Time Learning and Anticipatory Activity in Groups of Arctic Charr

Time learning and anticipatory activity were studied in five groups of 16-17 Arctic charr (Salvelinus alpinus) using self-feeding devices with individual recognition (PIT (Passive Integrated Transponders)-tags). The fish were kept under a LD 12:12 h cycle and periods of free access to the food were alternated with periods of time-limited (2 h) access to food. Self-feeding activity was significantly related to the light period in unrestricted conditions while related to the feeding periods during time-limited access to food. The fish learned to concentrate their feeding activity to the restricted mealtime (> 50% of the daily self-feeding activity) within 10 d. The food anticipatory activity, measured as an increased self-feeding activity before the feeding time and as aggressive interactions close to the trigger, was significant in both cases. The dominant individuals increased the trigger activity in advance of the time-restricted reward period and subdominant individuals approached the trigger also in advance, inducing aggressive interactions. Thus, anticipating and learning a temporally predictable food source was pronounced in groups of self-feeding Arctic charr.