Growth of Siberian sturgeon (Acipenser baeri) in the Czech Republic's conditions

The growth of Siberian sturgeon in the conditions of the Czech Republic was monitored at these two localities: a) ponds near Jevany village near the town of Kostelec nad Cernymi lesy in Central Bohemia (49 degrees 59' northern latitude and 14 degrees 51' eastern longitude, altitude 395 m; b) ponds near Rodvinov village, 4 km of Jindrichuv Hradec (49 degrees 09' n, latd. and 15 degrees 00' e. long., altitude 478 m). Two populations of Siberian sturgeon of different age were used as stock fish. The fish were obtained from Mydlovary hatchery (Hluboka nad Vltavou Hatching House, a.s.). Fifty-two individuals of Siberian sturgeon at the age of 90 days were released into Jevany ponds in 1996. The experimental fish rearing terminated in 1999, and the sturgeons were measured and weighed four times in the course of the experiment. Sixty days old Siberian sturgeons were released at two localities in 1997 - 25 individuals into a Jevany pond and 30 individuals into a Rodvinov pond. The Jevany experiment terminated in 1999, and six measurements were carried out in total. In the Rodvinov pond, the fish rearing terminated in 1998, and four measurements were made in total. To evaluate the fish growth, daily weight gains and daily length increments (D.I.), specific weight growth rate (SWGR), specific length growth rate (SLGR) and Fulton's weight coefficient were used. Daily weight gain of the fish in Jevany ponds was 2.41 g, the daily length increment was 0.48 mm. The fish growth in Rodvinov ponds was unusually fast because they achieved their total average weight of 129 g within 65-168 days of age. In Jevany ponds, the largest individual achieved this weight at the age of 362 days. In the second year of the experiment, average daily length increment was 0.70 mm and average daily weight gain amounted to 3.34 g. After three years of fish rearing the total average body length of sturgeons was 719 mm and their body weight 1.73 kg. The values of FWC ranged from 0.3177 to 0.4704 in the rearing period. High mortality was observed in the first 100 days of rearing when the losses amounted to about 30%. Survival in the first two years of sturgeon life was only about 20-30% of all individuals.