Present address: Fisheries Promotion and Infrastructure Division, Agriculture and Fisheries Department, Miyazaki Prefecture, Miyazaki 880-8501, Japan.
Differences in self-feeding activity between thermally selected and normal strains of rainbow trout Oncorhynchus mykiss at high temperatures
Article first published online: 31 MAR 2008
© 2008 Japanese Society of Fisheries Science
Volume 74, Issue 2, pages 372–379, April 2008
How to Cite
INENO, T., ENDO, M. and WATABE, S. (2008), Differences in self-feeding activity between thermally selected and normal strains of rainbow trout Oncorhynchus mykiss at high temperatures. Fisheries Science, 74: 372–379. doi: 10.1111/j.1444-2906.2008.01534.x
- Issue published online: 31 MAR 2008
- Article first published online: 31 MAR 2008
- Received 27 March 2007. Accepted 2 November 2007.
- demand feeding;
- high temperature breeding;
- Oncorhynchus mykiss;
- rainbow trout;
- thermal tolerance
ABSTRACT: Feeding activity was examined at high temperatures by using a demand feeder for thermally selected and normal rainbow trout Oncorhynchus mykiss strains. When the water temperature was raised in experiment 1 from 17.5 to 25.7°C at 0.3°C/day in 21 days, the average daily food consumption rate in the thermally selected strain rose to 7.1%, which was significantly higher than that of the normal strain (4.1%, P < 0.05). The corresponding rate was also significantly higher in the thermally selected (0.8%) than in the normal strain (0.2%, P < 0.05) of fish in experiment 2 where water temperature was raised to 24.1°C in 0.5°C/day increments. When water temperature was raised rapidly in experiment 3 from 16.7 to 21.7°C in one day and gradually to 24.4°C in 28 days at 0.1°C/day, the average daily food consumption rates were 1.0 and 0.1% for the thermally selected and normal strains, respectively, with significant difference (P < 0.01). These results suggest that the thermally selected strain has acquired thermal tolerance as a result of artificial selection.