BIOMETRY OF THE MAHSEER TOR TOR (HAMILTON)

This kind of study is very much essential for solving the race problem of the species. Regarding the race problem Zupanovic (1968) stated, "As it is essential to be able to distinguish between different species, so it is essential to distinguish between the self perpetuating sub-groups within th species. These sub-groups may be equivalent to what taxonomists call sub-species, but they are presumably more generally of lesser rank. In the fIShery literature, they are often called races or populations" f

constant value to the determined, 'b' is the regression coefficient and 'X' the standard length. The correlation coefficient '~' of these regressions was computed.

RESULTS AND DISCUSSION
The morphometric ehara,cters showed a proportional positive increase with increase in length of the fish. The mean and range of these values have been ~sented in Table I. Among the meristic characterS (fable m the number of pectoral rms rays and 1ateralline scales showed variations without any relation to length of the fish. The number of other meristic characters were constant

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The regression coefficient 'b' (Table III) of different variable characters (y) on standard length (X) indicates that the rate of growth in respect to standard length is highest in case of tota1length (b = 1.3283) and lowest in case of eye diameter (b = 0.0335) High values of correlation coefficient 'r' (Table III) obtained indicates a high degree of positive correlation of the different morphometric parameters with the reference length (standard length).   Biomettic Index of T tor (Fig. 1) iildicates that the eye diameter becomes progressively smaller in relation to head length. A similar case has been reported by Tobm (1974) in case of Lates niloticus. The growth of head length and girth in relation to total length and gape in relation to head length w~ almost constant. According to Bayagbona (1963) a constant index in any of the biometric characters in relation to its reference length is isometric. The growth of inter-orbital distance in relation to head length was found to be allometric and showed wide variations.
The morphomebic ratios and meristic counts in T tor observed in the present study, were found to be quite similar to that observed by earlier workers (McClelland, 1839;Hora, 1940 a, c;Hamilton, 1822).
Considerable difference in the morphometric characters has been observed between males and females ( Table I). The males were found to have greater height of dorsal, pectoral and pelvic fins than the females. On the other hand the females had greater height of anal rm. greater length of free margin of dorsal rm, greater eye diameter and rnaxilary barbel length and also the predorsallength, snout length and gape were greater.
Nikolsky (1963) stated that males and females often differ in the length and shape of the fins. According to him, in the males of many Cyprinoids, both the" paired and the unpaired fins are slightly larger than the females. He cited examples of some species where males were found to differ in shape of the fins. For example in the males of certain lake baikal Sculpins, Colio comephorus, the thoracic fins were found to be significandy larger. He further stated that in Xiphophorus (Fam. PoecUidae) there is' a long outgrowth on the caudal fin, whereas in the males of many pleuronectids of the family Bothidae, the rays of the dorsal rm are elongated, and so on. In majority of cases the difference between the structure of the fins in males and females is connected with the peculierities of reproduction, as for example, th",dorsal fin which is larger in male than in the female of the grayling, Thymallus, and increases still further towards the time of spawning, creates a turbulence close to te spawning fish during the spawning. process, and delays the dispersal of the spenn by fast currents (Brown, 1938). The larger size of the pelvic fins of the male Tinch facilitates a more successful fertilization of the eggs and their attachment to plant stalks (Nikolsky, 1963). Hence such a difference in the morphometric characters of males and females may be represented as sexually dimolphic chamcters.
According to Gould (1966) ratios between morphological characters of fish will not necessarily be constant for the organisms of the same species due to varlilton resulting from differences in sex, race and nutrition and/or other environmental factors.
Various authors have shown that morphometric characters of fish can vary under the influence of environment 'and in particular the thennal factor during the period of incubation and the beginning of 1arvallife (Schmidt, 1921;Barlow, 1961). According to Hubbs (1922) and Taning (1944) variation occurs in the nwner of rays in the unpaired fins in several species which is also related to an adaptation to movement of water of various density.
Variations in the body proportions in the same species according to hydrographic conditions have also been recorded by various authors (Hubbs, 1922;Barlow, 1961).
They associated these variations with the effect of the duration of periods of growth and of the relating diffrentiations which detennine the number of vertebrae and of segments.

SUMMARY
Morphometric and meristic characters of T tor (Hamilton) have been analysed. The morphometric characters of the species showed a proportional positive growth with the increasing length of the fish and a high degree of positive correlation with the reference length. Some of the meristic characters were found to be constant while some varied without showing any relation to the length of the fish. The biometric index indicated that the growth of head length, girth and gape is isometric while the growth of interorbital distance is allometric. The eye diameter becomes progressively smaller in relation to head length. Some difference has been observed between male and female of the species.