Population dynamics of
the Hill Stream Loach Acanthocobitis mooreh(Sykes, 1839) (Cypriniformes: Nemacheilidae)
from northern Western Ghats of India
Sanjay S. Kharat1 & Neelesh Dahanukar2
1 Department of Zoology, Modern
College of Arts, Science and Commerce, Ganeshkhind,
Pune, Maharashtra 411007, India
2 Indian Institute of Science Education and Research, SaiTrinity, Garware Circle, Pune, Maharashtra 411021,
India
2 Zoo Outreach Organization,
96, Kumudam Nagar, VillankurichiRoad, Coimbatore, Tamil Nadu 641035, India
1 kharat.sanjay@gmail.com, 2 n.dahanukar@iiserpune.ac.in
(corresponding author)
doi: http://dx.doi.org/10.11609/JoTT.o3301.4562-8 | ZooBank:urn:lsid:zoobank.org:pub:22FE53F0-A8A1-453E-BE19-09EDCBEC0E8E
Editor: Davor Zanella, University of Zagreb, Zagreb,
Croatia. Date
of publication: 26 July 2013 (online & print)
Manuscript details: Ms #
o3301 | Received 11 August 2012 | Final received 25 April 2013 | Finally
accepted 29 June 2013
Citation: Kharat,
S.S. & N. Dahanukar (2013). Population
dynamics of the Hill Stream Loach Acanthocobitis mooreh (Sykes, 1839) (Cypriniformes:Nemacheilidae) from northern Western Ghats of India. Journal of Threatened Taxa 5(11): 4562–4568; http://dx.doi.org/10.11609/JoTT.o3301.4562-8
Copyright: © Kharat& Dahanukar 2013. Creative
Commons Attribution 3.0 Unported License. JoTT allows unrestricted use of this article in any medium,
reproduction and distribution by providing adequate credit to the authors and
the source of publication.
Funding: None.
Competing Interest: None.
Acknowledgements: We
are thankful to an anonymous reviewer for critical comments on the earlier
draft of the manuscript.
Abstract: We have studied the sex ratio, length-weight relationship,
growth pattern and mortality of a hill stream loach, Acanthocobitis mooreh (Sykes, 1839), from its type locality in
northern Western Ghats of India. The sex ratio of A. mooreh was unbiased
and did not deviate from the expected 1:1 ratio. The power of the length-weight
relationship of A. mooreh for both males and
females and for the combined population was significantly lesser than the cubic
value expected by isometry. Von BertalanffyGrowth Function fitted to the length frequency data suggested that the
asymptotic length of the fish is 6.04cm while the growth constant is 0.79y-1. Total mortality of the fish is 2.05y-1and the young are more prone to mortality. Both, the high growth rate and high mortality at younger ages indicates
that the fish is ‘r’ selected.
Keywords: Growth function, length-weight relationship, sex ratio.
The publication of this article is
supported by the Critical Ecosystem Partnership Fund (CEPF), a joint initiative
of l’Agence Française de Développement, Conservation International, the
European Commission, the Global Environment Facility, the Government of
Japan, the MacArthur Foundation and the World Bank.
For figures, images, tables -- click here
Acanthocobitis mooreh was originally described as Cobitis mooreh by
Sykes (1839) from Mula-Mutha River of Pune. Because of its remarkable similarity
with Acanthocobitis botia,A. mooreh has often been confused as its
junior synonym. However, A. mooreh can be distinguished from A. botia by incomplete lateral line as opposed to complete
lateral line in A. botia (Menon,
1987). There is some debate
regarding the correct generic status of this species and it has often been put
under Noemacheilus (Menon,
1987), Nemacheilus (Talwar& Jhingran, 1991) and Acanthocobitis(Jayaram, 2010). Currently, the species is recognized as Acanthocobitis mooreh in Eschmeyer(2013).
Acanthocobitis mooreh is endemic to peninsular
India (Jayaram 2010) and is common in the upper
reaches of the Krishna River system. Some information on the reproductive biology and allometricrelationships between different growth and reproduction related body parameters of A. mooreh isavailable (Kharat 2001; Kharatet al. 2008). However, not much
information is available on the population dynamics of this species. Such information is also relatively rare
on loaches, especially from India. Since the information on the population dynamics can aid in
understanding the basic ecology of the species and also help in the
conservation action (Raghavan et al. 2011; Prasad et
al. 2012), in the present study we document the population dynamics, including
sex ratio, length-weight relationship and growth and mortality patterns in A.mooreh collected from its type locality in Pune,
northern Western Ghats of India.
Methods
Specimens of Acanthocobitis moorehwere collected from Mula-Mutha River, a tributary of
Krishna River system, in Pune (18.5210N & 73.8570E,
elevation 557m), Maharashtra, India (Image 1) from local fishermen and fish
markets. The fish were collected as
target fish by the fishermen using dragnet in shallow
to waist deep waters with muddy, sandy or pebbly river bed, which is the
habitat of the fish. The fish were
collected each month for a period of one year and were preserved in 4%
formaldehyde. Number
of male and female individuals collected every month are given in Table
1.
The standard length of the
fish was measured using dial calipers with a least count of 0.1mm. The weight of each individual was
measured on an electronic weighing balance with a least count of 0.01g. The sex of the fish
was determined by dissecting the fish and identifying the gonads. We used chi-square test to test the null
hypothesis that the sex ratio is 1:1. Bonferroni correction was used when applying
chi-square test for multiple comparisons. We plotted length and weight of the fish to determine the power of the
length-weight relationship W = aLb,
where W is the weight, a is the
normalization constant, L is the length and b is the scaling
power. The null hypothesis that b= 3 was tested using t test as described by Zar(1999, pp. 342). To test whether
the power b, calculated as a slope of the log-log plot for weight and
length, was different for males and females, we used t test as described
by Zar (1999, pp. 362).
Data were arranged in a
length frequency table with 0.25cm as the smallest midlengthand 0.5cm class interval. A contour
plot was prepared to understand the distribution of length classes in relation
to different months. Growth and
mortality parameters, as well as exploitation levels were estimated from the
length frequency data using FAO–ICLARM Stock Assessment Tools II (FiSAT II) software (Gayanilo et
al. 2005). Asymptotic length (L∞) and growth constant (K)
of von Bertalanffy Growth Formula (VBGF) were
estimated using ELEFAN 1 method (Pauly 1984). Based
on L∞ and K values, the growth performance index (ø’= 2 * log L∞ + log K) and potential longevity (3/K)
of fish were estimated for different sites (Pauly& Munro 1984). Total mortality
(Z) was estimated from length converted catch curve. Natural mortality (M)
was determined using Pauly’s M equation, which
works well, especially for tropical fish, ln(M) = -0.0152–0.279 ln(Lα)
+ 0.6543 ln(K) + 0.463 ln(T),
where, T is the average annual temperature, which is 260C. Fishing mortality (F) was
calculated as F = Z-M and the current exploitation level (E)
was calculated as E = F/Z (Pauly1984).
Result and Discussion
Sex ratio
We collected 373 individuals
of Acanthocobitis moorehout of which 185 were males and 188 were females. The male to female sex ratio was 1:1.02
(Table 1) and it was not significantly different from 1:1 (2 = 0.02, P = 0.8766). The monthly sex ratio, except for
January and October, did not differ significantly from 1:1 (Table 1). Female bias in October was not
significantly different from the expected 1:1 ratio when Bonferronicorrection was applied and significance was tested at a=0.004167. Bias towards
the male individuals in January, however, was significant even after Bonferroni correction and is likely to be a sampling bias
rather than a true skew. Thus, we
suggest that the sex ratio of Acanthocobitis mooreh does not deviate much from the expected
1:1 ratio.
Even though 1:1 sex ratio has
also been observed in some other loaches such as Sabanejewia balcanica (Zanella et
al. 2008) and Cobitis simplicispina(Ekmekçi & Akan 2003) in many other loach species
such as Cobitis sp. (Kostrzewaet al. 2003), Cobitis calderoni(Valladolid & Przybylski 2008), Cobitis ohridana(Bohlen et al. 2003), Cobitis narentana (Zanella et al.
2003) and Cobitis tanenia(Marconato & Rasotto1989; Boroń et al. 2008) the sex ratio is often
biased towards more female dominated populations. In fact, in Cobitis tanenia the male:female sex ratio can sometimes escalate up to 1:22
(Bohlen & Ritterbusch 2000). Many factors including temperature
dependent sex determination, presence of hormone analogue in the environment,
sex selected mortality due to predation, intersexual differences in life span
or behavior, evolution of hermaphrodism and
polyploidy sperm parasitism (Bohlen & Ritterbusch2000 and references mentioned within) have been suggested as driving forces for
the biased sex ratio. Since Acanthocobitis mooreh showed more or less consistent unbiased sex
ratio throughout the year, it is possible that no such external factors affect
the A. mooreh population in the study area.
Length-weight relationship
Power b of the
length-weight relationship of Acanthocobitis mooreh for the pooled data was 2.8143 (SE =
0.0539) while for males and females it was 2.8135 (SE = 0.0718) and 2.7899 (SE
= 0.0808) respectively (Fig. 1). In
all the cases the observed values of power b was significantly different
than cubic value expected by isometry (pooled: t =
-3.4418, df = 371, P = 0.0006; male: t= -2.5970, df = 176, P = 0.0102;
female: t = -2.6021, df = 192, P= 0.01). Thus, the null hypothesis
of an isometric relationship was rejected and it can be said that the power of
the length-weight relationship in A. mooreh is
significantly lesser than an isometric cubic value. Further, the value of bwas not significantly different for males and females (t = 0.2185, df = 368, P = 0.8272).
Our value of b for the
pooled data is slightly higher than the value determined by Kharatet al. (2008) for Acanthocobitis mooreh. However, in both the cases it could be established that the power bin A. mooreh is significantly lesser than
3. In the case of other loaches it
is shown that the value of power b for the pooled data is either close
to 3 (Ekmekçi & Akan 2003; Sánchez-Carmona et al.
2008; Valladolid & Przybylski 2008) or often more
than 3 (Rita Kumari & Nair 1978; Marconato & Rasotto 1989, Harka et al. 2002; Dhakal & Subba 2003; Sánchez–Carmona et al. 2008). It is suggested that the power bin length-weight relationship of fish differ according to the species, sex,
age, season, ontogenic changes, fish feeding, number
of specimens examined, differences in the observed length ranges of the
specimens caught and additive effect of variation in gonad weight during
various stages of sexual maturity (Türkmen et al.
2001; Moutopoulos & Stergiou2002; Peck et al. 2005; Froese 2006; Kharat et al. 2008). Less than cubic value of the power in the case of A. mooreh could also be an effect of stress response as a
part of habitat decline in this area.
Growth
Distribution
of length frequencies across the months are shown in Fig. 2a. Most of
the population was observed between 3–6 cm standard length and the length
rarely exceeded 6cm standard length. Highest frequency of large-sized specimens was observed during February
and September (Fig. 2a). This
coincides with the spawning period of Acanthocobitis mooreh (Kharat 2001; Kharat et al. 2008). It has been shown that A. mooreh spawns
twice in a year, once between February/March and again between August/September
(Kharat 2001; Kharat et al.
2008). We fitted the von Bertalanffy Growth Formula to the length frequency data
(Fig. 2b) and the Rn values depicting goodness
of fit for the growth curve was 0.359. Asymptotic length approached about 6cm standard length (Table 2), which
is consistent with our observations where the large-sized fish only seldom
crossed 6cm standard length.
In all the loaches studied so
far, including Sabanejewia balcanica (Zanella et al.
2008), S. aurata (Harkaet al. 2002), Cobitis sp. (Kostrzewaet al. 2003), C. ohridana (Bohlen et al.
2003), C. simplicispina (Ekmekçi& Akan 2003) and Barbatula zetensis (Bohlen et al. 2003), the growth constant (K)
is much lower than that for A. mooreh. Coupled with the fact that A. mooreh also has a much smaller asymptotic length, it
can be said that A. mooreh grows very rapidly
towards maturity.
Mortality
We used length converted
catch curve (Fig. 3a) to determine various mortality related parameters (Table
3) and plotting of length structured virtual population analysis (Fig. 3b). A. mooreh has a very high natural mortality rate of 2.05y-1and with the fishing mortality of 0.26y-1 the total mortality (Z) ofA. mooreh is 2.31y-1 (Table 2). This is much higher than that reported
for another loach Sabanejewia aurata (Harka et al.
2002). For A. mooreh, natural mortality was higher during the early
age groups and it decreased with the size of the fish while the fishing
mortality increased with the size (Fig. 3b). A. mooreh is often caught by tribal people in this
area and are sold in local fish markets. The fishing mortality of the fish is very low at 0.26y-1 with
the exploitation rate of 0.13 indicating that fishing is not a threat to the
populations of A. mooreh. The fact that A. moorehhas a high growth rate (Table 2) and high mortality in the young age (Fig. 3b),
indicates that the species is ‘r’ selected.
Conclusion
Even though Acanthocobitis mooreh has
been assessed as Least Concern species in IUCN Redlist,
owing to its wide distribution and absence of any recognizable wide spread
threat to the species, it has been pointed out that some of the populations of
the species are facing threats because of pollution of water bodies and loss of
habitat (Raghavan & Ali 2011). Especially in the current study area
increase in the extent of urbanization has severely threatened the population
of the species. The population of
the species, which was once considered as abundant in Pune urban area (Kharat et al. 2001), has declined drastically in the recent
past and has become fragmented because of habitat modifications, recreational
activities and levels of pollution in different stretches of the river. Such threats are known for other
populations of A. mooreh as well (Dahanukar et al. 2012; Kharat et
al. 2012). Since, any conservation
action plan targeted towards the species could be a futile exercise in the
absence of knowledge about the ecology of the species, we believe that the
current study will contribute significantly to our knowledge about the ecology
of A. mooreh and may also provide insights
about the ecology of loaches of the Western Ghats in general.
REFERENCES
Bohlen, J., V. Šlechtová, R. Šanda, L.Kalous, J. Freyhof, J. Vukic & D. Mrdak (2003). Cobitis ohridanaand Barbatula zetensisin the River Morača Basin, Montenegro:
distribution, habitat, population structure and conservation needs. Folia Biologica (Kraków)51: 147–153.
Bohlen, J. & D. Ritterbusch (2000). Which factors affect sex ratio of spined loach (genus Cobitis)
in Lake Müggelsee? Environmental Biology of Fishes59: 347–352; http://dx.doi.org/10.1023/A:1007695703991
Boroń, A., I. Jeleń,
D. Juchno, M. Przybylski& E. Borzuchowska (2008). Age and growth of the karyologically identified spinedloach Cobitis taenia(Teleostei, Cobitidae) from
a diploid population. Folia Zoologica57(1–2): 155–161.
Dahanukar, N., M. Paingankar,
R.N. Raut & S.S. Kharat(2012). Fish fauna of Indrayani River, northern
Western Ghats, India. Journal of Threatened Taxa 4(1):
2310–2317; http://dx.doi.org/10.11609/JoTT.o2771.2310-7
Dhakal, A. & B.R. Subba (2003). Length-weight relationship ofLepidocephalichthys gunteaof Pathri Khola, Morang
District. Our Nature 1: 53–57.
Ekmekçi, F.G. & F.E. Akan (2003). Preliminary
data on growth and reproduction of Cobitis simplicispina from Turkey. Folia Biologica (Kraków) 51:
183–186.
Eschmeyer, W.N.
(2013). Catalog of Fishes electronic version.
http://research.calacademy.org/ichthyology/catalog/fishcatmain.asp. Online
version dated 25 March 2013. Accessed on 12 April 2013.
Froese, R. (2006). Cube law, condition factor
and weight–length relationships: history, meta-analysis and
recommendations. Journal of Applied Ichthyology 22: 241–253; http://dx.doi.org/10.1111/j.1439-0426.2006.00805.x
Gayanilo, F.C. Jr., P. Sparre & D. Pauly (2005). FAO-ICLARM Stock
Assessment Tools II (FiSAT II). User’s
Guide. FAO Computerized Information Series (Fisheries) No. 8. FAO, Rome, 168pp.
Harka, Á., K. Györe& P. Lengyel (2002). Growth of
the golden spined loach Sabanejewia aurata (Filippi, 1865)
in River Tisza (Eastern Hungary). Tiscia 33: 45–49.
Jayaram, K.C. (2010). The
Freshwater Fishes of the Indian Region. Second Edition. NarendraPublishing House, Delhi, 616pp.
Kharat, S.S. (2001). Study of reproductive biology of Nemacheilus moreh (Sykes). PhD Thesis. Submitted to
Dr. Babasaheb Ambedkar Marathwada University, Aurangabad, India.
Kharat, S.S., N. Dahanukar & R. Raut (2001). Decline of
freshwater fish of Pune urban area. Journal of Ecological Society13/14: 46–51.
Kharat, S.S., Y.K. Khillare & N. Dahanukar(2008). Allometricscaling in growth and reproduction of a freshwater loach Nemacheilus mooreh (Sykes, 1839). Electronic
Journal of Ichthyology 4(1): 8–17.
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; http://dx.doi.org/10.11609/JoTT.o2796.2644-52
Kostrzewa, J., M. Przybylski,
L. Marsza & M. Valladolid (2003). Growth and
reproductive biology of loaches Cobitis sp. in
Lake Lucieñ, Poland. Folia Biology (Kraków) 51(Suppl.): 179–182.
Marconato, A. & M.B. Rasotto (1989). The biology of a population of spined loach, Cobitis taenia L. Italian Journal of Zoology56(1): 73–80; http://dx.doi.org/10.1080/11250008909355624
Menon, A.G.K. (1987). The
Fauna of India and Adjacent Countries, Pisces, Vol 4,Teleostei-Cobitoidea, Part 1, Homalopteridae. Zoological Survey of India, Kolkata, 259pp.
Moutopoulos, D.K. & K.I. Stergiou (2002). Length–weight and length–length
relationships of fish species from the Aegean Sea (Greece). Journal of
Applied Ichthyology 18: 200–203; http://dx.doi.org/10.1046/j.1439–0426.2002.00281.x
Pauly, D. (1984). Fish
population dynamics in tropical waters: a manual for use with programmable
calculators. ICLARM Studies and Reviews 8:
1–325.
Pauly, D. & J.L. Munro (1984). Once more
on the comparison of growth in fish and invertebrate. ICLARM Fishbyte 2(1): 21.
Peck, M.A., C. Clemmesen & J.P. Herrmann (2005). Ontogenic changes in the allometric scaling of the mass and length relationship in Sprattus sprattus. Journal of Fish Biology 66: 882–887; http://dx.doi.org/10.1111/j.0022–1112.2005.00651.x
Prasad,
G., A. Ali, M. Harikrishnan & R. Raghavan (2012). Population
dynamics of an endemic and threatened Yellow Catfish Horabagrus brachysoma (Günther)
from Periyar River, southern Western Ghats, India. Journal of Threatened
Taxa 4(2): 2333–2342; http://dx.doi.org/10.11609/JoTT.o2590.2333-42
Rita Kumari,
S.D. & N. B. Nair (1978). Length-weight relationship of the loaches Noemacheilus triangularisDay and Lepidocephalus thermalis(Cuv. & Val.). Matsya 4: 52–58.
Raghavan, R. & A. Ali (2011). Nemacheilus mooreh. In: IUCN 2012. IUCN Red
List of Threatened Species. Version 2012.2. <www.iucnredlist.org>.
Downloaded on 19 April 2013.
Raghavan, R., A. Ali, N. Dahanukar & A. Rosser (2011). Is the fishery for the DeccanMahseer, Tor khudree(Sykes, 1839) in the Western Ghats Hotspot sustainable? A
participatory approach to stock assessment. Fisheries Research110: 29–38; http://dx.doi.org/10.1016/j.fishres.2011.03.008
Sánchez-Carmona,
R., L. Encina, A. Rodríguez-Ruíz& V. Rodriguez-Sánchez (2008). Age, growth and diet of the
Iberian loach, Cobitis paludicain two different environments. Folia Zoologica 57(4): 420–434.
Sykes, W.H. (1839). On the
fishes of the Deccan. Proceedings of the General
Meetings for Scientific Business of the Zoological Society of London 6:
157–165.
Talwar, P.K. & A.G. Jhingran (1991). Inland Fishes of India and
Adjacent Countries. Oxford-IBH Publishing Co. Pvt.
Ltd., New Delhi, 1158pp.
Türkmen, M., O. Erdoan, H. Hallolu& A. Yildirim (2001). Age, growth and reproduction
of Acanthalburnus microlepis,Filippi 1863 from the YaganRegion of the Aras River, Turkey. Turkish Journal of Zoology 25:
127–133.
Valladolid,
M. & M. Przybylski (2008). Life
history traits of the endangered Iberian loach Cobitis calderoni in the River Lozoya,
Central Spain. Folia Zoologica57(1–2): 147–154.
Zanella, D., M. Markovčič,
D. Schneider, P. Mustafič, M. Čaleta & I. Radič(2003). Growth of Cobitis narentana Karaman, 1928 in
the Neretva River, Croatia. FoliaBiologica (Kraków) 51:
155–157.
Zanella, D., M. Mrakovčić,
P. Mustafić, M. Ćaleta,
I. Buj, Z. Marčić,
S. Zrnčić & J. Razlog-Grlica(2008). Age and growth of Sabanejewia balcanica in the Rijeka River, central Croatia. Folia Zoologica 57(1–2):
162–167.
Zar, J.H. (1999). Biostatistical Analysis -
Fourth Edition. Pearson Education, India, 662pp.