Effects of Various Hormones on the Sexual Maturity of European Eel (Anguilla Anguilla L.) Females from Farm and Lakes
Previously described and alternative methods of the induction of sexual maturation in the European eel were investigated. Weekly administrations of a gonadoliberin agonist (GnRH-A=D-Phe6-GnRH-Ea) did not induce statistically significant effect on the gonads of treated eels in none of the dosages used (0.1 μg and 10 μg/fish). Carp pituitary extract and carp pituitary extract together with a dopamine antagonist caused considerable external changes (increase in eye size) and significant gonadal development in two treatment groups: wild and cultivated stocks. The induction of the ovulation by double amount of CP and gonadoliberin agonist with dopamine antagonist mixture was not successful in a wild stock. Fertilisation of stripped eggs of farm eel was attempted unsuccessfully in, due to low egg quality. An advanced phase of the sexual maturation process could be induced in specimen infected by Anguillicola crassus indicating, that nematode infection is not a limiting factor in the artificial propagation of the European eel.
KeywordsEel artificial maturation Anguillicola crassus hormonal treatment
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We would like to thank to Mr. Ferenc Németh, Mr. István Szabó, Mr. István Báthory for catching trial eels from Lake Balaton, Mr. Ákos Lukács Köröm eel farm and Mr. Lazaros Natzis DELI, Greece for providing the experimental fish. We are very grateful to the Pathology Department of the Keszthely Hospital for the histological slices. We also thank to Dr. Ferenc Müller (Institute of Toxicology and Genetics, Karlsruhe), who reviewed and corrected the manuscript. This work was supported by the Ministry of Education (BIO-169/2001 and OM-00440/2001).
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