Body temperature and seawater adaptation in farmed Atlantic salmon and rainbow trout during prolonged chilling |
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Authors: | K-A Rørvik P O Skjervold S O Fjæra T Mørkøre S H Steien |
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Institution: | AKV AFORSK, Institute of Aquaculture Research AS, P.O. Box 5010, N-1432 Ås-NLH, Norway;Department of Agricultural Engineering, Agricultural University of Norway, P.O. Box 5065, N-1432 Ås-NLH, Norway;Hydro Nutrition, Norsk Hydro ASA, Bygdøy alle 2, N-0240 Oslo, Norway |
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Abstract: | The core temperature of the rainbow trout Oncorhynchus mykiss (3·5 kg) dropped to 1·0° C during the first 6 h of chilling at 0·5° C, remained stable until 24 h, and dropped significantly to 0·7° C after 39 h. Blood plasma osmolality increased and muscle moisture content decreased gradually with increasing chilling time. After 39 h of chilling, the rainbow trout experienced 40 mosmol l-1 higher blood plasma osmolality and 2·8% less muscle moisture content compared with initial values. In the Atlantic salmon Salmo salar (5·3 kg), core temperature dropped to 1·3° C and blood plasma osmolality increased significantly during the first 6 h of chilling at 0·5° C, but remained relatively stable throughout the rest of the experimental period. After 39 h of chilling, the salmon experienced 20 mosmol l-1 higher blood plasma osmolality and 0·5% less muscle moisture content compared with initial values. In rainbow trout muscle moisture content was inversely related to blood plasma osmolality indicating reduced seawater adaptation with increasing hours of chilling. No such relationship was observed in the Atlantic salmon. Hence, changes in plasma osmolality and muscle moisture in the Atlantic salmon do not indicate osmoregulatory failure since the new levels, once established, were maintained throughout the chilling time. |
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Keywords: | Atlantic salmon rainbow trout chilling body temperature blood plasma osmolality muscle moisture content |
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