Особенности воспроизводства балтийского шпрота в 1971-1985 гг.
The article has first considered the regularities governing the Baltic sprat year classes' abundances at early stages of ontogenesis. The impact of variations in the heat-loving zooplankton productivity, the temperature regime and predators loading upon the sprat year classes' formation has been shown. The periods of a high sprat abundance are well related with warm years, the northward expansion of the spawning and feeding areas, the high amounts of eggs and larvae and the heat-loving zooplankton (Temora, Centropages, Bosmina), and with the low cod stock abundance. The low level of sprat reproduction is noted in cold years when the terms and spawning areas are shortened, the food availability of larvae and fingerlings is poor due to the decreased heat-loving zooplankton amount, as well as in the years of the intensified inflow of the North Sea water followed by an increased cod abundance. Predation-induced decline in the sprat amount is well expressed in the spawning areas. According to the regression analysis, the sprat year classes abundances in the years 1971-1985 were defined by the cod predation, 26.88 %, the spawning stock abundance, 20.69 %, the winter phosphorus concentration, 17.43 %, the sprat larvae abundance in May, 9.98 %, and by the amount of Nauplii in May, 4.67 %. The sum of these factors is 79.65 % at p ≥ 0.95.
| Main Authors: | , , |
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| Format: | Journal Contribution biblioteca |
| Language: | Russian |
| Published: |
1987
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| Subjects: | Baltic sprat, Baltic cod, Year-class strength, ASFA_2015::P::Population abundance (in number), ASFA_2015::I::Ichthyoplankton, ASFA_2015::S::Spawning grounds, ASFA_2015::F::Fish larvae, ASFA_2015::F::Fish eggs, |
| Online Access: | http://hdl.handle.net/1834/9894 |
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