Première évaluation des techniques de marquage d'alevins d'ombre commun (Thymallus thymallus L.) par cautérisation de la nageoire adipeuse ou par injection de micromarques magnétiques

Abstract

It is often necessary to tag fish in order to control the efficiency of stocking or to investigate population dynamics in the wild. The paper deals with adaptations of two methods of tagging young European grayling (Thymallus thymallus L.) of 6-8 cm long: (1) ablation by cauterisation of the adipose fin and (2) injection of coded wire tags into the nasal cartilage. In order to investigate the long-term effects of each tagging techniques, survival and growth of young tagged fish were compared to those of untagged fish. Rearing took place in artificial tanks and ponds. Observed rates of tag retention or tag persistence were very high (> 99%). Both survival and growth rates of tagged and untagged groups of fish, reared apart or not, did not differ significantly. Consequently, both methods appear to be suitable for tagging groups of young grayling.