Seasonally changing metabolism in Atlantic salmon (Salmo salar L.) I – Growth and feed conversion ratio |
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| Authors: | U Nordgarden F Oppedal GL Taranger G-I Hemre & T Hansen |
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| Institution: | Department of Aquaculture, Institute of Marine Research, Matre Aquaculture Research Station, Matredal, Norway;;National Institute of Nutrition and Seafood Research, Bergen, Norway |
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| Abstract: | To determine seasonal variation in growth and feed conversion ratio (FCR), Atlantic salmon postsmolts (Salmo salar L.) were exposed to either simulated natural photoperiod (SNP) for 12 months or continuous light (LL) from January to June followed by SNP until December. Feed was given to excess and uneaten feed pellets were collected after every meal for estimation of feed intake and calculation of FCR. Body weight increased from 1086 ± 9 g (mean ± SEM) in January to 4970 ± 7 g (SNP) and 5190 ± 23 g (LL) in December. Specific growth rate (SGR), condition factor and feed intake displayed strong seasonal variation in both groups. Measurements of the thermal growth coefficient correlated highly with SGR (r = 0.98, P < 0.05), indicating that the seasonal variation in SGR was independent of temperature and fish size. Continuous light treatment resulted in increased growth from spring, while the fish exposed to simulated natural light had increased growth rate in late summer. Furthermore, LL improved FCR. Periods of high SGR were concurrent with periods of low FCR in both groups. |
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| Keywords: | feed conversion ratio growth Salmo salar season |
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