Stress, pain and welfare of fish

Abstract

The first experimental Chapter of the thesis (Chapter 2) looked at the effect of contestant size on aggression in rainbow trout (Oncorhynchus mykiss) before, during and after feeding. Results from this Chapter provided evidence of mutual assessment in rainbow trout, provided evidence of higher levels of aggression in homogenous pairs of fish, and illustrated that aggression in heterogenous pairs of trout was absent until the addition of a resource (food).

The second experimental Chapter of the thesis (Chapter 3) looked at the effect of feeding levels and group size on the behaviour of farmed rainbow trout. Results from this Chapter provided evidence of reduced aggression levels at higher food densities, provided evidence of increased aggression levels in smaller group sizes, and illustrated that group size has less of an effect on behaviour when food is more readily available.

The third experimental Chapter of the thesis (Chapter 4) looked at trade offs between feeding and shock avoidance in the goldfish. Results from this Chapter provided evidence of an emotional experience of pain in the goldfish, illustrated by the trade off between shock avoidance and feeding. The first experiment illustrated an increasing tendency to avoid an area of a tank where shock stimuli and food where simultaneously given, and this avoidance increased with shock strength. The second experiment illustrated a trade off in the fish. Fish were more likely to enter the shock zone to feed as food deprivation period increased. This strongly suggested that the goldfish were centrally processing pain, as the motivation to avoid the noxious stimuli was traded off against the motivational drive to feed.

Finally, the results from all Chapters were discussed and potential further research was suggested in Chapter 5.

Date of Award	Jul 2010
Original language	English
Awarding Institution	Queen's University Belfast
Sponsors	Department of Agriculture, Environment and Rural Affairs
Supervisor	Jaimie Thomas Allan Dick (Supervisor) & Peter Laming (Supervisor)