Studies on fecundity and Gonadosomatic index of Schizothorax plagiostomus (Cypriniformes: Cyprinidae)

 

Muneera Jan 1, Ulfat Jan 2& G. Mustafa Shah 3

 

1,2,3 P.G. Department of Zoology, University of Kashmir, Hazratbal, Srinagar, Jammu & Kashmir 190006, India

1 janmuneera@ymail.com (corresponding author), 2 ulfatjan@yahoo.com,3 gmustafashah@yahoo.com

 

 

 

Abstract: The present investigation deals with the assessment of fecundity and gonadosomatic index (GSI) of Schizothorax plagiostomuscollected from the river Jhelum, Kashmir. The mean value of fecundity was estimated as 14599 (SD 9219.7) eggs with a mean total length of 34.340 (SD 6.86) and a mean total body weight of 440.60 (SD267.62). The relationship of fecundity with other parameters such as total length, total weight, ovary length and ovary weight were found to be linear and the value of correlation coefficient (r) was 0.965, 0.961, 0.933 and 0.972 respectively. The highest value of GSI was recorded in the month of May 12.56 (SD1.81).

 

Keywords: Allometricrelationship, fecundity, spawning season, Schizothorax plagiostomus.

 

 

doi: http://dx.doi.org/10.11609/JoTT.o3269.5375-9 | ZooBank: urn:lsid:zoobank.org:pub:F21EC3E7-EB48-4204-88AE-6484DF9298FC

 

Editor: Neelesh Dahanukar, IISER, Pune, India.    Date of publication:26 January 2014 (online & print)

 

Manuscript details: Ms # o3269 | Received 26 July 2012 | Final received 18 November 2013 | Finally accepted 07 December 2013

 

Citation: Jan, M., U. Jan & G.M. Shah (2014).Studies on fecundity and Gonadosomatic index of Schizothorax plagiostomus(Cypriniformes: Cyprinidae). Journal of Threatened Taxa6(1): 5375–5379; http://dx.doi.org/10.11609/JoTT.o3269.5375-9

 

Copyright: © Jan et al. 2014. 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: The first author is a PhD research scholar registered in P.G. Department of Zoology, University of Kashmir. This study was supported only by departmental research grant.

 

Competing Interest:The authors declare no competing interests.

 

 

 

For figures, tables -- click here

 

 

Understanding reproductive behaviour of fishes is not only important for elucidating the basic biology of the fishes but it can also help in their management and conservation.  The term ‘fecundity’ denotes the egg laying capacity of a fish or the number of ripe eggs produced by a fish in one spawning season.  Knowledge of fecundity is also an important aspect in stock size assessment, stock discrimination (Holden & Raitt 1974) and rational utilization of stock (Morales 1991) and in explaining the variation of population as well as to make efforts for increasing the amount of fish yield.  Thus, studies on reproduction behavior (fecundity) of fish are important and a basic requirement for improvement of and effective fishery resources management and conservation (Marshall et al. 2003; Grandcourt et al. 2009).

Schizothorax plagiostomus Heckel,is one of the most important commercial food fishes of Kashmir.  But the decline of Schizothorax population in the water bodies of Kashmir is taking place due to many factors especially habitat destruction, over fishing, competition for food and breeding grounds from exotic carps, water pollution, etc.  These complex factors have altered the landscape and water flow which in turn have reduced the fish stock in water bodies by affecting fish migration, spawning and nursing grounds. The present study is aimed to determine the fecundity and its relation with total body length, total body weight, ovary length & ovary weight) which are useful in increasing the yield of fish species, stock management and assessment in any water body.  Hence, the present study will be useful in understanding the relationship of fecundity with above mentioned body parameters and thus serve as a tool for better management of this resource.

 

Materials and Methods

Fishes for the present study were procured from three different sites of the river Jhelum (74–750E & 33.5-–34.50N)—Zero bridge, Chattabal and Kadalbal pampore—using cast net, every month.  For fecundity estimation 30 specimens were collected and analysed and for GSI estimation 5 fish specimens were collected 3 times in a month. The study was carried from November 2010 to October 2011.  After noting down morphometric parameters (body length and body weight) of the fishes in fresh conditions, mature gravid fishes were dissected.  The ovaries were removed and wiped with blotting paper to remove moisture and then preserved in 5% formalin solution for 24 hours so that the eggs would swell up for easy calculations.  The fecundity of the fish was calculated using the gravimetric method (Simpson 1959) as well as the volumetric method (Kandler & Pirwitz 1957).  The total number of eggs per gonad was obtained, i.e., absolute fecundity of fish.  Relative fecundity was determined by the ratio of total number of eggs per unit weight or length of fish.  Its relation with various body parameters such as body length, body weight, ovarylength and ovary weight was determined by using log transformation of power law,

Y = aXb

i.e., Log Y = log a + b log x

Gonadosomatic index (GSI) expressed according to de Vlaming(1982) method for assessing the development of gonads and was calculated as:

 GSI = Gonad weight/body weight *100.

 

Results

Ovary structure: The ovaries of Schizothorax plagiostomus was a bilobedfleshy structure occupying a large part of the abdominal cavity.  The two lobes of the ovary were almost uniform in size.  The middle portion of the ovary was broader than the anterior and posterior region.  The eggs were fully ripe and yellowish in color in the mature ovary.  It has been found that the shape, size, and color change in different stages of maturity.

Relationship between fecundity (F) and total length (Tl): Table 1 provides data for the two variables i.e, fecundity and total length..According to it the number of ova varied from 3437 for a fish of length 26.2cm to 34800 for a fish of length 45.3cm. The relationship between fecundity and the total length can be expressed as:

Log F = -0.976 + 3.30 log TL

Where F= fecundity and TL= total length in cm.

The number of eggs contained was more or less directly proportional to the total length of the fish body. The regression equation was found to be linear (Fig. 1). The correlation coefficient (r) was 0.96 (p<0.001) which corresponds to a very strong positive correlation and is highly significant.

Relationship between fecundity (f) and total body weight (bw): Table 1 provide data for fecundity and total body weight. The number of ova varied from 3437 for a fish of weight 176.5g to 34800 in the fish weighing 1150g.The relationship between fecundity and the total body weight can be expressed as:

logF = 1.26 + 1.09 logBW

Where F= fecundity and BW =body weight.

The relationship between fecundity and total body weight was found to be linear and highly significant with the correlation coefficient (r) equal to 0.961 (Fig. 2).

Relationship between fecundity (f) and ovary weight (ow): Table 1 provide data for the two variablesi.e, fecundity and ovary weight. The weight of ovary ranged from 10.11g to 120g in fish weighing 176.5g to 1150g. Fecundity varied from 3437 in an ovary of weight  176.5g to 34800 in the ovary weighing 1150g.The relationship between fecundity and the ovary weight (Fig. 3) can be expressed as:

logF = 2.69 + 0.917 logOW.

Where F= fecundity and OW = ovary weight.

Regression analysis showed that there is a significant relationship (p<0.01) between the numberof eggs in the ovary i.e., fecundity and the weight of ovary.  The number of eggs per female increased with increasing ovary weight. The correlation coefficient was found to be 0.972.

Relationship between fecundity (f) and ovary length (ol): Table 1 provides data for fecundity and ovary length.  The ovary length ranged from 9.4–22.8 cm in fish ranging from 25.2–45.3 cm. The number of ova varied from 3437 to 34800 in fish ranging in length from 26.2–45.3 cm.  The relationship between fecundity and ovary length (Fig. 4) can be expressed as:

logF = 1.45 + 2.37 logOV.

Where F= fecundity and OL = ovary length.

A significant linear relationship was observed between fecundity and the ovary length, i.e., fecundity increased with the ovary length.  The correlation coefficient(r) was found to be 0.933.

Length weight relationship: Table 1 provide data for two variables, i.e., total length and total weight of fish. The data showed a positive correlation between the two variables. Fig. 5 shows relationship between these two variables. The correlation coefficient was found to be 0.992. The relationship between total fish length and total body weight can be expressed as:

Log BW = 2.9781 TL - 1.9819 (SE=0.0315; P<0.05).

Where BW = body weight,  TL = total length and SE = standard error.

Gonadosomatic Index (GSI): The GSI value ranged from 1.87 to 12.66. The maximum GSI value 12.56 was found in the month of May while minimum value 1.87 was obtained in the month of July.GSI exhibited variation in different months of the year (Fig. 6).  The GSI value decreased during may to July which suggests that the fish has completely spawned.

 

Discussion

Fecundity has been defined as the number of ripening eggs prior to spawning (Bagenal 1978) and is a main factor governing the size of a year class of a population.  Nikolskii(1965) stated that “fecundity is a specific feature that arises during the evolution of a new species adapted to a certain environment and is directed towards the continuance of the species”.

In the present study, the number of eggs was found to increase linearly with the increase in total length, body weight, ovary length and ovary weight.  These findings are supported  by the findings of previous workers, Jhingran (1968), Raina(1977), Pathani (1981), Sunder (1984), Islam & Hossain (1990), Hussain et al. (2003), Mohan (2005), Offem et al. (2008), Bahuguna & Khatri(2009).  All the relationships between fecundity and total length, body weight, ovarylength and ovary weight found to be highly significant (p< 0.005).  Significant relationships between fecundity and these variables were also reported by Das & Singh (1969), Hussain et al. (2003), Bahuguna& Khatri (2009), Alam & Pathak(2010).

The value of correlation coefficient ‘r’ in the present study indicate that among the above four parameters studied, closest correlation of fecundity was observed with the ovary weight (r=0.972) followed by total body length (r=0.966), body weight(r=0.961) and total ovary length (r=0.933).  Similar results were reported by Bahuguna& Khatri (2009).

Length weight relationship of this fish species  is in accordance with the model of LeCren (1951).  It was observed that fish shows allometric pattern of growth (b<3).  Similar results were reported by Goel et al (2011) for schizothorax richardsonii and by Sundar (1985) for schizothorax curvifrons.  It was also observed that fecundity varies with fish size and it generally increase with increase in body weight and body length.

The gonadosomaticindex (GSI) was found in range from 1.87 to 12.56   in this study.  The maximum GSI value was found in the month of May (12.56) which indicated the maximum gonadal growth.  A sharp drop in the GSI value had taken place in July (1.87) which might have been caused by spawning.  The fish thus spawn during spring season although the gonads were fully mature in the winter season but in a dormant phase because of severe winter and spawned only on return of favorable exteroceptivefactors in spring season (Malhotra 1970; Jyoti et al 1972; Sunder 1984).

 

 

References

 

Alam, M. & J.K. Pathak(2010). Assessment of fecundity and gonadosomatic index of commercially important fish, Labeo rohitafrom Ram Ganga River. International Journal of Pharma and Biosciences 1(3): 1–6.

Bagenal, T.B. (1978). Aspects of fish fecundity, pp. 75–101. Shelby D. Gerkind (ed.). Ecology of Freshwater Fish Production. Blackwell Scientific Publications, 520pp.

Bahuguna, S.N. & S. Khatri(2009). Studies on fecundity of a hill stream loach Noemacheilus montanus(Mc Clelland) in relation to total length, total weight, ovary length and ovary weight. Our Nature 7: 116–121.

Das, S.M. & H. Singh (1969).Studies on the comparative fecundity of five Kashmir fishes. Kashmir Science 4(1–2): 77–88.

de Vlaming, V.L. (1982). The effects of temperature and photoperiod on reproductive cycling in the estuarine gobiid fish (Gillichthysmirabilis). Fish Bulletin 73: 1137–1157.

Goel, C., B. Ashoktaru, P. Veena, A. Shahnawaz& K. Rohit (2011). Length-weight relationship of Snow Trout (Schizothorax richardsonii) Based on Linear and Nonlinear Models from Hill Stream of Uttarakhand, India.World. Journal of Fish and Marine Sciences 3: 485–488.

Grandcourt, E.M., T.Z. Al-Abdessalaam, F. Francis, A.T. Al-shamsi & S.A. Hartmann (2009). Reproductive biology and implications for management of the Orange-spotted Grouper Epinephelus coioides in the southern Arabian gulf. Journal of Fish Biology 74: 820–841; http://dx.doi.org/10.1111/j.1095-8649.2008.02163.x

Holden, M.J & D.F.S. Raitt (1974). Manual of fisheries science part 2: methods of resource investigation and application. FAO Fish Technical Paper 115 Rev. 1: 1–214.

Hussain, L., M.A. Alam, M.S. Islam & M.A. Bapary (2003). Estimation of fecundity and gonadosomaticindex (GSI) to detect the peak spawning season of Dhela (Osteobrama cotio cotio). Pakistan Journal of Biological Sciences 6(3): 231–233.

Islam, M.S. & M.A. Hossain (1990). The fecundity and sex ratio of the common punti Puntius stigma (cypriniformes: cyprinidae). Univ. J. Zool. Rajshahi Univ. 9: 69–74.

Jhingran, V.G. (1968). Synopsis of Biological Datd on Catla catla (Hamilton). FAO Fisheries Synopsis (32), 100pp.

Jyoti, M.K. (1973).Studies on the feeding and gonadal cycles of some fishes of Jammu and Kashmir state. PhD Thesis. University of Jammu, 242pp.

Kandler, R. & W. Pirwitz(1957). Uber die fruchbarkeit der plattfische in Nor dsee-Ostsee. Raum. Kleler Meeresjorseh 13(1): 11–34.

Mohan, M. (2005). Spawning biology of snow trout, Schizothorax richardsonii(gray) from River Gaula (Kumaon, Himalayas). Indian Journal of Fisheries 52(4): 451–457.

Malhotra, Y.R. (1965). Seasonal variation in the morphology of the ovaries of a kashmir fish schizothorax niger Heckel. Kashmir Science 2: 27–39.

Malhotra, Y.R. (1970).Studies on the seasonal changes in the ovary of Schizothorax niger Heckel from Dal Lake in Kashmir. Japanese Journal of Ichthyology 17(3): 110–116.

Marshall, C.T., L. O’Brian J. Tomkiewiez, F.W. Koster, G. Kraus, G. Markinsdottir, M.J. Morgan, F. Saborido-ray, J.L. Blanchard, D.H. Secor, P.J. Wright, N.V. Mukhina& H. Bjornsson (2003). Developing alternative indices of reproductive potential for use in fisheries management, case studies for stocks spawning, an information gradient. Journal of Northwest Atlantic Fisheries Society33: 161–190.

Morales, D.A. (1991). La Tilapia en Mexico. Biologia, Cultivoy Pesquerias. A G Editor S.A., 190pp.

Nikolskii, G. (1965) Theory of Fish Population dynamics as the biological background for rational exploitation and management of fishery resources. Nauka, Moscow.

Offem, B.O., Y.A. Samsons& I.T. Omoniyi (2008). Reproductive aspects of common freshwater fishes in the cross river, Nigeria. The Journal of Animal and Plant Sciences 18(4): 130–138.

Pathani, S.S. (1981). Fecundity of Mahseer Tor putitora. Proceedings of Indian Academic Sciences (Animal Science) 90(2): 253–260.

Raina, H.S. (1977).Observations on the fecundity and spawning behavior of Schizothorax esocinus Heckel, from Dal lake, Kashmir. Indian Journal of Fisheries 24: 201–203.

Sunder, S. (1984). Studies on the maturation and spawning ofSchizothorax curvifrons Heckel from River Jhelum,Kashmir. Journal of the Indian Institue of Science 65(c): 41–51.

Sundar, S. (1985). Length-weight relationship of S. curvifrons Heckel from Jhelum, Srinagar. Geobiosnew reports 4: 16–19.

Simpson, A.C. (1959). Methods used for separating and counting the eggs in fecundity studies on the Plaice (Pleuronectes platessa) and Herring (Clupea herengus): Occasional Paper. FAO,Indo-Pacific Fish. Coun.no. 59112.

Qadri, M.Y., S. Mir & A.R. Yousuf (1983). Breeding biology of schizothorax richardsonii (Gray and Hard).Journal of the Indian Institue of Science 64: 73–81.