Panagiotis A. Pantazis a *, Tomas Policar b, Miroslav Blecha b
a * Department of Ichthyology, Aquatic Fauna and Fish Diseases, Faculty of Veterinary Medicine, School of Health Sciences, University of Thessaly, 224 Trikalon Street, P.O.Box 199, Gr-43100, Karditsa, Greece
Tel +30 24410 66020, Fax +30 24410 66045, e-mail: ppantazis@vet.uth.gr
b Faculty of Fisheries and Protection of Waters, South Bohemian Research Centre of Aquaculture and Biodiversity of Hydrocenoses, University of South Bohemia in Ceske Budejovice, Zatisi 728/II, 38925, Vodnany, Czech Republic.
Introduction
Northern and Central Europe has started the commercial exploitation of new freshwater species (Perca fluviatilis & Sander lucioperca). In Switzerland, freshwater river perch is sold at a retail price of 30€-35€/kg. In Denmark, pikeperch is sold at a retail price of 12€-15€/kg while the fresh fillets are sold at a retail price of 14€-18€/kg. In Netherlands, pikeperch fresh fillets are sold at a retail price of 19€-28€/kg. In Austria, pikeperch frozen fillets are sold at a retail price of 40€/kg. The annual consumption of river perch fillets in Switzerland amounts to 6.000-7.000 tons of which only 10% are produced locally. The annual consumption of fresh pikeperch in Denmark amounts to 800-900 tons of which only 30% is landed locally and the rest is imported.
Materials and Methods
This project has been realized at the installations of the Research Institute of Fish Culture and Hydrobiology, Faculty of Fisheries and Protection of Waters, University of South Bohemia, Czech Republic. Ten pairs of males (Average Weight 1,0kg) and females (A.W. 0,75kg) of Sander Lucioperca L. have been submitted to temperature (6ο C à 16ο C) and photoperiod control (8L: 16D à 16 L: 8D) for a four month period.
The first week of the fifth month, females have been injected with HCG (550IU / kg).
Egg-laying took place in the same tanks where broodstock has been kept, on special artificial substrates. After ovulation, broodstock has been removed and eggs remained in the same tanks till the "eye-stage".
Results and Discussion
Ovulation took place 75-90 Degree-Days (DD) after the HCG injection. Hatching took place after 60-80 DD after ovulation. The fertilization % (fertilization rate) ranged from 45- 83%, while the egg diameter ranged from 1,133±0,0197mm to 1,185±0,0093mm.
The length of newly-hatched larvae ranged from 3,35 mm to 3,64 mm, while the 2-day larvae had lengths from 3,95 mm to 4,16 mm. The number of 2-day larvae produced per gram of female broodstock has been between 10 to 85 larvae.
The osmotic shock (20g of NaCl + 1 liter of water) in the 2-day larvae has indicated their satisfactory physiological and ontogenetic condition, considering that the mortality of the larvae within a period of 30min to 60min has accounted to 5% of the total number of larvae which undertook the osmotic shock.
Conclusion
This experiment has indicated the ability of Sander Lucioperca L. to survive in captivity and reproduce successfully after been submitted to temperature, photoperiod and hormonal (HCG) control.