Growth and maturation in Arctic charr (Salvelinus alpinus) in response to different feed rations

Groups of Arctic charr (Salvelinus alpinus) were reared in duplicate tanks supplied with freshwater, and subjected to two different ration levels, 100% (full ration) and 50% (half ration) in two six week periods during autumn (Sept.–Nov.) and winter (Dec.–Feb.). In between the restricted ration periods and from February onwards, all fish were fed full ration. After the first and second 42 day restricted feed periods, the 50% had lower mean weight than the 100% group in both sexes, but this size difference diminished as the trial progressed, and full final size compensation was seen for both males and females in the 50% group. Specific growth rates for both sexes were higher in the 100% group during the two reduced feeding periods, whereas growth was higher in the 50% group in the subsequent periods after feed restriction. No differences in growth were seen from May onwards. Feed conversion efficiency was higher in the 50% group during, and after, feed restriction, and daily feeding rate (F%) was higher in the 50% group in the periods subsequent to feeding restriction. In the following summer and autumn signs of lower maturation were seen for females in the feed restricted group. No differences were found in fillet water- and fat content in the experimental groups. The present findings indicate that intermittent feeding during autumn and winter could be a cost-effective strategy for Arctic charr farmers.