TY JOUR TI DYNAMICS OF QUALITATIVE COMPOSITION OF THE SPAWNING STOCK OF WHITEFISHES IN THE NORTHERN SOSVA RIVER KW whitefish KW spawning stock KW age and size strucutre KW hydrological conditions JO Vestnik of Astrakhan State Technical University. Series: Fishing industry AU Bogdanov, V.. AU Melnichenko, I.. PY 2015 IS 2015 PB Astrakhan State Technical University