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Lookup NU author(s): Professor Selina Stead
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This paper discusses current issues and future prospects of salmon farming in Scotland with an emphasis on how knowledge on feeding behaviour (food consumption) can help to reduce environmental impacts of fish farming in coastal zones. The effects of day length (photoperiod), sea water transfer, ration level and sexual maturation on food consumption measured using X-radiography - were examined in individual Atlantic salmon, Salmo salar L. in 3 experiments. In experiment 1, fish reared under a long day (LD) light regime (LD 16 hours light: 8 hours darkness) in autumn had higher feeding rates compared with fish on a shorter day (SD) light regime (SD 8:16; P<0.05). In the second experiment, individual food consumption rates increased with increasing ration level (0.5, 1.0 and 3.0% body weight day(-1)) in fresh water and sea water except immediately after transfer to sea water (P<0.05). Levels of steroid hormones were measured by radioimmunoassay to detect sexual maturation in males and females in sea water in experiment 3. Two phases of development associated with sexual maturation were identified; an early phase (October-April) characterised by slowly rising steroid hormone levels concomitant with high rates of feeding and a late phase (May-October), in which steroid hormone levels increased more rapidly and food consumption rates decreased. These findings are applied to salmon farming, particularly in coastal zones, to show how information on changes in food consumption of fish as they grow in fresh water and then in sea water can be helpful in developing an integrated approach to management so that environmental impacts are minimised.
Author(s): Stead SM
Publication type: Article
Publication status: Published
Journal: Periodicum Biologorum
ISSN (print): 0031-5362
Publisher: Hrvatsko Prirodoslovno Drustvo