4.7. Erratic behaviours
Behavioural responses to stress such as darting and flashing are
considered a tertiary stress response, as opposed to primary responses
such as increases in catecholamines and cortisol, or secondary
responses such as changes in plasma glucose and lactate. However,
avoidance behaviours are immediate and transitory, and similarly
involve darting and flashing. As noted above, the majority of fish
maintained position or circled slowly such that darting and flashing
were minimal except during sampling. However, fish returned to their
previous states within several minutes once sampling was finished,
suggesting a minimal expression of avoidance behaviours, a conclusion
consistent with the physiological data. The physical activity of
darting and flashing may be associated with elevated plasma lactate
and potassium concentrations [72,88], but here, neither parameter
changed over the entire transport process.We assumed that each time
a load was added, the smolts that were already in the hold were
disturbed. However, smolts had resumed schooling by the time
loading from each truck was completed and the physiological data
support recovery at dockside during loading.