Incorporating molecular genetic data into management decisions would provide fisheries managers with new tools to identify the magnitude of population structure, metapopulation dynamics, at risk populations, and possible genetic interactions between species, so that management strategies could be tailored to better support long-term viability of species and populations. Alewife (Alosa pseudoharengus) and Blueback Herring (Alosa aestivalis) are two closely related anadromous clupeid fishes native to the Atlantic coast of North America. Current management strategies for these two species, collectively known as river herring, take no account of stock structure or even the distinction between the two species. Using 12 neutral microsatellite loci, I examined at multiple spatial scales the patterns of population structure and genetic differentiation for river herring, with particular reference to comparisons of population structure in the U.S., where extensive stocking has occurred, and Canada, where there has been no stocking. Results suggested strong population structure within the Canadian portion of the range and weaker population structure in the U.S. portion. Highly significant genetic isolation by distance (IBD) for parts of the range unaffected by stocking provided evidence of natal homing and limited dispersal. The differing IBD results obtained in three Canadian regions may reflect differences in historical biogeographical factors and contemporary dispersal patterns among regions. Very weak differentiation and an absence of significant IBD for American stocked populations provided evidence that stocking has reduced genetic differentiation between populations in the U.S. portion of the range, except for two divergent stocked populations that appeared to have resisted homogenization. Evidence of recent population bottlenecks were identified in both U.S. and Canadian populations. The genetic structure of Blueback Herring populations appeared to be similar to that seen in Alewife. When sampled in the same river, Alewife and Blueback Herring were strongly differentiated, although hybrids of the two species were detected. Evidence of genetic impacts of stocking, regional variation in patterns of population structure and complex genetic interactions between the species suggest that current management strategies should be re-evaluated.
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:NSHD.ca#10222/21664 |
| Date | 21 March 2013 |
| Creators | McBride, Meghan |
| Source Sets | Library and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada |
| Language | English |
| Detected Language | English |
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