Thesis (M.Sc.)--Memorial University of Newfoundland, 2002. / Bibliography: leaves 47-53.

Thèse (M.Ress.Renouv.) -- Université du Québec à Chicoutimi, 2002. / Bibliogr.: f. 89-96. Document électronique également accessible en format PDF. CaQCU

Thèse (M.Ress.Revouv.) -- Université du Québec à Chicoutimi, 2005. / Bibliogr.: f. 38-45. Document électronique également accessible en format PDF. CaQCU

Thesis (M.Sc.)--Memorial University of Newfoundland, 2002. / Includes bibliographical references.

The spatial scale at which populations are genetically structured is of immense interest for the understanding of a species’ ecology and evolutionary biology. This can have important implications for management of resources as well as predicting responses to future change. Rainbow smelt (Osmerus mordax) is an anadromous species with a relatively short freshwater residence time compared to other species with similar life-history strategies. Therefore, while they offer the opportunity to sample distinct spawning aggregations, they also offer an insight into the relative roles of contemporary and historical factors shaping connectivity among marine populations, an area of great interest, and for which further understanding is required. With the use of both mitochondrial DNA and nuclear microsatellite markers, I explored the historical and contemporary factors influencing population structure in smelt. While previous phylogeographic work on this species has resolved two mtDNA lineages dating back to previous glacial episodes, I document the discovery of a zone of contact between these lineages in Newfoundland. This is in addition to the established contact zone in the St. Lawrence estuary, and results in a longitudinal distribution of the races with one race predominating on opposite ends of the species distribution, while the other race is geographically intermediate. Patterns of nuclear genetic variation largely mirror the phylogeographic signals in Newfoundland and suggest a more recent colonization of the Avalon Peninsula as well as implicating a remnant historical signal of colonization of the west coast of Newfoundland from the mainland. In addition, contrasting patterns of genetic diversity and levels of differentiation were apparent between the mainland and Newfoundland and suggest differing scales of dispersal within this species. While the population structure within Newfoundland is most consistent with dispersal restricted to within bays, larger scale biogeographic regions were identified in the mainland range, suggesting dispersal is more common and widespread. In addition, sampling of different run times (i.e. ‘early’ vs. ‘late’) demonstrated the potential for isolation by time when spawning events are separated by a break in activity. Overall, these results shed light into the possible roles of both historical and contemporary factors shaping the dynamics and connectivity among populations.

Thèse (M.Ress.Renouv.) -- Université du Québec à Chicoutimi, 2005. / Bibliogr.: f. 79-85. Document électronique également accessible en format PDF. CaQCU

This thesis explored the influence of fish behavior and distribution on the accuracy and precision of quantitative estimates of fish biomass and abundance as assessed by hydroacoustic techniques. Rainbow smelt (Osmerus mordax), a pelagic fish known to undertake diel vertical migrations and to exhibit changes in aggregation intensity associated with these movements was used as the model species for this study. The diel vertical migrations of smelt resulted in their potential inaccessibility to the acoustic gear. To obviate this problem a model of the diel migration of smelt based on observations of their behavioral responses to ambient light and water temperatures, was developed and used to time acoustic estimates of fish biomass and abundance to periods when they were unbiased by inaccessibility. Acoustic surveys were then conducted to evaluate the direct influence of fish aggregation on estimates of fish abundance, and to examine the effect of changes in fish distributions on the statistical validity of acoustic analyses. Comparative acoustic surveys, conducted when fish were schooled and dispersed, showed abundance was underestimated by up to 50% when schooling prevailed. The influence of changes in the level of fish patchiness, induced by diel schooling, on the statistical precision of acoustic estimates of abundance and biomass was found to be insignificant. Cluster sampling, a robust approach to the inherent problems of transect sampling created by autocorrelated data series was applied to acoustic data for the first time and its effectiveness was assessed. Cluster sampling yielded estimates of biomass and of abundance that were more precise than were estimates based on the traditional approach of analyzing complete transects.

Thèse (M.Ress.Renouv.) -- Université du Québec à Chicoutimi, 2003. / Bibliogr.: f. [70]-76. Document électronique également accessible en format PDF. CaQCU

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