The histopathology of salmon tagging

The process of tagging large numbers of juvenile salmon Salmo salar (L.) to enable studies of their migratory pathways, is now well established. A description of the usual method used in Scotland and the immediate pathological effects of the tagging trauma on the young salmon are contained in a previous paper (Roberts et al. , 1973). The purpose of the present study was to delineate the long term changes which are apparent in the tag wound at the end of the one or two year period which the majority of salmon spend at sea prior to their return to the native river to spawn.