A multivariate comparison of the stress response in three salmonid and three cyprinid fish species: evidence for inter-family differences

The response of six species of freshwater fish, from the families Cyprinidae (common carp Cyprinus carpio; roach Rutilus rutilus; chub Leuciscus cephalus) and Salmonidae (rainbow trout Oncorhynchus mykiss; brown trout Salmo trutta; Arctic charr Salvelinus alpinus), to a standardised stressor was evaluated. A six hour period of confinement resulted in changes to plasma cortisol, glucose, amino acid and lactate levels compared to unconfined controls. There were significant differences in the response profiles both within and between families. The cyprinid species exhibited higher and more sustained stress-induced increases in plasma cortisol and glucose than the salmonid species. In cyprinids plasma lactate and plasma amino acid concentration showed less disturbance following stress than in salmonids. The results of the study, together with an evaluation of previously published data for eight salmonid species and six cyprinid species support the hypothesis that differences in core elements of the stress response exist between species of fish, and that this variation may have a systematic basis.