Cohort sampling, anaesthesia and stocking‐density effects on plasma cortisol, thyroid hormone, metabolite and ion levels in rainbow trout, Salmo gairdneri Richardson

Abstract

The effect of serial removal of fish from aquaria, anaesthesia and stocking density on plasma cortisol, thyroid hormone, metabolite and ion levels was examined in rainbow trout, Sulmo gairheri, to determine the consequences of normal handling and maintenance procedures on the activity of the pituitary-adrenal and pituitary-thyroid axes in the species.The capture and handling associated with serial removal of fish from an aquarium resulted in a rapid elevation of plasma cortisol concentrations and a slower rise in plasma glucose, Mg2+ and Na' concentrations; plasma K t levels showed a transient fall shortly after commencing the sampling, followed by a significant increase.A lethal concentration of 3-aminobenzoic acid ethyl ester (MS 222) of 125 mgl-(but not a sublethal concentration of 62.5 ng 1-') prevented the capture stressor-associated changes in most of the measured parameters, including plasma cortisol levels, although plasma protein and ion concentrations were elevated in fish sampled after MS 222-anaesthesia.Stocking densities from 1 to 64 fish 80 I-' aquarium did not appear to effect changes in the measured parameters, except for plasma T 3 n 4 ratios which decreased with increasing stocking density. The exception was found in fish which were stocked in pairs: one member of each pair had a markedly elevated plasma cortisol level and there was a high incidence of mortality, probably related to aggressive social interaction.

Estimation of Carcass Fat and Protein in Northern Pintails (Anas Acuta) During Spring Migration

“…For example, age (Puerta et al, 1990), daily rhythms, starvation, stress, and method of capture can alter blood biochemistry profiles (Harder and Kirkpatrick, 1994). Stress can cause an increase in cholesterol (Franzmann and Thorne, 1970) and protein levels (Laidley and Leatherland, 1988;Marco and Lavin, 1999). Triglyceride levels decline with time between the last triglyceride-rich meal and sampling (Domingo-Roura et al, 2001).…”

Heads or tails? Stressor-specific expression of corticotropin-releasing factor and urotensin I in the preoptic area and caudal neurosecretory system of rainbow trout

“…for up to 2 weeks (Laidley & Leatherland 1988, Winberg & Lepage 1998, Sloman et al 2001. Assessed in pairs, the subordinate fish cannot avoid the dominant fish and is therefore subjected to constant stress.…”

Hormonal modulation of the heat shock response: insights from fish with divergent cortisol stress responses

“…The rationale for this objective originated from a recent study where we determined that dominant and subordinate trout differed in thermal tolerance with subordinate fish exhibiting a lower critical thermal maximum (CT max ) than dominant fish (26). Like LR and HR fish, fish in dominance hierarchies are characterized by distinctive hormone responses to stress; dominant fish typically exhibit lower circulating cortisol levels than subordinate fish (24,34,42). We were thus interested in whether or not the distinct stress hormone profiles in the HR and LR fish were linked to thermal tolerance.…”