Možnosti zvýšení adaptability a prevence negativních změn v chování u násady jesetera sibiřského (Acipenser baerii)

The experiment was performed to assess the impact of a modification in feed technology in the intensive rearing of Siberian sturgeon (Acipenser baerii) on the fish behavior. Four feeding regimes were tested in three repetitions: surface feeding during the day (DFSF), surface feeding at night (NFSF), bottom feeding during the day (DFBF), bottom feeding at night (NFBF). Sturgeon behavior was recorded using a video system in experimental observation tank before the application of different feeding regimens at 48th days post-hatching (dph) and every 20 days therafter (68th, 88th and 108th dph). In addition, the effect of five and ten-day starvation on fish behavior was determinated. Five parameters were tested: the total time spent in the lowest 10 and 25 % of the observation tank, the total time spent in the uppermost 10 and 25 % of the observation tank and the total activity. The whole experiment including larval rearing lasted 100 days and videos were analyzed using MATLAB software. Statistical differences were observed among the tested groups during our experiment. Experimental group NFBF at 88th dph showed the highest spending time in the lowest 25 % of the tank. Furthermore, NFBF at 68th and 88th dph displayed the lowest spending time in the uppermost 25 % of tank (only NFSF was not significantly different from NFBF at 68th dph). No statistical differences were observed in the uppermost or the lowest 10 % of the tank after all-day videorecording. After starvation, some differences were observed among the groups, however no clear trend or continuity with the data obtained before the starvation were found. In conclusion, the tested group NFBF showed better preconditions for intensive rearing of sturgeons, which might be subsequently stocked in open waters due to the lowest movement in the uppermost part of the tank (68th and 88th dph) than other tested groups. This could increase survival of the fish in the wild due to lower predation risk