Physiology during smoltification in Atlantic salmon: effect of melatonin implants

• Melatonin implants were used to override natural melatonin rhythm in groups of juvenile Atlantic salmon, Salmo salar, raised at simulated natural photoperiod (SNP) and constant light (LL) from mid-March until end of August. The experiment contained also both sham control (with non-melatonin implants) and control (no implants). No differences were found in the experimental variables between these two control groups. Growth and food intake were negatively affected by melatonin implantation. Overall, higher GH levels were observed in the SNP melatonin-implanted group, whereas no differences in GH levels were seen between the SNP control, LL control, or the LL melatonin-implanted groups. Highest food intake was seen in the LL control group. No differences in food intake were recorded between the LL melatonin-implanted and SNP control groups. Gill Na+, K+, ATPase (NKA) activity was influenced by time as well as the interaction between photoperiod and time. No differences in gill NKA activity or plasma chloride levels following transfer to seawater were seen between the groups with melatonin implants and their controls. Based on the present results, it seems apparent that melatonin does play a role in regulating food intake and growth in Atlantic salmon smolts.

Ämnesord

NATURVETENSKAP  -- Biologi (hsv//swe)

NATURAL SCIENCES  -- Biological Sciences (hsv//eng)

Nyckelord

Melatonin implant

Growth

Food intake

Growth hormone

Atlantic salmon

TURBOT SCOPHTHALMUS-MAXIMUS

PARR-SMOLT TRANSFORMATION

FACTOR-I

CONCENTRATIONS

GROWTH-HORMONE LEVELS

RAINBOW-TROUT

ONCORHYNCHUS-MYKISS

PLASMA MELATONIN

SALAR L

PHOTOPERIOD

MATURATION

LBOT C

1983

JOURNAL OF FISH BIOLOGY

V23

P211

CORMICK SD

1993

CANADIAN JOURNAL OF FISHERIES AND AQUATIC SCIENCES

V50

P656

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