Behavioural response of juvenile Chinook salmon Oncorhynchus tshawytscha during a sudden temperature increase and implications for survival

Abstract

· Juvenile Chinook salmon Oncorhynchus tshawytscha survival and behaviour were evaluated during a temperature increase from 8.8 to 23.2 °C. · Relatively little mortality (12%) occurred, which was unexpected. · The percent of fish with an active swimming behaviour increased from 26% to 93% and opercular beat rates increased from 76 to 159 beats per minute. · Although sublethal in the laboratory, thermal stress was likely incurred by juvenile salmon in this study and the associated behavioural changes may increase predation potential in the wild.