The response to capture and confinement stress of plasma cortisol, plasma sex steroids and vitellogenic oocytes in the marine teleost, red gurnard.

摘要

Adult female red gurnard (Chelidonichthys kuma) were captured and confined in 700 or 2000l tanks for 24, 48, 72 or 96 h (8 fish per treatment). Plasma cortisol levels were significantly lower in the groups confined for 24 and 96 h (34 and 17 ng/ml,respectively) compared to levels at the time of capture (53-125 ng/ml). Plasma oestradiol concentrations decreased from 0.3-0.8 ng/ml at capture to 0.2-0.3 ng/ml after confinement and plasma testosterone from 0.7-1.0 ng/ml to 0.3-0.4 ng/ml. The length ofconfinement had no effect on hormone levels but fish confined for longer lengths of time showed more follicular atresia. In a 2nd experiment fish were blood-sampled every 24 h for 96 h, cortisol levels decreased significantly in the first 24 h but thenshowed no change; oestradiol decreased significantly after 72 h of confinement but testosterone showed no change. It is concluded that if the fish are to be used as broodstock they must be captured outside the period of active vitellogenesis.