Length-weight relationship of  J. osseus indicated an allometric form of growth. Seasonal variations in the condition offish could not be attributed to any particular facto

Baragi, M Vijayakumar

James, P S B R

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Reprinted from Indian Journal of Marine Sciences Vol. 9. Number 1. March 80. pp. 67-68 Length-Weight Relationship & Condition Factor of the Sciaenid Fish, Johnieops osseus (Day) VlJAYAKUMAR M BARAGI & P s B R JAMES' Univer~ty of Agricultural Sciences, College of Fisheries. Mangalore 575002 Received 15 March 1979; revised received 6 August 1979 Length-weight relationship of J. osseus indicated an allometric form of growth. Seasonal variations in the condition offish could not be attributed to any particular factor. The present observations, which form a part of the general study of the biology of Johnieops osseus (the most abundant sciaenid of the South Kanara coast) deal with the length~weight relationship and condition factor, the information on which is meagre l - 3 . Total length and weight of 1539 fishes of all sizes, collected from trawl landings at Mangalore and Malpe during 1976-77 were recorded. Length and weight were plotted in the form of a scatter to note the relationship between the two. This suggests a relationship of the form, Y=A +BX, where Y= log W, A = log a, B=b and X = log L. The values of A and B were estimated by the method of least squares. The length-weight relationship, computed from the above equation, for the 2 sexes at each of the locality is Mangalore-females: log W = - 5.3097 + 3.1877 log L; males: log W= - 5.2294+3.1497 log Land Malpe-females: log W = -5.1201 +3.1071 log L: males: log W = - 5.0059 + 3.0468 log L. Analysis of covariance applied to test the difference in the values of B, for the 2 sexes at the 2 localities showed no significant difference at 5% level. Since difference was also not seen between the values of B obtained for the 2 localities, a common regression equation of log W= -5.2341 +3.1540 log L was obtained for the 2 places. The t test 4 , used to test the pattern of growth, indicated an allometric form of growth. 1 he relative condition factor K" = ; was obtained for individual fishes. Mean values of K" for each month were calculated for immature (irrespective of sex) and mature males and females. The weighted average for the above, were also calculated. There was no difference in the condition of fish of both the sexes at • Present address: Mandapa m Regional Centre of Central Marine Fisherie~ Research 'Institute. P. O. Marine FIsheries 623510 Mandapam Camp MANGAlORE IoIAlES MALPE /' ,,----A 1"'",AtURE • ,}~ "f'l/\ ~/\/ \},' - ,----- ~, . z ~ !·U2 Q l'UO ~ U 1).118 ~ 0-96 ~ Q'~ tJ< 0·82 L-:,--:,:-c,C--;'o --:,---;'o:--c,C-!c, -+., --L~,---:,:-o!c--c,---;,o:--C,C-,!--:', MONTHS Fig. I-Variation in relative condition factor of J. osseus at Mangalorc and Malpe I either of the localities. But the condition of immature fishes was lower than that of the mature fishes. Data on seasonal vari~tion in condition of fish (Fig. I) show that in October, December and January, both immature and mature fishes show a high condition indicating that maturity and spawning may not be the factors responsible. Based on the available data, it is difficult to explain the monthly variations in the condition of fish. Blackburn' remarked that it is not possible to interpret the changes of condition in Thyrsites atun basing on sexual cycle or the intake of food and that it may depend on several other factors. The same opinion is also held by James6 in the case of Eupleurogrammus intermedius. However, Thompson 7 has pointed out that high and low condition in Pleuronectes plaressa I are found before and after spawning. Hickling' has attributed the low and high condition in Sardina pilchardus as due to sexual cycle and availability of food respectively. I The authors thank Pro!. H.P.C. Shetty, Director of , Instruction for facilities. References 1 Kutty M N. J mar bioI Ass India, 9 (1968) 197. 2 Rao K Venkatasubba, Indian J Fish, 10 (1968) 413. 3 Rajan S, indian J Fish. 11 (1968) 639. 4 Snedecor G W. Sw!islical Jechods applied co experiments in Clgriculture and biology (Allied Pacific 'Private Ltd , Bombay) 1961 .485. '-5 Blackburn M. Aust J Mar Freshwater Res, 2 (1960) 14. 6 James P S B R. The ribbon-fishes ofthejamily Trichuridae of India, Memoir, 1 (Marine Biological Association of India ) 1967. 226. 7 Thompson D A W. On growth and form (University Press Cambridge) 1943. 794. 8 Hickling C f. J mar bioi An U K.16 \1945) 115 . • 

Length-weight relationship and condition factor of the Sciaenid fish, Johnieops osseus (Day)

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Length-weight relationship and condition factor of the Sciaenid fish, Johnieops osseus (Day)

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