Quantitative analysis and modelling of the behavioural dynamics of Salvelinus fontinalis (brook trout)

Behavioural sequences of juvenile brook trout Salvelinus fontinalis were investigated by time-lapse video-recording in the laboratory. A repertoire of six behavioural states was considered. Time-dependent probabilities of being in a given state, staying in the same state or changing of state, were derived from the behavioural profiles recorded continuously over time for each fish, during 2 h on 2 days. A two-way factorial design with doubly repeated measures was applied to test the effects of stocking density (3 vs. 6 fish·150 l), ration level (1.2 vs. 2.5%), feeding (before vs. after feeding) and time on these time-dependent probabilities. Feeding and time affected significantly the transition probabilities. A state space model was introduced using the estimated time-dependent probabilities to capture the temporal structure of fish behaviour. The generated forecasts corresponded well to observed fish behaviour with R'(2)≥0.50 for four behavioural states.