Changes in blood cortisol, glucose and lactate in carp retained in anglers' keepnets

Capture of carp from holding tanks by dip-net, or from semi-natural conditions by rod and line, elicits a physiological stress response characterised by elevation of plasma cortisol levels. The transfer of carp to keepnets subsequent to capture does not increase or reduce the magnitude or duration of this response and in both cases plasma cortisol levels have returned to pre-stress levels within 24 hours of the initial disturbance. The post-capture plasma cortisol elevation is accompanied by disturbances in plasma glucose and lactate levels but these are less consistent in severity and duration than the cortisol response. These data suggest that the retention of fish in keepnets following capture, does not represent a source of stress additional to that imposed by capture and has no effect on the rate of recovery of the fish from the initial capture stress.