GROWTH OF PIKE (ESOX-LUCIUS) LARVAE AND JUVENILES IN THE MUSOV-RESERVOIR

The results of research are presented dealing with the dynamics and seasonality of the growth of young pike (Esox lucius L.) in the upper Musov Reservoir (Nove Mlyny man-made lake system, Southern Moravia, Czech Republic) during 1981, 1982 and 1985. The growth was expressed and mutually compared by means of polynomic curves. The relationships between different types of measured lengths and the length-weight relationship were analysed by means of linear and geometric regressions. A high growth intensity was found in pike fry during the spring and summer periods and the mean relative increments of total length fluctuated in successive months from 1.43 to 1.85 mm . d-1. During the autumn period the growth rate slowed down and reached only 0.33 mm . d-1 in October. The mean total length reached 257.3 mm at the end of October. An evident mutual relation was found between the degree of morphological development, ecology and ethology of the fry during two periods with distinct changes of the growth rate, occurring at total lengths of 20 and 45-50 mm. The growth patterns of the pike fry, compared with other species studied on the same locality (pike-perch, perch, roach, rudd), was characterized by a much higher growth rate and longer growth season.