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Master's Dissertation
DOI
https://doi.org/10.11606/D.11.2019.tde-20191218-174144
Document
Author
Full name
Alexsandra Carmen Caseiro
E-mail
Institute/School/College
Knowledge Area
Date of Defense
Published
Piracicaba, 2000
Supervisor
Title in Portuguese
Qualidade da água no transporte de alevinos de tilápia do Nilo (Oreochromis niloticus) em sacos plásticos
Keywords in Portuguese
ALEVINOS
EMBALAGENS PLÁSTICAS
QUALIDADE DA ÁGUA
TILÁPIA-DO-NILO
TRANSPORTE
Abstract in Portuguese
Apesar de ser uma operação de extrema importância, o transporte de peixes vivos é frequentemente negligenciado em muitas pisciculturas. A alta mortalidade de alevinos durante e após o transporte contribuem para o aumento dos custos de produção e diminuição dos lucros das piscigranjas produtoras de alevinos ou dedicadas a recria e engorda. A presente dissertação avaliou estratégias auxiliares no transporte de alevinos de tilapia (O. niloticus), espécie de grande interesse comercial no Brasil e no mundo. Em dois experimentos foram avaliados o efeito do jejum e do uso do anestésico benzocaína sobre a qualidade da água, duração do transporte e a sobrevivência dos peixes durante e após o transporte. Os peixes foram estocados em embalagens plásticas de 8 litros, contendo 1,5L de água (sem cloro e com 0,3% de sal), as quais tiveram seu volume completado com oxigênio. Em ambos os experimentos foram monitorados o oxigênio dissolvido (OD), a temperatura da água, o pH, a concentração de gás carbônico (CO2), de amônia total (NH3total) e de amônia não-ionizada (NH3). A sobrevivência dos peixes durante e após o transporte foi registrada. No primeiro estudo, alevinos de tilápia do Nilo (O. niloticus) de 4,5 a 6,0g, alimentados ou submetidos a um jejum de 48 horas, foram estocados nas embalagens a uma carga fixa de 175g/L. Os parâmetros de qualidade da água acima mencionados foram mensurados às 4, 8, 12, 16 e 20 horas do início do experimento. Nas embalagens com peixes em jejum o oxigênio foi maior e houve um menor acúmulo de CO2, NH3total e NH3 na água, comparadas as embalagens com peixes alimentados (P<0,05). Nos 5 intervalos de tempo avaliados, foram observadas diferenças significativas em todos estes parâmetros (P<0,05). A interação entre o tempo de transporte e a condição alimentar dos peixes foi significativa (P<0,05) para todas as variáveis de qualidade de água, exceto para o pH. No segundo experimento foram avaliados os efeitos de três doses de benzocaína (0,10 e 20 mg/L) e duas cargas de peixes (235 e 470g/L) sobre a qualidade da água e a duração do transporte de alevinos de tilápia do Nilo (O. niloticus), de 4,4, a 5,0 g. Foram obesrvadas diferenças significativas no tempo de transporte, OD, CO2, NH3total e NH3 entre as cargas de peixes (P<0,05), mas não entre as doses de benzocaína avaliadas (P>0,05), a não der pela tendência de redução nos níveis de NH3total na água do transporte com o aumento das doses de anestésico para a maior carga de peixe (P<0,05). Os elevados níveis de CO2 na água do transporte (131 mg/L a 207mg/L) podem ter exercido ação tranquilizante nos peixes, mascarando os efeitos do uso da benzocaína.
Title in English
Water quality during live transportation of Nile tilapia (Oreochromis niloticus) fingerlings in plastic bags.
Abstract in English
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, 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 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.
 
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Publishing Date
2019-12-19
 
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