The legendary hump-backed mahseer Tor sp. of India's River Cauvery: An endemic fish swimming towards extinction?

Abstract

The Western Ghats region of India is an area of exceptional freshwater biodiversity and endemism. Mahseer of the genus Tor are considered prized sport fishes of great cultural significance; nevertheless, they are threatened as a result of increasing anthropogenic stressors. In the River Cauvery, the mahseer community comprises a 'blue-finned' and an orange-finned, 'hump-backed' fish. Whilst it is not yet known whether these are distinct species or 2 different phenotypes, evidence suggests that the hump-backed phenotype is endemic to the river, whereas the blue-finned phenotype was introduced in the 1980s. Angler-catch data from a managed fishery on the River Cauvery, gathered between 1998 and 2012 and comprising 23 620 h of fishing effort, revealed that captured individuals ranged in size from 0.45 to 46.8 kg, with the blue-finned phenotype comprising 95% of all captured fish and the remainder being hump-backed. The catch per unit effort (CPUE) of the blue-finned phenotype significantly increased over the study period, while the mean weight of individual fish significantly declined. By contrast, the CPUE of the hump-backed phenotype declined significantly over the period, with individual mean weights significantly increasing. These data suggest a recent recruitment collapse in the hump-backed phenotype resulting in an ageing population that may be headed towards extinction. The introduced blue-finned phenotype, however, continues to recruit strongly, suggesting that the mahseer community of the River Cauvery has undergone considerable shifts in the last 30 yr.

Full text

ENDANGERED SPECIES RESEARCH
Endang Species Res
Vol. 28: 11–17, 2015
doi: 10.3354/esr00673 Published online May 13
INTRODUCTION
Freshwater ecosystems and their biodiversity re -
main among the most endangered and poorly pro-
tected resources on Earth (Millennium Ecosystem
Assessment 2005, Dudgeon 2011, Cooke et al. 2012),
with almost 1 in 3 freshwater species facing a high
risk of extinction (Collen et al. 2014). Of the 5785 spe-
cies of freshwater fish assessed for their conservation
status by the IUCN, more than 36% are threatened,
and over 60 species have gone extinct since 1500
(Carrizo et al. 2013).
The Western Ghats region of India, part of the
Western Ghats-Sri Lanka Biodiversity Hotspot, is
an area of exceptional freshwater biodiversity and
en demism (Dahanukar et al. 2011, Raghavan et al.
2015). Nevertheless, approximately half of the
region’s endemic fish species are threatened with
© The authors 2015. Open Access under Creative Commons by
Attribution Licence. Use, distribution and reproduction are un -
restricted. Authors and original publication must be credited.
Publisher: Inter-Research · www.int-res.com
*Corresponding author: apinder@bournemouth.ac.uk
The legendary hump-backed mahseer Tor sp. of
India’s River Cauvery: an endemic fish swimming
towards extinction?
Adrian C. Pinder1,2,*, Rajeev Raghavan1,3, 4, J. Robert Britton2
1Mahseer Trust, c/o The Freshwater Biological Association, East Stoke River Laboratory, Wareham, Dorset BH20 6BB, UK
2Faculty of Science and Technology, Bournemouth University, Fern Barrow, Poole, Dorset BH12 5BB, UK
3Conservation Research Group (CRG), St Albert’s College, Kochi, Kerala, 682 018, Kerala, India
4Laboratory of Systematics, Ecology and Conservation, Zoo Outreach Organization (ZOO), Coimbatore, 641 035, Tamil Nadu, India
ABSTRACT: The Western Ghats region of India is an area of exceptional freshwater biodiversity
and endemism. Mahseer of the genus Tor are considered prized sport fishes of great cultural sig-
nificance; nevertheless, they are threatened as a result of increasing anthropogenic stressors. In
the River Cauvery, the mahseer community comprises a ‘blue-finned’ and an orange-finned,
‘hump-backed’ fish. Whilst it is not yet known whether these are distinct species or 2 different
phenotypes, evidence suggests that the hump-backed phenotype is endemic to the river, whereas
the blue-finned phenotype was introduced in the 1980s. Angler-catch data from a managed fish-
ery on the River Cauvery, gathered between 1998 and 2012 and comprising 23 620 h of fishing
effort, revealed that captured individuals ranged in size from 0.45 to 46.8 kg, with the blue-finned
phenotype comprising 95% of all captured fish and the remainder being hump-backed. The catch
per unit effort (CPUE) of the blue-finned phenotype significantly increased over the study period,
while the mean weight of individual fish significantly declined. By contrast, the CPUE of the
hump-backed phenotype declined significantly over the period, with individual mean weights
significantly increasing. These data suggest a recent recruitment collapse in the hump-backed
phenotype resulting in an ageing population that may be headed towards extinction. The intro-
duced blue-finned phenotype, however, continues to recruit strongly, suggesting that the mahseer
community of the River Cauvery has undergone considerable shifts in the last 30 yr.
KEY WORDS: Western Ghats · Tor khudree · Tor mussullah · Catch and release · Endemic ·
Recruitment · Recreational fisheries
O
PEN
PEN
A
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Endang Species Res 28: 11–17, 2015
extinction (Dahanukar et al. 2011), a result of esca-
lating anthropogenic pressures and threats, lack of
governmental support for freshwater fish conserva-
tion, jurisdictional issues and oversights, poor en -
forcement of existing laws and implementation of
top-down approaches (Dahanukar et al. 2011, Rag-
havan et al. 2011, 2013, Pinder & Raghavan 2013).
In the region, no freshwater fish has received as
much attention from the public as the mahseer (Tor
spp.), a group of large-bodied fishes of the Cypri -
nidae family. These species are represented in the
ancient Indian literature (Nautiyal 2014), are
revered as gods (Dandekar 2011) and have been
globally recognised as premier game fishes since
colonial times (Thomas 1873, Dhu 1923, MacDonald
1948). They are, however, among the most threat-
ened groups of freshwater fish in the Western
Ghats, impacted by habitat loss and destructive
fishing, yet there are many gaps in our knowledge
of their taxonomy, natural histories and population
statuses (Pinder & Raghavan 2013). Of particular
concern are their systematics and taxonomy, with
continuing ambiguity about the identity and distri-
bution of species. The increasing volume of infor-
mation in the peer-reviewed literature has also
been relatively unhelpful to date as it often pro-
vides contrasting perspectives on these subjects (cf.
Knight et al. 2013, Khare et al. 2014).
In British colonial times, the mahseer of the River
Cauvery in the Western Ghats were premier sport
fishes, but interest in their fishery diminished follow-
ing Indian independence in 1947, leading many to
assume the fish had become extinct. In 1978, how-
ever, a small team of British explorers were success-
ful in catching mahseer weighing up to 42 kg (TWFT
1984), reigniting global interest in the river as a pre-
mier freshwater sport fishing destination and launch-
ing a new era of Indian angling ecotourism (Everard
& Kataria 2011). The fishery was developed on strict
catch-and-release (C&R) principles that realised tan-
gible river conservation and societal benefits (Pinder
& Raghavan 2013). Despite these benefits, govern-
mental reinterpretation of the Indian Wildlife Protec-
tion Act of 1972 resulted in a shutdown of the angling
camps from 2012, exposing aquatic biodiversity gen-
erally and mahseer specifically to elevated levels of
illegal and destructive levels of exploitation (e.g.
dynamite fishing) in the river.
A recent study on the mahseer fishery of the River
Cauvery highlighted the value of angler catch
returns in monitoring temporal population trends in
mahseer numbers and weight (Pinder et al. in press),
and highlighted a marked shift in the weight of indi-
vidual fish being captured despite a relatively consis-
tent methodology used across the time series, with
increasingly smaller fish being captured over time.
Although the study speculated that this related to a
change in the mahseer community structure from the
endemic hump-backed (orange-finned) phenotype
(that grows to over 50 kg) to a distinct blue-finned,
smaller phenotype, this was not tested. In the present
study we thus further examined the dataset of Pinder
et al. (in press), with the following objectives: (1) to
quantify any shift in mahseer community structure
and the current status of both phenotypes; (2) to
identify the vulnerability to extinction of the hump-
backed phenotype in the River Cauvery and the con-
servation implications of the presence of the blue-
finned phenotype; and (3) to present the urgency
associated with defining the true scientific identity of
the ‘hump-backed mahseer’ to advance the ecologi-
cal knowledge required to inform species-specific
conservation action. Note that whilst the 2 mahseer
phenotypes have previously been referenced respec-
tively as T. mussullah and T. khudree, their taxo-
nomic classifications are currently under scrutiny,
and to avoid perpetuating erroneous scientific
names, they are referred to here as only phenotypes,
i.e. as ‘hump-backed’ and ‘blue-finned’, respectively.
Note that the hump-backed phenotype has, histori-
cally, only been recorded from the River Cauvery
basin (Thomas 1873), including its tributaries, the
Kabini (TWFT 1984), Bhavani (Hora 1943) and the
Moyar (Jayaram 1997); and thus, based on its re -
stricted distribution alone, it may be considered as
highly vulnerable to extinction (Helfman 2007, Giam
et al. 2011). By contrast, the blue-finned phenotype
was not recorded in the river prior to 1993 and is
believed to have originated from artificially propa-
gated stock (Desai 2003).
MATERIALS AND METHODS
The study area on the River Cauvery was the Gal-
ibore Fishing Camp, 1 of 4 former angling camps
situated on the River Cauvery encompassed by the
Cauvery Wildlife Sanctuary (an IUCN Category IV
Protected Area) in the state of Karnataka, part of
the Western Ghats in Southern India (Fig. 1).
Between mid-January and mid-March of 1998 to
2012, the Galibore fishery was subject to regulated
angling pressure (maximum 10 rods d−1), practising
a very strict C&R policy. Structured catch data col-
lected during this period included daily records of
individual angler identity (name); hours fished
12

Pinder et al.: Endemic mahseer swimming towards extinction
(effort); number of fish caught; weight of individual
fish (the standard metric used by anglers was impe-
rial pounds [lbs], where 1 lb = 0.45 kg); and notes
relating to mahseer phenotype (denoted as hump-
backed, H; and blue-finned, B). With the exception
of 2 years (1999 and 2000), a sub-sample of catch
returns spanning 1998 to 2012 were available from
the fishery manager and complemented by addi-
tional returns retained by anglers over the same
period. A summary of the data for each year is pre-
sented in Table 1.
While all larger mahseer (>10 lbs
[>4.5 kg]) were typically weighed to the
nearest pound using spring-loaded
weighing scales, many weights for
smaller in dividual fish were found to be
restricted to estimates. Furthermore,
where an angler recorded a large num-
ber of fish during a single (4 h) fishing
session, records were typically limited to
the weight of the largest fish, with the re -
maining catch enumerated, e.g. ‘6 fish to
18 lbs’. Following consultation with the
camp manager and a selection of the
anglers, and as per Pinder et al. (in
press), these data were standardised by
recording 1 fish at 18 lbs with all other
individuals recorded as weighing 5 lbs
(with 5 lbs [2.25 kg] representing the
threshold at which most anglers were
considered to neither weigh nor estimate
the weight of their fish). Where the
weight of the largest individual did not
exceed 5 lbs (either estimated or
weighed), e.g. ‘9 fish to 5 lbs’, data were standard-
ised by applying a 50% weight reduction to the re -
maining 8 fish for which weights were not recorded.
In this example, the adjusted record would account
for 1 fish of 5 lbs and 8 fish of 2.5 lbs. While we
acknowledge the inherent limitations of these stan-
dardised data, the allocation of arbitrary weights (as
guided by the local angling community) has facili-
tated a valuable measure of the numbers of young
fish recruiting to the population over the course of
the study period.
Catch returns were initially sorted into the respec-
tive phenotypes and enumerated as annual totals. To
identify whether the number of blue-finned mahseer
captured each year was a good predictor of the num-
ber of hump-backed mahseer captured, their rela-
tionship was tested using linear regression. To assess
whether the differences in the number of each phe-
notype captured per year were significantly differ-
ent, the gradient of the regression line (b) was used
to test the null hypothesis that equal numbers of the
phenotypes were captured each year, with this
accepted when bwas not significantly different from
1.0 and vice versa, based on its 95% confidence lim-
its. The catch per unit effort (CPUE) of each pheno-
type was then determined for each year and
expressed as the number of each phenotype cap-
tured per hour per year. Differences in CPUE value
between the 2 phenotypes were tested using
ANOVA. The temporal pattern in the CPUE of each
13
Year Total no. Total hours No. of mahseer captured:
of anglers fished Hump-backed Blue-finned
1998 6 580 14 59
2001 9 820 38 153
2002 10 1080 6 81
2003 19 1920 80 148
2004 25 2640 95 342
2005 28 2604 25 407
2006 17 1608 6 228
2007 27 2632 3 452
2008 33 3188 5 1022
2009 11 1196 4 346
2010 29 1984 9 887
2011 35 2388 1 1095
2012 10 980 3 653
Table 1. Temporal resolution of data recovered to determine
catch per unit effort (CPUE) for mahseer. Individual angler
numbers yr−1 (1998−2012) and hours fished (effort) between
January and March in each year are given
Fig. 1. Location of the River Cauvery and the study area in the Western
Ghats of India. The solid line represents the 7 km Galibore fishery (G). The
dashed line represents the 22 km extent of the former catch and release
mahseer fishery; light grey lines show the course of the River Canvery and
its tributaries

Endang Species Res 28: 11–17, 2015
phenotype was tested for significance using linear
regression, where the independent variable was the
number of years since the study commenced and the
dependent variable was the annual CPUE of the
mahseer phenotype. To identify whether there was a
relationship between the temporal patterns in the
CPUE of the hump-backed mahseer and the CPUE of
the blue-finned mahseer, Pearson’s correlation coef-
ficient was used in cross-correlation, using time 0 (i.e.
testing of CPUE data from the same year) and at time
lags of −1 to −3 yr.
For the weight of individual fish, differences be -
tween phenotypes were tested using a Mann-Whit-
ney U-test because the data were not normally dis-
tributed. The temporal pattern in the mean weights
of each phenotype was then tested for significance
using linear regression, where the independent vari-
able was the number of years since the study com-
menced and the dependent variable was the mean
annual weight of the mahseer phenotype. This was
also repeated for all fish captured, i.e. by combining
data from both phenotypes.
Throughout the study, where error is expressed
around the mean, it denotes standard error.
RESULTS
Over the study period, 23 620 h of fishing effort
were applied to C&R of 6162 mahseer, ranging in size
from 1 to 104 lbs (0.45−46.8 kg) in weight. Of these
mahseer, 95% comprised the blue-finned phenotype,
with the remainder being hump-backed (Table 1).
The number of blue-finned and hump-backed mah-
seer captured per year were not significantly related
(R2= 0.14, F1,11 = 1.73, p > 0.05; Fig. 2a) and the slope
of this regression line (b) indicated that significantly
more blue-finned mahseer were captured per year
than hump-backed mahseer (95% confidence inter-
vals: −0.09 to 0.02; Fig. 2a). The annual CPUE of the
blue-finned phenotype was also significantly higher
than that of the hump-backed phenotype (ANOVA:
F1,22 = 21.78, p < 0.01), with the mean CPUE of the
blue-finned phenotype being 0.248 ± 0.050 ind. h−1
and that of the hump-backed phenotype being 0.014
± 0.005 ind. h−1 (Fig. 2b,c). Across the study period,
the CPUE of the blue-finned phenotype significantly
increased with time (Fig. 2b) (R2= 0.70, F1,11 = 25.65,
p < 0.01), whereas it significantly decreased in the
hump-backed phenotype (R2= 0.68, F1,11 = 9.54, p <
0.01; Fig. 2c). The cross-correlation revealed that the
relationship of the annual CPUE of the hump-backed
phenotype was not significantly correlated to the
CPUE of the blue-finned mahseer at time 0, −2 and
−3 yr (r = −0.49, −0.30 and −0.25, respectively, p >
0.05 in all cases), but was significant at time −1 yr
(−0.58, p < 0.05; Fig. 2b,c).
14
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
1998 2000 2002 2004 2006 2008 2010 2012
b
CPUE hump-backed mahseer
(ind. h–1)
CPUE blue-finned mahseer
(ind. h
–1
)
0
200
400
600
800
1000
1200
0 200 400 600 800 1000 1200
a
No. of blue-finned mahseer captured yr–1
No. of hump-backed mahseer
captured yr
–1
0
0.01
0.02
0.03
0.04
0.05
1998 2000 2002 2004 2006 2008 2010 2012
c
Year
Fig. 2. (a) Comparison of the number of each mahseer pheno-
type captured per year (×), where the solid line represents the
fitted relationship (linear regression) and the dashed line repre-
sents the null hypothesis that equal numbers of each phenotype
were captured each year. Annual catch per unit effort (CPUE) of
(b) the blue-finned and (c) hump-backed mahseer across the
study period. Error bars are not displayed for reasons of clarity

Pinder et al.: Endemic mahseer swimming towards extinction
Across the study period, the mean weight of the
hump-backed mahseer was 24.3 ± 1.5 lbs (range:
1−104 lbs [0.45−46.8 kg]) and that of the blue-finned
was 7.8 ± 0.1 lbs (range: 1−62 lbs [0.45−27.9 kg]); this
difference was significant (Mann-Whitney U-test: Z=
−14.37, p < 0.01; Fig. 3). For the hump-backed pheno-
type, mean weights per year significantly in creased
over the study period (R2= 0.45, F1,11 = 8.82, p < 0.02),
ranging between 16 lbs (7.2 kg) in 2001 and 67.5 lbs
(30.4 kg) in 2011 (Fig. 3a). In contrast, the mean
weight of the blue-finned phenotype significantly
decreased over the study period (R2= 0.63, F1,11 =
18.60, p < 0.01), ranging between 13.8 lbs (6.2 kg) in
1998 and 5.4 lbs (2.4 kg) in 2012 (Fig. 3b). Indeed,
across the study period, 42% of the captured blue-
finned phenotype were below 5 lbs (<2.25 kg) in
weight. When the data for both phenotypes were
combined, the highest mean weight of captured fish
was recorded in 1998 (17.7 ± 2.0 lbs; 8.0 ± 0.9 kg) and
the lowest was in 2012 (5.6 ± 0.3 lbs; 2.5 ± 0.1 kg),
with a significant temporal decline in mean weight
also evident (R2= 0.83, F1,11 = 51.71, p < 0.01).
DISCUSSION
The angler catch data revealed some distinct pat-
terns in the composition of the mahseer catches over
time, with a significantly increasing catch rate of the
blue-finned phenotype and a significant decline in
catch rates of the hump-backed phenotype. Despite
considerable technological advances in recreational
fishing gears (e.g. development of braided lines), the
challenging environmental conditions and presence
of sharp submerged rocks in the River Cauvery has
dictated that angling techniques remained consistent
over the period and provided a representative catch
rate of all mahseer between 1 and 104 lbs (0.45–
46.8 kg) (Pinder et al. in press). Hence, these outputs
indicate that the mahseer community of the river is
primarily currently comprised of the blue-finned
phenotype whose mean weight is substantially lower
than that of the hump-backed phenotype. The com-
bination of the significant decline in catch rate of the
hump-backed phenotype and the significant increase
in the sizes of individual fish captured suggests that
there has been a relatively recent issue with their
recruitment in the river, whereas this is not evident in
the blue-finned phenotype.
The recruitment collapse of the hump-backed phe-
notype does not appear to be associated with antago-
nistic interactions between the 2 phenotypes, given
the output of the cross-correlation. It does correspond
with anecdotal reports of the failure of the 2004 mon-
soon (i.e. very low rainfall), which dramatically re -
duced river discharge during the 2005 fishing season
and resulted in the observed mortality of several large
hump-backed mahseer (M. Brown pers. comm.). Their
overall decline was also coincident with an increase
in angling pressure, and although C&R was prac-
tised, it could be speculated that the capture and sub-
sequent handling of some of the large hump-backed
individuals resulted in their post-release mortality
and thus loss from the spawning stock; however,
there is no supporting anecdotal evidence of this.
Irrespective of this, without action to remediate or
mitigate this population decline and recruitment col-
lapse in the hump-backed phenotype, their popula-
15
0
20
40
60
80
100
120
1998
2001
2002
2003
2004
2005
2006
2007
2008
2009
2010
2011
2012
a
0
20
40
60
80
100
120
1998
2001
2002
2003
2004
2005
2006
2007
2008
2009
2010
2011
2012
b
Year
Weight (lb)
Fig. 3. Weight of individual mahseer captured per year
for (a) hump-backed and (b) blue-finned. Filled circles
represent mean annual weight, horizontal lines represent
the 25th, 50th and 75th percentiles, and the error bars
represent the 10th and 90th percentiles. 1 lb = 0.45 kg

Endang Species Res 28: 11–17, 2015
tion in the River Cauvery appears to be increasingly
unsustainable and heading towards extinction.
Historical information, including photographs, is
critical to understand the status of species and popu-
lations (see McClenachan 2009, McClenachan et al.
2012) and reveals that only the hump-backed pheno-
type was captured and photographed during colonial
times. Indeed, photographs of the hump-backed phe-
notype, as typified by its golden body and orange
fins, are distributed throughout the angling literature
and all depict individuals captured in the Cauvery
river system, suggesting the absence of this pheno-
type in other rivers (Thomas 1873, Dhu 1923, MacDo-
nald 1948, Shanmukha 1996). Moreover, until 1993,
it was the only mahseer phenotype captured by
anglers in the Cauvery, suggesting in all probability
that this phenotype is endemic. The appearance of
the blue-finned phenotype is likely to relate to fish
movements and hatchery-reared fish that were initi-
ated in the 1970s. In response to the realisation that a
combination of anthropogenic threats was causing a
rapid decline in mahseer stocks across India, the Tata
Electric Companies (TEC) fish-seed hatchery at Lon-
avla, Maharashtra, began the large-scale breeding
and culture of mahseer species (Tor khudree, T. tor,
T. putitora and the ambiguous ‘T. mussullah’) for
national distribution of fingerlings to augment stocks
(Shanmukha 1996, Sehgal 1999, Ogale 2002, Desai
2003). The dates and geographical details of where
brood-stock was acquired and the seed distribution
of the exact species are scarce, although activities
included the experimental hybridisation between
mahseer species (Ogale & Kulkarni 1987), and the
translocation of species beyond their endemic geo-
graphical ranges (including outside the country) has
been documented (Ogale 2002, Desai 2003). In 1978,
the Trans World Fishing Team (TWFT) visited the
TEC hatchery and provided the first record of blue-
finned mahseer, describing the culture of ‘a strik-
ingly blue-finned fish’, which was targeted for
release in the nearby rivers and reservoirs (TWFT
1984). Sehgal (1999) and Desai (2003) have since
reported the release of 150 000 advanced fry/finger-
lings of T. khudree to the River Cauvery by the
Department of Fisheries of the State of Karnataka,
with further documentation that stocking activity on
the Cauvery included 30 000 mahseer by the Fish
Farmers Development Agency, Mysore (Shanmukha
1996), 15 000 mahseer fingerlings to the Coorg
Wildlife Society and 10 000 to the Wildlife Associa-
tion of South India (Ogale 2002).
The dataset used in the present study reveals that
the blue-finned phenotype was sufficiently well
established in the River Cauvery by 1998 to enable
it to already be captured in greater numbers than
the hump-backed phenotype, with individual speci-
mens attaining weights up to 48 lbs (21.6 kg). Also,
whereas the catch data suggest declines in the
hump-backed phenotype associated with poor
recruitment due to the declining catch rate and
increasing individual fish size, data from the blue-
finned phenotype suggest that sufficient recruitment
occurred to enable large numbers of smaller fish to
be captured by anglers, as 42% of all blue-finned
mahseer captured in the study period were below
5 lbs (<2.25 kg) in weight. Due to the lack of detailed
catch data prior to 1998, records on the blue-finned
phenotype are limited to articles in the popular press
and media. The earliest record communicating their
presence was in 1993 during the mahseer world
angling championships when a fish of approximately
11 lbs (5 kg) was captured (A. Clark pers. comm.).
Based on current knowledge of the growth rates of
the blue-finned phenotype and the demographic
structure of the population by 1998 (see Pinder et al.
in press), it seems highly probable that the blue-
finned phenotype originated from the TEC hatchery
and was introduced during the late 1980s. Under-
standing the ecological mechanisms responsible for
the high population expansion of the blue-finned
phenotype at the expense of the hump-backed phe-
notype in recent years is currently constrained by
insufficient knowledge pertaining to the autecology
and genetics of both phenotypes. However, life his-
tory traits, such as growth, age at maturity and fecun-
dity are considered to be likely factors, with
increased plasticity in the successful utilisation of
key-function habitats (e.g. spawning, feeding) poten-
tially providing the blue-finned mahseer with greater
niche capacity to exploit and thus facilitating com-
petitive displacement. In addition, direct predation
and hybridisation have also been frequently cited as
factors increasing the threat to endemic fishes
through the introduction of new species (Crivelli
1995).
Since the Galibore fishery was closed in 2012, the
fish community has been reported to have been sub-
jected to elevated poaching pressure, but there are
currently no means of measuring and tracking com-
munity and population metrics against the baseline
data established from the current dataset. Accord-
ingly, there is an immediate urgency to establish the
status of the hump-backed mahseer throughout the
Cauvery basin and acquire genetic material to secure
the true taxonomic identity of this animal as a precur-
sor to exploring potential species survival planning.
16

Pinder et al.: Endemic mahseer swimming towards extinction
Acknowledgements. We thank Sportquest Holidays Ltd, D.
Plummer and M. Brown for the provision of catch records.
We are grateful to A. Clarke and M. Clarke of the Trans
World Fishing Team for historical insight into the fishery and
A. Kanagavel for assisting in the production of Fig. 1. This
research was supported by the Mahseer Trust.
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Editorial responsibility: Uwe Krumme,
Rostock, Germany
Submitted: October 13, 2014; Accepted: February 21, 2015
Proofs received from author(s): May 5, 2015
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