Date of Award

10-12-2011

Degree Type

Thesis

Degree Name

Master of Science (MS)

Department

Environmental Science and Biology

Abstract

Highly unsaturated fatty acids (HUFA) are important nutrients for fish survival, development, and reproduction. Fish oil (PO), rich in HUFA, is the dominant lipid source for first feeds in salmonid aquaculture. To determine if other lipid sources would influence survival, growth, and fatty acid profiles in lake trout (Salvelinus narnaycush) alevins, two 8-week feeding experiments were performed. Diets used in the Artemia Experiment included: diet 1, non-enriched Artemia; diet 2,SELCO-enriched Artemia; diet 3, Super SELCO-enriched Artemia; and diet 4, Bio Vita #0, all of which had significantly different fatty acid compositions. The Fish Oil Replacement Experiment used diets that differed solely in lipid source and fatty acid composition: diet 1, oleic acid (OA); diet 2, linseed oil (LO); diet 3, cod liver oil (CLO); and diet 4, lecithin (LE).

Results from both experiments show that dietary lipid source and fatty acid composition can significantly influence survival, growth, and fatty acid composition of lake trout alevins. In the Artemia Experilnent, lake trout fed a non-enriched Artemia diet lacking in HUFA displayed lower growth than fish fed enriched Artemia diets that included HUFA although survival was not significantly different among treatments. Lake trout fed Super SELCO-enriched Artemia, which had the highest concentration of HUFA, did not differ statistically to lake trout fed SELCO-enriched Artemia for any growth parameter. In the Fish Oil Replacement Experiment, lake trout fed the OA diet, which was lacking in essential fatty acids (linolenic acid (18:3n-3) and linoleic acid (18:2n-6)) and HUFA, had significantly lower survival and growth. Fish fed CLO had significantly higher final length and mass but were statistically similar to fish fed the LE diet in regards to mass gain, SGR, FCR, and K. In both experiments, neutral and phospho-lipid fatty acid profiles of whole body lake trout were reflective of dietary fatty acids. These experiments suggest lipid source and dietary fatty acids can greatly affect the survival, growth, and fatty acid composition of lake trout alevins but alternatives to fish oil, such as vegetable oils, may be a suitable substitute in the first feed of lake trout.

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