993; Arunachalam 2002), we have reported 18 new records of fish species to Raigad District, namely Anguilla bengalensis, Cirrhinus cirrhosus, Crossocheilus latius, Esomus danrica, Garra gotyla stenorhynchus, Labeo calbasu, Puntius chola, Parapsilorhynchus discophorus, Ompok bimaculatus, Heteropneustes fossilis, Xenentodon cancila, Monopterus indicus, Etroplus maculatus, Eleotris fusca, Channa punctata, C. gachua, Chanda nama and Mastacembalus armatus. Our study also reported eight new records of introduced fish species to this region like Catla catla, Cirrhinus mrigala, Ctenopharyngodon idella, Cyprinus carpio, Labeo rohita, Clarias gariepinus, Gambusia affinis and Poecilia reticulata. Puntius cf. amphibius collection reported in the present study has ambiguous taxonomic status. Pethiyagoda & Kottelat (2005, p.151) considered Puntius amphibius from its lectotype which was preserved some two centuries ago from Bombay Presidency, a rather ill defined type locality as it points to a very large region. Our Puntius cf. amphibius specimens do not match with the lectotype of Puntius amphibius sensu stricto because of the presence of a dark oval blotch on caudal peduncle, which is absent in lectotype studied by Pethiyagoda & Kottelat (2005, p.150). Pethiyagoda & Kottelat (2005, p.150) distinguished Puntius amphibius from Puntius mahecola by having a smaller eye diameter (61.6% of snout length, vs. 68.4–100.0 %). Eye diameter of our Puntius cf. amphibius collection ranges between 71–98 % of snout length, which falls closer to P. mahecola, a species restricted to southern Western Ghats (Pethiyagoda & Kottelat 2005). Such variations between our Puntius cf. amphibius collection and lectotype of Puntius amphibius studied by Pethiyagoda & Kottelat (2005) suggest that there is a need to reinvestigate Puntius amphibius from its type locality with a fresh collection.
Out of the recorded 66 fish species, five species are categorized as vulnerable globally. These species are Cirhinus cirrhosus, Cyprinus carpio, Devario fraseri, Parapsilorhynchus discophorus and Monopterus indicus (IUCN 2011). Western Ghats endemics like Devario fraseri, Garra gotyla stenorhynchus, Puntius sarana subnasutus, Parapsilorhynchus discophorus, Nemachilichthys rueppelli, Mystus malabaricus and Monopterus indicus constitute 10% to the total fish species of the study area. The global threat status of the studied fish species shows that 7.5% belong to Vulnerable (VU), 6% to Near Threatened (NT), 56% to Least Concern (LC) while 3% has Data Deficient (DD). The status of around 26% species was not available (Fig. 2). Kundalika, Savitri and Amba show maximum contribution (6–7.5 %) of globally vulnerable species in their species assemblages (Table 2).
Raigad District is showing rapid industrialization. The fish fauna of Raigad District is threatened mainly due to pollution, industrial sewage disposal in river systems, habitat alteration due to construction of dams, indiscriminate deforestation on a large scale, and over-exploitation of present fish stock and introduction of exotic fish species. Nine introduced fish species like Catla catla, Cirrhinus mrigala, Ctenopharyngodon idella, Cyprinus carpio, Labeo rohita, Clarias gariepinus, Gambusia affinis, Poecilia reticulata and Oreochromis mossambicus were collected from the different sampling sites which constituted about 13% of the total fish fauna. Fishes like Catla catla, Cirrhinus mrigala and Labeo rohita were native to the Ganges River systems and introduced in greater numbers for mass aquaculture practices. Studies suggest that native fish fauna of the Western Ghats are severely threatened by the introduction of alien fish species with regard to predation, competition for food and other resources, and also with the introduction of new pathogens (Daniels 2006; Raghavan et al. 2008; Krishnakumar et al. 2009; Knight 2010). These exotic populations have the status of potential pests and hence pose a serious threat to the fish fauna of Raigad District, especially to the endemic and threatened species having a low population size.
It is recommended that further long term intensive monitoring studies are needed to trace the impact of anthropogenic activities on the freshwater fish fauna of Raigad District. Implementation of conservation measures are also necessary to protect the locally, as well as globally threatened freshwater fish species from this area.
Annandale, N. (1919). Bombay streams fauna: notes on fresh water fish mostly from the Satara and Poona Districts. Records of the Indian Museum 16: 125–138.
Arunachalam, M. (2000). Assemblage structure of stream fishes in the Western Ghats (India). Hydrobiologia 430(1–3): 1–31.
Arunachalam, M., A. Sankaranarayanan, A. Manimekalan, R. Soranam & J.A. Johnson (2002). Fish fauna of some streams and rivers in the Western Ghats of Maharashtra. Journal of Bombay Natural History Society 99(2): 337-341.
Bal, D.V. & Mohmed (1957). A systematic account of the eels of Bombay. Journal of the Bombay Natural History Society 54(3): 732–740.
Chaudhari, K.K. (1993). Gazetteer of the Raigad District. Maharashtra State Gazetteers Department, Govt. of Maharashtra, 30–42pp.
Dahanukar, N., R. Raut & A. Bhat (2004). Distribution, endemism and threat status of freshwater fishes in the Western Ghats of India. Journal of Biogeography 3(1): 123–136.
Dahanukar, N., R. Raghavan, A. Ali, R. Abraham & C.P. Shaji (2011). The status and distribution of freshwater fishes of the Western Ghats, pp. 21–48. In: Molur, S., K.G. Smith, B.A. Daniel & W.R.T. Darwall (compilers). The Status of Freshwater Biodiversity in The Western Ghats, India. International Union for Conservation of Nature (IUCN) Gland, Switzerland & Zoo Outreach Organization (ZOO) Coimbatore, India, 116pp.
Daniels, R.J.R. (2006). Introduced fishes: a potential threat to the native freshwater fishes of peninsular India. Journal of the Bombay Natural History Society 103(2–3): 346–348.
IUCN (2011). IUCN Red List of Threatened Species. Version 2011.1. <www.iucnredlist.org>. Downloaded on 09 August 2011.
Jayaram, K.C. (1991). Revision of the Genus Puntius Hamilton from the Indian Region (Pisces: Cypriniformes, Cyprinidae, Cyprininae). Occasional Paper No. 135. Records of the Zoological Survey of India, Kolkata, 178pp.
Jayaram, K.C. (1999). The Freshwater Fishes of the Indian Region. Narendra Publishing House, New Delhi, 551pp.
Jayaram, K.C. (2010). The Freshwater Fishes of The Indian Region. Second Edition. Narendra Publishing House, Delhi, 616pp.
Knight, J.D.M. (2010). Invasive ornamental fish: a potential threat to aquatic biodiversity in peninsular India. Journal of Threatened Taxa 2(2): 700–704.
Krishnakumar, K., R. Raghavan, G. Prasad, A. Bijukumar, M. Sekharan, B. Pereira & A. Ali (2009). When pets become pests - exotic aquarium fishes and biological invasions in Kerala, India. Current Science 97(4): 474–476.
Kulkarni, C.V. (1947). Notes on freshwater fishes of Bombay and Salsette Islands. Journal of the Bombay Natural History Society 47(2): 319–326.
Mittermeier, R.A., P.R. Gil, M. Hoffman, J. Pilgrim, T. Brooks, C.G. Mittermeier, J. Lamoreux, & G.A.B. da Fonseca (2005). Hotspots Revisited: EarthÕs Biologically Richest and Most Endangered Terrestrial Ecoregions. Cemex, Mexico, 392pp.
Myers, N. (1990). The biodiversity challenge: expanded hotspots analysis. The Environmentalist 10: 243–256.
Myers, N., R.A. Mittermeier, C.G. Mittermeier, G.A.B. Da Fonseka & J. Kents (2000). Biodiversity hotspots for conservation priorities. Nature 403: 853-858.
Pethiyagoda, R. & M. Kottelat (2005). The identity of the South Indian Barb Puntius mahecola (Teleostei: Cyprinidae). The Raffles Bulletin of Zoology (Supplement No.) 12: 145–152.
Raghavan, R., G. Prasad, P.H. Anvar-Ali & B. Pereira (2008). Exotic fish species in a global biodiversity hotspot: observations from river Chalakudy, part of Western Ghats, Kerala, India. Biological Invasions 10(1): 37–40.
Singh, D.F. & G.M. Yazdani (1988). A note on the ichthyofauna of Sanjay Gandhi National Park, Borivli, Bombay. Journal of the Bombay Natural History Society 85: 631–633.
Singh, D.F. & G.M. Yazdani (1993) Ichthyofauna of Konkan Region of Maharashtra (India). Occasional paper no. 145, Records of the Zoological Survey of India, Kolkata, 46pp.
Talwar, P.K. & A.G. Jhingran (1991). Inland Fishes of India and Adjacent Countries. Oxford-IBH Publishing Co. Pvt. Ltd., New Delhi, 1158pp.
Tilman, D., J. Knops, D. Wedin, P. Reich, M. Ritchie & E. Siemann (1997). The influences of functional diversity and composition on ecosystem processes. Science 277: 1300–1302.