Effects of feed quality and quantity on growth, early maturation and smolt development in hatchery-reared landlocked Atlantic salmon Salmo salar

• The effects of feed quality and quantity on growth, early male parr maturation and development of smolt characteristics were studied in hatchery reared landlocked Atlantic salmon Salmo salar. A 2x2 factorial design was used, with two levels of feed rations and lipid content of the feed. The fish were reared from first feeding until release in May the second year. At the end of the experiment salmon fed high rations, regardless of lipid content, grew the most, whereas salmon fed low lipid feed with low rations grew the least. In addition, fish fed low lipid feed had lower body lipid levels than fish fed high lipid feed. Fish from all treatments showed some reduction in condition factor (CF) and lipid levels during their second spring. Smolt status was evaluated using both physiological and morphological variables. These results, based on Na+, K+-ATPase (NKA) enzyme activity, saltwater tolerance challenges and visual assessments, were consistent with each other, showing that salmon from all treatments except the treatment in which fish were fed low rations with low lipid content, exhibited characteristics associated with smolting at two-years of age. Smolting was mainly affected by feed rations; fish fed higher rations experienced enhanced smolting. Sexually mature male parr from the high ration, high lipid content treatment were also subjected to saltwater challenge tests, and were found to be unable to regulate plasma sodium levels. Low feed rations noticeably reduced the proportion of sexually mature male parr, while there was no difference related to lipid content of feed. Fish fed low rations with low lipid content exhibited the highest degree of severe fin erosion.

Ämnesord

NATURVETENSKAP  -- Biologi -- Ekologi (hsv//swe)

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

NATURVETENSKAP  -- Biologi -- Zoologi (hsv//swe)

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

Nyckelord

lipid content; Na

K+-ATPase; osmoregulation; smolt status; smolting

Biology

Biologi

Biology with specialization in Comparative Physiology

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