Abstract:
This study examined the potentially stressful
effects of tagging juvenile rainbow trout Oncorhynchus mykiss
with passive integrated transponder (PIT) tags by measuring
short-term (<120-h) changes in plasma concentrations of
cortisol and hepatic heat shock protein 70 (hsp70). In a
laboratory experiment, plasma cortisol levels were measured
in fish before they were tagged (0 h) and at 2, 6, 24, and 120 h
after being tagged. Hepatic hsp70 levels were measured at 0,
24, and 120 h. All results were compared with those for fish
that were handled but not tagged. Plasma cortisol levels were
significantly higher in both treatment groups (tagged and
handled but not tagged) at 2 h than in the pretreatment groups
(0 h). Plasma cortisol levels in the treatment groups returned to
near pretreatment levels by 6 h. However, there was a
significant difference in plasma cortisol levels between
treatment groups at 6 h. There were no significant differences
in hepatic hsp70 levels among the two treatment groups, and
hepatic hsp70 levels did not change through time. Our results
suggest that PIT tagging is a low-impact tagging procedure for
juvenile salmonids.
