Maternal effects of migration on sympatric offspring of resident and anadromous Atlantic salmon (Salmo salar)

Simms, Michelle (2014) Maternal effects of migration on sympatric offspring of resident and anadromous Atlantic salmon (Salmo salar). Masters thesis, Memorial University of Newfoundland.

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Abstract

Many of the coastal rivers in Newfoundland contain Atlantic salmon populations which include both anadromous (i.e. migrate to sea) and non-anadromous (i.e. freshwater resident) phenotypes. However, little is known about the relationship between the two types and particularly, how early offspring performance (i.e. growth, dominance and survival) may differ as a result of maternal effects (e.g., marine versus freshwater derived nutrients in the eggs). Six pairs of paternal half sib families were created by crossing unique anadromous and resident mothers with a single male (anadromous or resident). Samples were collected at each of four stages (i.e. unfertilized eggs, eyed eggs, yolk-sac larvae and newly emerged fish), weighed and used for lipid analyses. All samples were processed and lipid profiles were determined by Iatroscan instrumentation and further characterized and quantified by gas chromatography. There were no significant differences in triacylglycerols (TAG) or phospholipids (PL) between the two offspring types, however the anadromous offspring had higher amounts of eicosapentaenoic acid (EPA, 20:5ω3), docosahexaenoic acid (DHA, 22:6ω3) and ω3:ω6 fatty acids. The resident offspring had higher amounts of arachidonic acid (AA, 20:4ω6). Results also showed that resident mothers had larger eggs and their offspring were larger at emergence. Pair-wise dominance trials between newly emerged anadromous and resident offspring revealed no significant difference in positioning relative to a defensible food source. Similarly, growth and survival of the newly emerged offspring, tested over a four week period in stream channels and across three treatments (12 resident offspring, 12 anadromous offspring, and 6 offspring of each type; five replicates of each), differed little. Thus, while there were apparent differences in maternal contributions to the offspring, there were no indications under the experimental conditions examined that these strongly influenced offspring performance after emergence.

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