Linear Growth of Sparsely Rakered Whitefish Coregonus lavaretus (Coregonidae) of the Imandra Lake (Murmansk Oblast) / Zubova E. M., Kashulin N. A., Terent’ev P. M. [et al.] // Journal of Ichthyology. – 2016. - Vol. 56, №. 4. - P. 588–599

LINEAR GROWTH OF SPARSELY RAKERED WHITEFISH 593 Table 3. Number of rakers on the first gill arch in different forms ofwhitefish Coregonus lavaretus in the Imandra Lakes Lake Sparsely rakered form Densely rakered form Babinskaya Imandra 22.4 ± 0.2 - 16-28(140) Yokostrovskaya 23.3 ± 0.1 36.2 ± 2.2 Imandra 17-31(458) 31-43(5) Bolshaya Imandra 24.0 ± 0.4 38.8 ± 0.6 20-28(33) 36-42(13) Here and in Table 4, 5: the average value and its error are above the line; the variation range of the parameter is under the line; the number of fish is in the brackets, spc. ning of maturating and full maturity. This gives rise to a more detailed comparative study of growth parame­ ters in the sparsely rakered whitefish throughout its life in the Babinskaya, Yokostrovskaya, and Bolshaya Imandra lakes. The length of an individual is a more stable and convenient parameter than weight (Mina and Klevezal, 1976), and the back calculations of the length are primarily necessary to reduce the error related to the distinctions in seasonal increases of the last year (Zinovyev and Mandritsa, 2003). Linear Growth Rate The dependence between the sizes o f body ( F L ) and scale (Rs) in the whitefish from the three Imandra Lakes is described well by the power regression equa­ tion (Fig. 4). In the logarithmic coordinates, the regression line (the straight line) does not go through the central point of the coordinates, so it is preferable to use the Lee formula for the back calculations (Bryuzgin, 1969; Mina, 1973, 1981). The formulas for the back calculation of fish length are as follows: lnLi = ln37.00 + (lnLn- ln37.00) x (lnRi/lnR„) for the Babinskaya Imandra; lnL,- = ln50.15 + (lnLn - ln50.15) x (ln R i /ln R n) for the Yokostrovskaya Iman­ dra; lnL,- = ln64.33 + (lnLn - ln64.33) x (lnR,/lnR„) for the Bolshaya Imandra. The Lee “phenomenon” is not manifested in the results of the back calculations of length by the regression method. The sex differences in the growth rate were not found. The average values of the calculated length are presented in Table 5. In the whitefish of Northern Fennoscandia, the period of active growth continues from late May to late September or early October (Reshetnikov, 1980; Toi- vonen, 1999). The whitefish samples were collected in the Babinskaya and Bolshaya Imandra lakes from August to October, i.e., the individuals from these lakes had an almost complete scale increase of the cur­ rent year, so we compared the averaged observed esti­ mates of their length with the average calculated esti­ mates for the moment o f the formation of a current- year ring rather than with those calculated for the moment of the formation of a previous one (Fig. 5). The observed length estimate in the whitefish of the Babinskaya Imandra corresponds well to the calcu­ lated one (Fig. 5a), whereas the correspondence of these parameters is less pronounced in the whitefish of the Bolshaya Imandra, which may be due to a larger length increase in the current year than in the previous one (Fig. 5c). In the Yokostrovskaya Imandra, the whitefish was caught from June to May (approxi- Fig. 4. Dependence of the body length (FL) on the length of the frontal diagonal radius of scale (Rs, 1 ocular micrometer unit = 0.1 mm) in the sparsely rakered whitefish Coregonus lavaretus in the Imandra Lakes: ( - ♦ - ) Babinskaya Imandra, FL = 37.00R^'60, R2 = 0.78; ( - □ - ) Yokostrovskaya Imandra, FL = 50.15R°'52, R2= 0.77; ( - ■- ) Bolshaya Imandra, FL = 64.33R°'52, R2 = 0.74. JOURNAL OF ICHTHYOLOGY Vol. 56 No. 4 2016