Freshwater fish fauna of Krishna River at Wai, northern Western Ghats,
India
Sanjay S. Kharat 1, Mandar Paingankar 2 &
Neelesh Dahanukar 3
1 Department of
Zoology, Modern College of Arts, Science and Commerce, Ganeshkhind, Pune,
Maharashtra 411007, India
2,3 Zoo Outreach
Organization, 96 Kumutham Nagar, Villankurichi Road, Coimbatore, Tamil Nadu
641035, India
3 Indian
Institute of Science Education and Research, Sai
Trinity, Garware Circle, Pune, Maharashtra 411021, India
Email: 1 kharat.sanjay@gmail.com,2 mandarpaingankar@gmail.com, 3 n.dahanukar@iiserpune.ac.in(corresponding author)
Date of publication (online): 26 June 2012
Date of publication (print): 26 June 2012
ISSN 0974-7907 (online) | 0974-7893 (print)
Editor: W. Vishwanath
Manuscript details:
Ms
# o2796
Received
05 May 2011
Final
revised received 08 April 2012
Finally
accepted 21 May 2012
Citation: Kharat S.S.,
M. Paingankar & N. Dahanukar (2012). Freshwater fish fauna of Krishna River
at Wai, northern Western Ghats, India Journal of Threatened Taxa 4(6):
2644–2652.
Copyright: © Sanjay S.
Kharat, Mandar Paingankar & Neelesh Dahanukar 2012. Creative
Commons Attribution 3.0 Unported License. JoTT allows unrestricted use
of this article in any medium for non-profit purposes, reproduction and
distribution by providing adequate credit to the authors and the source of
publication.
Acknowledgements: We are
thankful to Dr. R.M. Sharma, Officer-in-charge, and Shrikant Jadhav, Zoological
Survey of India, Western Regional Center, Akurdi, Pune, for encouragement and
helpful discussion. The study was self funded. The
CEPF-funded freshwater assessment of the Western Ghats encouraged us to publish
this work. We duly acknowledge the help from CEPF for publication of this
article.
Abstract: Freshwater
fish fauna of the Krishna River at Wai, and the Dhom reservoir upstream of Wai,
was studied. Fifty
one species belonging to 14 families and 33 genera were recorded; 13
endemic to the Western Ghats and two to the Krishna River system. Moderate to rare populations were found
for six globally threatened species: Gonoproktopterus
curmuca, Labeo
potail, Schismatorhynchos
nukta, Tor
khudree, T.
mussullah and Parapsilorhynchus
discophorus. Fish
in this area are under threat due to two introduced species and five
transplanted species, and due to other anthropogenic activities such as
overfishing and organic and inorganic pollution of the river. Site based conservation action plans
are needed for conservation of rare and threatened fish in this area.
Keywords: Freshwater
fish fauna, Krishna River system, Threats.
This article
forms part of a special series on the Western Ghats of India, disseminating the
results of work supported by the Critical Ecosystem Partnership Fund (CEPF), a
joint initiative of l’Agence Française de Développement, Conservation
International, the Global Environment Facility, the Government of Japan, the
MacArthur Foundation and the World Bank. A fundamental goal of CEPF is to
ensure civil society is engaged in biodiversity conservation. Implementation of
the CEPF investment program in the Western Ghats is led and coordinated by the
Ashoka Trust for Research in Ecology and the Environment (ATREE).
For figures, images, tables -- click here
Krishna
River originates in Wai Taluka, Satara District, Maharashtra,
India. The river flows west-east and the first major dam along its course is Dhom
Dam, while the first major city is Wai. Some studies are available on the fish fauna of Krishna River at Wai and
Dhom reservoir. Silas (1953)
recorded nine species of freshwater fish from the river at Wai. Jayaram (1995) studied the entire
Krishna River system and mentioned that collections were made from both Dhom
reservoir and Krishna River at Wai. However, he did not provide a separate checklist of fish in this area. As an offshoot of the same work,
Srithar & Jayaram (1990) described a species, Salmophasia longicauda, and suggested that both S. longicauda and an
allied species S. novaculaare found in the fish catches of Dhom reservoir. Arunachalam et al. (2002) recorded 14 species of freshwater
fish from Dhom reservoir. Taken
together, these studies list 22 fish species in this area, which is an under
representation compared to checklists from other tributaries of the Krishna
River system (Kharat et al. 2003; Jadhav et al. 2011; Dahanukar et al.
2012). There is no documentation
of threats to fish species in this area. In the present work we have studied the fish fauna of both Dhom
reservoir and Krishna River at Wai in order to document both diversity and
threats.
Fish
were collected from Krishna River at Dhom reservoir (17.9810N
& 73.8000E) and from an
approximately 15km stretch between Dhom Dam and downstream of Wai (17.9300N
& 73.9220E) (Image 1). Study was carried out for two years
from May 2009 to April 2011. Fish
were collected from local fishermen and local markets at Wai (17.9520N
& 73.8870E). Only one or two
specimens of each species were preserved while remaining specimens were
identified in the field. Large
sized common fish species and introduced fish species were not collected. Collected specimens were preserved in
4% formaldehyde and their identification was confirmed using available
literature (Jayaram 1991; 2010; Jayaram & Dhas 2000; Jayaram & Sanyal
2003; Menon 1987; Talwar & Jhingran 1991). Collected fish specimens are deposited in the Zoological
Survey of India, Western Regional Centre, Akurdi, Pune, under the accession
numbers from P/2628 to P/2665. Assuming that the fishing effort for a given type of net (gill net or
drag net) was constant, relative abundance of the fish (for each type of net
separately) was grossly categorized into four discrete categories, viz:
abundant (76–100 % of the total catch), common (51–75 % of the
total catch), moderate (26–50 % of the total catch) and rare (1–25
% of the total catch). Category for
different species was determined for each catch separately and the most
consistent category for a given species was chosen.
A
total of 51 fish species belonging to 14 families and 35 genera were recorded
(Table 1). Of these, 15 fish
species are endemic to the Western Ghats of India while five are endemic to the
Krishna River system. Out of a
total 51 species, 49 fish species were recorded from Krishna River at Wai while
42 fish species were recorded from Dhom reservoir. Abundance-wise distribution suggests that Krishna River at
Wai hosts 11 abundant, six common, 20 moderate and 12 rare fish species. Similarly, in Dhom reservoir, there are
five abundant, 14 common, 16 moderate and seven rare fish species.
Of
the nine species of freshwater fish recorded by Silas (1953) from Krishna River
at Wai (Table 2), we could record all species. However, of the 14 species recorded by Arunachalam et al.
(2002) from Dhom reservoir (Table 2), we could not record four species, namely Puntius conchonius, Indoreonectes evezardi,
Nemachilichthys ruppelli and Eugnathogobius oligactis. Even though Srithar & Jayaram (1990) recorded both Salmophasia longicauda and S. novacula from the
Dhom reservoir, we could not distinguish two separate species in the fish
catches. Therefore, following the
synonymization of S.
longicauda with S.
novalula by Menon (1999) and Eschmeyer (2012), we have
recorded only S. novaculafrom the study area. Thus, currently the total number of freshwater fish
species known from Krishna River at Wai area is 55.
Six
species found in Krishna River at Wai and Dhom reservoir, viz., Gonoproktopterus curmuca,Labeo potail,Parapsilorhynchus discophorus,Schismatorhynchos nukta,Tor khudreeand T. mussullah, (Image
2) are considered as globally threatened species, while two other species, Mystus malabaricusand Ompok bimaculatus,
are considered as Near Threatened (IUCN 2011). Current study area holds an
abundant to moderate to rare populations of these species.
Labeo potailwas assessed as Endangerd (EN) based on a conservative estimate of global
population decline of this species by 50–60 % in the last 10 years caused
by decline in the habitat quality owing to organic and inorganic pollution of
rivers, harvesting of fish for consumption and competition created by
transplanted carps (Dahanukar 2011a). Labeo
potail is found rarely in both the Dhom reservoir and the
downstream Krishna River in the study area and the species is facing similar
stressors mentioned before. Raghavan (2011) assessed Tor
khudree as EN owing to its high exploitation as a food fish,
which might have resulted in drastic declines in the population of this species
by more than 60% in the last 10 years. Raghavan et al. (2011) showed that the harvesting of this species from
the wild populations is unsustainable and suggested that if conservation
actions directed towards the species are not implemented the species might face
a drastic reduction in the recent future. This species is found in moderate numbers in the Krishna River at Wai
and is common in the Dhom reservoir. Nevertheless, the species is highly preferred as a food fish and fetches
a good value in the fish market. Therefore, it is likely that the species could
be under fishing pressure. Another
allied species Tor mussullahis assessed as EN since it exists in the Western Ghats as severely fragmented
populations and the population of this species is declining severely in most
parts of its current distribution due to habitat modifications caused by
pollution, heavy harvest of the species and competition created by the
introduced alien species (Dahanukar & Raghavan 2011). Tor mussullah is a very rare species in the
current study area.
Discussions
with fishermen in this area indicate that populations of Schismatorhynchos nuktahave declined drastically in the recent past. Similar concerns were raised by Ghate et
al. (2002) for this species from other tributaries of the Krishna River
system. Ghate et al. (2002),
Kharat et al. (2003) and Dahanukar et al. (2012) suspected pollution of the rivers
and heavy harvest of the fish resources as possible causes for decline of this
species from other rivers. On
similar lines, we think that heavy harvesting of all large carps including S. nukta is a
possible threat to fish fauna of Krishna River at Wai. Jayaram (1995) suggested that S. nukta is not much
preferred as food. This is also
true in the current study area because this species had relatively low demand
as compared to other carps. Therefore, we think that the heavy harvest of this species could be
attributed to unintentional catches along with other major carps. Competition created by other introduced
carps like Catla catla,Cirrhinus mrigalaand Labeo rohitacould also be a possible threat to the species as it shares the same niche. Based on the same stressors and the
fact that the population of this species is declining drastically, this species
is assessed as EN (Dahanukar 2011c).
An
endemic species of northern Western Ghats Parapsilorhynchus discophorus is assessed as
Vulnerable (VU) owing to the fact that breeding habitats of the species on the mountain tops are threatened by habitat modification due to
recreational activities (Dahanukar 2011b). The species is found in moderate numbers in the small
streams draining in the Krishna River at Wai. Increasing urbanization, tourism and recreational activities
in the mountain tops near this area, especially at
Pachgani and Mahabaleshwar, are likely to affect the breeding habitats of the
species.
Commenting
on the threat status of Gonoproktopterus curmuca is not as easy as other
species in this area. Abraham
(2011) assessed Hypselobarbus
curmuca as EN owing to the fact that the species is threatened
throughout its range by habitat destruction and targeted fishing, which might
have lead to population decline by more than 50% in the last 10 years whereas,
Raghavan & Ali (2011) assessed Hypselobarbus
kolus as VU based on population decline of 30–40 % in
the wild populations within last ten years due to overexploitation, destructive
fishing practices and decline in the quality of habitat. In the book by Jayaram (2010),
considered H. kolus a junior subjective synonym
of H. curmucaand the genus is considered valid as Gonoproktopterus. If both H. kolus and H. curmuca are indeed
one and the same species then the species G. curmuca might have a different threat status
or it might be assessed as Least Concern (LC) based on the wide
distribution. This uncertainty in
taxonomic status and its effects on assigning the threat status bolsters the
arguments raised by Molur et al. (2011) and Raghavan et al. (2012) that
resolving the taxonomic issues is essential for assigning conservation status
of a species. Nevertheless, G.
curmuca is abundant in the study area although it is also
subjected to heavy harvest. In the
absence of detailed studies regarding the fishing trends it is difficult to
state whether the harvesting of this species in the study area is sustainable
or not.
The
fish fauna of Krishna River at Wai is threatened due to several factors including
heavy harvesting of fish resources, competition and predation by introduced
species and habitat degradation due to organic and inorganic pollution (Image
3). In the Upstream, the river is
also threatened by tourism and associated recreational activities. Most of the river stretch is affected
by organic and inorganic pollution seeping from adjacent agricultural
lands. Especially in Wai the river
is polluted due to organic and inorganic pollutants contributed by household
waste, recreational activities and tourism. Even though the effect of these pollutants on the fish fauna
of this area is not exactly known, decline in many endemic and threatened
species could be partially attributed to them.
In
the light of global decline in biodiversity, especially in areas like the
Western Ghats, which harbors rich diversity of endemic freshwater fish,
systematic conservation plans to monitor and conserve freshwater fish of Wai
area are essential. Because Wai
also hosts a number of globally threatened species, there is a need for site
based management plans in this area. We suggest following management plans: (i) check on the fishing
activities in the backwaters of Dhom Dam especially during the breeding season
(May to August), (ii) monitoring of the water quality and check on the release
of untreated organic and inorganic wastes in the river, (iii) promotion of
environment friendly agricultural practices along the river banks, and, (iv)
strict regulations regarding tourism related anthropogenic stressors.
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