Floating, switching, or nonswitching as different behaviours when Arctic char (Salvelinus alpinus) are visiting two feeding tanks

The: following questions were addressed. Will individual Arctic char (Salve linus alpinus) differ in their visiting strategies when given a choice betw een two feeding tanks? If so, will the choice of strategy depend on individ ual characteristics (size) and will it affect their success (growth)? Furth er, will their allocation of visits to the two feeding tanks correspond to the food ratio? The passages between the nonfeeding tank and the two equall y rich feeding tanks were recorded for four separate groups during a 3-week period. In an additional study, a single group was continuously monitored for 5 months using the same setup, but the feed ratio between the two feedi ng tanks was changed. Certain individuals in both studies consistently visi ted the same feeding tank (nonswitchers) and these were the most successful ones in terms of growth rate. Other individuals either kept Visiting both tanks (switchers) or spent most of their time in the nonfeeding tank (float ers). These behaviours were applied by individuals that had a lower growth rate and are therefore likely to have lower competitive ability or feeding motivation. No significant difference in initial weight between the behavio ural categories was found in either of the two studies. In the four-group s tudy, the proportion of visits into the two feeding tanks matched the food ratio among the switchers only and the distribution of the groups failed to match the food ratio. In the single-group study, the group distributed acc ording to the food ratio (ideal free distribution) if they were given suffi cient time to learn the quality of the patches. A change in the relative fo od ratio caused the switchers and floaters to alter their visiting behaviou r, always favouring the more profitable tank, whereas the nonswitchers cont inued to visit the same tank.