Memorial University DAI: Evidence for genetically distinct sympatric populations of anadromous and nonanadromous Atlantic salmon, Salmo salvar

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Title	Evidence for genetically distinct sympatric populations of anadromous and nonanadromous Atlantic salmon, Salmo salvar
Author	Birt, Timothy Peter, 1957-
Description	Thesis (Ph.D.)--Memorial University of Newfoundland, 1990. Biology
Date	1990
Pagination	xi, 139 leaves : ill., maps
Subject	Atlantic salmon--Newfoundland and Labrador--Genetics; Ouananiche
Degree	Ph.D.
Degree Grantor	Memorial University of Newfoundland. Dept. of Biology
Discipline	Biology
Language	eng
Spatial Coverage	Canada--Newfoundland and Labrador
Notes	Bibliography: leaves 126-139
Abstract	This study investigated the genetic relationship between syropatric anadromous and nonanadromous Atlantic salmon in the Gambo River system, eastern Newfoundland. Both forms were cultured in the laboratory and seasonal patterns of development were monitored and compared. Growth rates were not different during most of the first year of life, however smolting anadromous salmon (1+) grew more rapidly than nonanadromous salmon for several weeks prior to the time of seaward migration. Several other physiological parameters associated with the parr-sraolt transformation were measured; no difference was noted in seasonal profiles of total body moisture, condition factor or plasma Na+ and C1- concentrations. Both groups exhibited increasing levels of integumentary silvering during the late winter and early spring although this pattern was more marked among the anadromous group. Gill Ha+-K- ATPase activity increased over the same period in both groups, however mean activities among the nonanadromous salmon were consistently lower, similarly, anadromous salmon displayed more, and larger chloride cells in the gill epithelium as revealed by light microscopy. Salinity tolerance was well developed in both forms in April and June despite differences in chloride cell abundance and Na+-K- ATPase activity. Sexual maturation did not occur among female postsmolts of either group nor among male anadromous postsmolts when cultured in freshwater and seawater. Most male nonanadromous salmon did mature as 'postsmolts'.--Mitochondrial DNA variation was also examined among wild salmon of both forms using restriction enzymes. The Atlantic salmon mitochondrial genome contains approximately 16, 700 bp. No evidence was found for either length polymorphism or sequence heteroplasmy. Variable restriction fragment patterns were generated by five of eighteen enzymes; all variants could be accounted for by single base pair substitutions. Four distinct mitochondrial DNA genotypes were found. Pairwise sequence divergence estimates among genotypes range from 0.2 - 1.0 percent. Significant genotype frequency differences were observed among the two forms. -- Results of this study are consistent with the hypothesis that anadromous and nonanadromous salmon in the Gambo River system represent genetically distinct reproductive units. Reproductive isolation is supported by the observation that the two forms use different spawning sites and that spawning times differ to some extent. Until further research is done to verify these observations it would be prudent to manage the two forms in this system (and possibly others as well) as separate stocks.
Type	Text
Resource Type	Electronic thesis or dissertation
Format	Image/jpeg; Application/pdf
Source	Paper copy kept in the Centre for Newfoundland Studies, Memorial University Libraries
Local Identifier	76072897
Rights	The author retains copyright ownership and moral rights in this thesis. Neither the thesis nor substantial extracts from it may be printed or otherwise reproduced without the author's permission.
Collection	Electronic Theses and Dissertations
Scanning Status	Completed
PDF File	(37.66 MB) -- http://collections.mun.ca/PDFs/theses/Birt_TimothyPeter2.pdf
CONTENTdm file name	20885.cpd