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| Author(s): |
Alexsandra Carmen Caseiro
Total Authors: 1
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| Document type: | Master's Dissertation |
| Press: | Piracicaba. |
| Institution: | Universidade de São Paulo (USP). Escola Superior de Agricultura Luiz de Queiroz (ESALA/BC) |
| Defense date: | 2001-01-29 |
| Advisor: | Jose Eurico Possebon Cyrino |
| Abstract | |
The importance of live fish transportation is frequently underestimated by fish culturists. The high mortality of fingerlings during and after transportation adds to the production costs and diminishes the profits during production of fingerlings and food fish. The present work has focused on the strategies to improve the success of Iive transportation of Nile tilapia (Oreochromis niloticus) fingerlings. Two experiments evaluated the effect of fastening fish previously to transportation and the benefits of using benzocaine as an anesthethic on the water quality, duration of transport and fish survival. In both experiments fish were stocked into 8-L plastic bags with 1,5L of declorinated water tempered with salt at 3g/L. After fish were loaded, the bags were filled with oxygen to a volume of 8L and sealed with rubber bands. Dissolved oxygen (DO), water temperature, pH, carbon dioxide (C02), total ammonia nitrogen (N-NH3total) and unionized ammonia nitrogen (N-NH3) were monitored. Fish mortality during and after the trial was also recorded. In the first experiment 4.5 to 6.0g Nile tilapia fingerlings, non-fasted or fasted for 48 hour previous to transportation, were stocked into the bags at a rate of 175g of fish/L of water. Water quality parameters were monitored at 4, 8, 12, 16 and 20 hours from the beginning of the experiment. The water in the bags with fasted fish had higher DO levels and lower C0<sub<2, NH3total) and NH3 compared to water from bags with non-fasted fish (P<0.05). Such differences were maintained along the time (P<0.05). There was a significant interaction between time of transport and fish condition for all the water quality parameters, but water pH. Water with non-fasted fish had a faster decline in 0D and accumulated more C02 and NH3total compared to water with fasted fish. Water NH3, temperature and pH showed great variation in bags containing fasted fish. In the second experiment, the effects of benzocaine on the water quality were evaluated during live transportation of 5g tilapia fingerlings in plastic bags. Fish were fasted 72 hours prior to the study and were loaded into 8-L plastic bags at 235 or 470g of fish/L of water. Benzocaine was tested at 10 or 20mg/L. Control treatments without the use of benzocaine were set for both fish loads. Significant differences on the time of transport and water DO, CO2, NH<sub3total and NH3 were observed between the two fish loads tested (P<0.05). The benzocaine had no influence on the water quality parameters, except for the trend of reducing the NH3total in the water with the increase in the doses of benzocaine for the higher fish loads (P<0.05).The high leveis of carbon dioxide in the water (131mg/L to 207mg/L) may have effected a tranquilizing action on fish, masking the effects of using benzocaine. (AU) | |