Cortisol and glucose responses in juvenile brown trout subjected to a fluctuating flow regime in an artificial stream

Abstract

In an artificial stream channel, wild 1 year old brown trout Salmo trutta were exposed to fluctuations in flow and water level to simulate hydro-peaking conditions downstream of a hydropower installation. Blood plasma cortisol concentrations reached a maximum of 59·4 35·3 ng ml 1 (mean 95% CL) 2 h after the end of down-ramping. Return to the pre-exposure cortisol level was achieved within 6 h. When subjected to daily cyclical fluctuations over 7 days, plasma cortisol levels were significantly elevated (61·3 26·8 ng ml 1 ) on the first day compared to undisturbed fish (4·9 3·7 ng ml 1 ). On the fourth and seventh day, no elevation in plasma cortisol above control levels was observed. No changes in blood glucose that could be attributed to the stressor were found. There was no correlation between plasma cortisol and blood glucose levels. The short-lived cortisol response to daily fluctuations indicates a rapid habituation to this stressor. 2002 The Fisheries Society of the British Isles

Stress responses of juvenile brown trout under winter conditions in a laboratory stream

“…The effects of perceived predation risk on different stress responses probably vary among species, and, in particular, effects on cortisol levels may be small in brown trout (Lepage et al, 2001). Nonetheless, individual plasma cortisol concentrations varied greatly, and were all high compared to those in other studies of unstressed or mildly stressed brown trout (Flodmark et al, 2002;Brelin et al, 2005). Mean cortisol concentration was instead roughly the same as those reported for trout after being subjected to handling or confinement stress (Norris et al, 1999;Ruane et al, 1999;Barton, 2000).…”

Energetic Consequences of Stranding of Juvenile Atlantic Salmon (Salmo salar L.)

“…Our experiments did not measure stress, but it has been shown that juvenile brown trout exposed to a fluctuating flow regime quickly recover from this artificial stressor and that their blood cortisol levels normalise already after 6 h after the first low flow stage [22]. When measuring blood cortisol after consecutive days of fluctuating flow and water levels, [22] did not find differences in cortisol levels between the control and treatment fish.…”

“…When measuring blood cortisol after consecutive days of fluctuating flow and water levels, [22] did not find differences in cortisol levels between the control and treatment fish. Although fish showed an initial stress-response to the changes in water flow, the effect was only short lived and brown trout became accustomed to the stressor.…”

“…If they do not suffer from oxygen deficiency, drying-out or capture by predators, they may survive. On the other hand, such experiences may be stressful [22] or cause damage that may affect their longterm performance and survival.…”

Χρήση αναισθητικών ουσιών στο λαβράκι (Dicentrarchus labrax L.) συμβολή τους στον περιορισμό του στρες και επίδρασή τους στο ανοσοποιητικό σύστημα και στην ανάπτυξη

“…Άλλες παράμετροι, οι οποίες είναι ιδιαίτερα σημαντικές σε ορισμένες εκτροφές, όπως οι πεστροφοκαλλιέργειες, είναι η στάθμη και η ροή του νερού εκτροφής, αφού οποιαδήποτε αλλαγή τους μπορεί να αποτελέσει αίτιο πρόκλησης στρες (Flodmark et al 2002).…”