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International Journal of Aquaculture, 2015, Vol.5, No.1 1
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5
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Although the fecundity of
A. immaculata
is increasing
with the fish length and weight (Raikova-Petrova et al.,
2013) we have established that the fecundity declines
with increasing the temp of growth. This inverse
correlation is due to the faster temp of growth of the
younger individuals, which however have a lower
fecundity. According to Roff (1992), Saborido-Rey
and Kjesbu (2005)
the reproductive effort reduces the
fish growth, which is the reason to decrease the
fecundity.
The values of K
f
greater than 1 or very close to 1 are
indication for the "well-being" of the population
(Fulton, 1902). In our previous study the value of K
f
was calculated as 1.22 (calculations were made with
the total weight of the individuals) (Rozdina et al.,
2013). The received values for the condition factor for
males (1.05) are the same or very close to the one for
the populations studied in Marmara sea – 1.05
(Ergüden et al., 2007) and Turkish part of the Black
sea – 1,02 (Samsun, 1995). The condition factor for
the females and the both sexes in the Sea of Marmara
(1.1 and 1.08 respectively) and the Turkish part of the
Black sea (1.21 and 1.12 respectively) are higher than
the received values by us. This difference is due to the
spawning migration of the Pontic shad in Danube
River. During the migration from the sea to the river
the fish cease the feeding, spend a lot of energy to
reach the spawning sites and lose weight. This
inevitably reduces the fish condition. Kolarov (1965)
reports significant changes in the condition of Pontic
shad during its migrations in the river. The decrease in
the condition of the fishes is due to the feeding
termination.
The process of gonad deve lopment and eggs
production requires a lot of energy. A lot of the
deposited fats are utilized for egg production (Okafor
et al., 2011, Oso et al., 2011). This is the reason for
increasing the fish fecundity with decreasing the
condition.
Authors' Contributions
DR participated in the design of the study, statistical analysis
and drafted the manuscript. GR conceived of the study,
participated in its design and helped with the statistical analysis
and to draft the manuscript. PM and SV were involved in the
laboratory samples and the primary data procession. All of the
authors red and approved the final manuscript.
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