February 15-18, 2009 Washington State Convention Center Seattle ...

CHANGES OF RELATIVE EGG WEIGHT DURING INCUBATION PERIOD OF PERSIAN
STURGEON, Acipenser persicus
Samaneh Poursaeid and Bahram Falahatkar*
Fisheries Department
University of Guilan
Faculty of Natural Resources
Sowmeh Sara
P.O. Box 1144
Guilan, Iran
falahatkar@guilan.ac.ir
The Persian sturgeon, Acipenser persicus, is an anadromous species endemic to the southern water of the Caspian Sea. In recent
years, more studies have been conducted in regards to identification of egg necessity of the Persian sturgeon in incubation
period. After fertilization the chorion of the egg stiffen, that is known as hardening, which serves to protect the developing
embryo also has an important role in fertilization. The egg weight increase, chorion hardening, is a completed mechanism based
on osmotic gradient (Alderdice, 1988) in which the action of different hardening enzymes like transglutaminase (Zotin, 1958),
protease and peroxidase (See Chang-Rak & Ichiro, 1998) are responsible for hardening. The increase in relative egg weight
could be used for evaluation of egg viability, understanding of changes during over-ripening and estimation of the best time
for egg enrichment via some micronutrients solution. Therefore, the aim of present study is to determine egg quality, trends of
relative egg weight, and the peak time of water absorption in Persian sturgeon during incubation period.
Experimental eggs were obtained from 20 females of Persian sturgeon caught from southern parts of the Caspian Sea. Each
female was stripped and coelomic fluid was removed from eggs before insemination. The subsamples were weighed for determination
of the weight of non-water-hardened eggs. Eggs were fertilized with a mixture of sperm from 2 males, checked sperm
activities before fertilization. The average activity of sperm was 85.6 ± 7.3%. Because of stickiness of eggs after fertilization,
silt solution was used according to Kohnehshahri and Azari (1974). Fertilized eggs was rinsed with hatchery water and then
transferred to the Youshchenko incubators for incubation. The eggs were sampled 5 min (after fertilization time), 60 min (after
adhesive removing), 2, 3, 4, 5, 6, and 7 h after fertilization (during incubation). Finally, the number of eggs was counted for
each subsample (1-2g) to calculate the absolute egg weight. Data was analyzed with SPSS software using one-way ANOVA
and Tukey’s as post-hoc test. Data are presented as mean ± S.D.
The results of this study showed that the highest water uptake was observed during 3h after fertilization (AF), whereas no
significant differences was found until 7h AF (P>0.05). Egg weight increased significantly during fertilization and water absorbance
up to 60.6% compare to 3h AF (P