FORMATION OF REPLENISHMENT OF BLACK-BACKED SHAD POPULATION (ALOSA KESSLERI KESSLERI (GRIMM, 1887) IN DIFFERENT WATER YEARS BY UNILATERAL (2011, 2013)
Journal Title: Вестник Астраханского государственного технического университета. Серия: Рыбное хозяйство - Year 2014, Vol 0, Issue 2
Abstract
The materials by the volume of discharges and the temperature regime of the water-short in 2011 with the volume of flow for the II quarter – 77.2 km3 and abounding in water 2013 – 125.4 km3 have been analyzed. The period of the researches is from early May to the second fiveday period of late June typical for the mass of producers’ entrances from the sea to the river Volga, to the spawning grounds. Observations for the young fish slope were spent from early June to the end of August. It is shown that while forming a new generation of black-backed shad herring, the major factors limiting the level of reproduction rates are the quantity of producers, the temperature and hydrological regimes of the river Volga (the volume of flow at the spring-summer flood, its du-ration) during the spawning migrations of producers and downstream migration of the young black-backed shad herring at the early stages of the ontogenesis. It is stated that at the different water years the flow of young black-backed shad herring is not the same. So the concentration of the young fish in the catches dramatically increased as a result of inopportune beginning of the spawn-ing temperatures in the water-short period in 2011. The density increased gradually and reached maximum value at the II decade of July in the higher-water 2013. The young of black-backed shad herring rolls down at the early stages of ontogenesis. A short length of downstream migration route from the spawning grounds to feeding areas in the North Caspian, due to the poor hydrological re-gime of the river Volga (low-water in 2011), does not allow the larvae to reach viable stages of the development. The portion of vigorous larvae increased by 10 times in the favorable water years (high-water 2013).
Authors and Affiliations
Olga Pyatikopova, Tatiyana Voinova, Vyacheslav Raspopov
Keywords
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