<p>Aquatic vegetation in the pristine coastal marshes of eastern Georgian Bay (GB) provides critical spawning and foraging habitat for fish species, with complex habitat supporting the greatest diversity. These wetlands are threatened by a changing water level regime and forecasted lower water levels. To monitor and conserve these wetlands, we must understand how they function and respond to this stressor. The overall goals of this thesis are to determine the impact of declining water levels on both wetland fish habitat and the fish community as well as identify the spatial scale of habitat utilization by fishes.</p> <p>We first delineate all coastal wetlands in eastern GB, identifying 3771 wetlands that provide habitat for Great Lakes fishes. Using satellite imagery, we develop an object-based classification method to classify four types of wetland vegetation. Since submerged aquatic vegetation (SAV) is not visible from satellite imagery in GB, we develop a model to predict potential area of this important habitat. The model suggests that the response of SAV to declining water levels depends on wetland geomorphology, but generally, the area of SAV decreases. To assess the response of fish habitat coverage and structure to sustained low-water levels, we classify vegetation in images collected in 2002 and 2008. The result is increasingly homogeneous habitat, a net loss of fish habitat and a decrease in fish species richness. Finally, mark-recapture and radio-tracking are used to evaluate fish movement among closely situated wetlands. Results suggest that the current distance used to group and protect small wetlands provincially (750 m), likely protects most resident fish species, but does not cover movement patterns of a top predator. This research will advance our scientific understanding of freshwater coastal ecosystems and aid in the creation of conservation strategies to mitigate future threats from declining water levels.</p> / Doctor of Philosophy (PhD)

To assess potential impacts of effluents from Key Lake and McClean Lake uranium operations on freshwater systems, morphometric (weight, length, condition factor) and biochemical (total body lipids and triglycerides, liver triglycerides, muscle protein, muscle RNA/DNA ratio) measures of growth and bioenergetics were determined in young-of-the-year (YOY) fishes collected in fall and spring. It was predicted that fishes exposed to mining and milling effluents would be in poorer condition relative to fishes from reference sites and that fishes would be depleted in lipids and triglycerides in the spring compared to the previous fall following a northern winter. Various total body lipid and triglyceride measurement methods were initially compared and validated. <p>Lakes receiving effluent at Key Lake (in operation > 20 years) were higher in metals, ions and ammonia compared to exposure sites at McClean Lake (in operation < 10 years). At Key Lake, there were site and season differences in total body lipids and triglycerides in YOY northern pike (<i>Esox lucius</i>) and burbot (Lota lota), with fishes being fattier at exposure sites compared to fishes at the reference site, and fish being fattier in spring relative to fall. A local prey item, spottail shiners (<i>Notropis hudsonius</i>), from an exposure lake were higher in triglycerides compared to shiners from a reference site, suggesting an indirect effect of uranium operation effluent on pike and burbot bioenergetics via food web enrichment. At McClean Lake, there were site and season increases in lipids and triglycerides in burbot from the exposure site, however there were no site differences in any morphometric or biochemical endpoint for northern pike. Slimy sculpin (<i>Cottus cognatus</i>) were the only species with lower triglyceride content in the spring following winter. <p>Overall, biochemical measures of growth (muscle protein, muscle RNA/DNA ratio) did not vary with effluent exposure at either uranium operation. Lipids and triglycerides were useful biochemical endpoints that frequently detected site and season differences in fish condition that were not noted with morphometric measures. Site and season differences in fish lipids and triglycerides at sites receiving mining and milling effluents revealed an impact of the uranium operations on indigenous YOY fish condition.

To assess potential impacts of effluents from Key Lake and McClean Lake uranium operations on freshwater systems, morphometric (weight, length, condition factor) and biochemical (total body lipids and triglycerides, liver triglycerides, muscle protein, muscle RNA/DNA ratio) measures of growth and bioenergetics were determined in young-of-the-year (YOY) fishes collected in fall and spring. It was predicted that fishes exposed to mining and milling effluents would be in poorer condition relative to fishes from reference sites and that fishes would be depleted in lipids and triglycerides in the spring compared to the previous fall following a northern winter. Various total body lipid and triglyceride measurement methods were initially compared and validated. <p>Lakes receiving effluent at Key Lake (in operation > 20 years) were higher in metals, ions and ammonia compared to exposure sites at McClean Lake (in operation < 10 years). At Key Lake, there were site and season differences in total body lipids and triglycerides in YOY northern pike (<i>Esox lucius</i>) and burbot (Lota lota), with fishes being fattier at exposure sites compared to fishes at the reference site, and fish being fattier in spring relative to fall. A local prey item, spottail shiners (<i>Notropis hudsonius</i>), from an exposure lake were higher in triglycerides compared to shiners from a reference site, suggesting an indirect effect of uranium operation effluent on pike and burbot bioenergetics via food web enrichment. At McClean Lake, there were site and season increases in lipids and triglycerides in burbot from the exposure site, however there were no site differences in any morphometric or biochemical endpoint for northern pike. Slimy sculpin (<i>Cottus cognatus</i>) were the only species with lower triglyceride content in the spring following winter. <p>Overall, biochemical measures of growth (muscle protein, muscle RNA/DNA ratio) did not vary with effluent exposure at either uranium operation. Lipids and triglycerides were useful biochemical endpoints that frequently detected site and season differences in fish condition that were not noted with morphometric measures. Site and season differences in fish lipids and triglycerides at sites receiving mining and milling effluents revealed an impact of the uranium operations on indigenous YOY fish condition.

No description available.

Genetic variation is essential for biological evolution, for maintaining viability of populations, and to ensure ecosystem resilience. Increased human exploitation and environmental change result in rapid loss of biological variation, including genetic diversity. Measures to halt this trend require that biological diversity is assessed and monitored. Assessment of biodiversity includes identifying patterns of distribution of genetic variation within individual species. This thesis focuses on spatial genetic structure and assessment of units for conservation in continuous environments without apparent migration barriers. Empirical data refer to Scandinavia and the model species are northern pike (Esox lucius), brown trout (Salmo trutta), and harbour porpoise (Phocoena phocoena). Questions regarding monitoring genetic diversity and releases of alien populations are also addressed.  The spatial genetic structure of the northern pike in the Baltic Sea is characterized by isolation by distance and continuous genetic change. Positive genetic correlation was found among pike within geographical distances of less than 150 km. This distance may be used to suggest management units in this area. For the brown trout, genetic monitoring identified two sympatric populations within a small mountain lake system. The situation is characterized by a clear genetic but no apparent phenotypic dichotomy. Scientific support for a genetically distinct Baltic harbour porpoise population is limited, and the spatial genetic structure of the harbour porpoise in Swedish waters needs to be clarified. Data for launching conservation genetic monitoring programs is available for only a few Swedish species. Millions of forest trees, fish, and birds are released annually in Sweden and the documentation on these releases is poor. To meet responsibilities of safeguarding biodiversity and surveying biological effects of releases, there is an urgent need for studies aimed at evaluating genetic diversity. / At the time of the doctoral defense, the following paper was unpublished and had a status as follows: Paper 2: Manuscript.

Les téléostes, le clade possédant le plus d’espèces parmi les vertébrés, emploient une saisissante diversité de mécanismes de détermination du sexe, incluant des mécanismes génétiques et environnementaux. Des études récentes ont identifié de nombreux nouveaux régulateurs génétiquesdu développement sexual des poissons et ont introduit la notion de “terrain de jeux évolutif”. Le but de ce projet de thèse est de donner une vue complète des dynamiques évolutives des déterminants du sexe dans un ordre de téléostes, les Esociformes. Dans notre espèce focale, Esox lucius, nous avons identifié une duplication d’un membre de la famille des TgfB – une famille qui a émergé en tant que fondamentale dans la régulation du sexe chez les téléostes – comme MSD (gène controlant la détermination du sexe). Nous avons obtenu des preuves fonctionnelles du rôle de ce gène en tant que MSD, de son interaction avec des facteurs environnementaux, ainsi que des nouvelles informations sur les processus évolutifsCe gène est perdu dans une population de la même espèce en Amérique du Nord, mais il est conservé parmi les autres Esociformes. En parallèle, d’autres systèmes de détermination du sexe ont été identifiés dans des espèces proches. De plus, dans des clades plus distants comme Umbra et Dallia, le MSD d’Esox n’est pas présent, et d’autres mécanismes implicants de nouveaux MSD ont été identifiés, complefixiant l’histoire évolutive des MSD dans ce groupe, qui reflète la plasticité génétique observée dans les téléostes en général. / Teleost fishes, the most species-rich clade among vertebrates, employs an astonishing diversity of sex-determining (SD) mechanisms, including environmental and genetic systems. Recent studies identified many new genetic regulators in fish sexual development that lead to the notion of an 'evolutionary playground'.This thesis project aims to provide a complete picture of the evolutionary dynamic of SD systems within a small order of teleost, Esociformes. In our focal species Esox lucius, we idenWhile the gene is lost in another population of the same species rapidly possibly during post-glacial recolonization process, it is well conserved among different species. Meanwhile, additional transition of SD system have also been identified in a sister Esox species. Moreover, in the most distant genera Dallia and Umbra, the Esox master SD gene is not present and we found different SD mechanisms with novel SD genes that adds additional layers of complexity to this group, which mirrors the observed high genetic plasticity in teleost SD

Top predators in aquatic ecosystems often have strong top-down effects on the ecosystem. Northern pike (Esox lucius) has been documented to cause whitefish (Coregonus lavaretus) populations to diverge into different ecomorphs. This can facilitate piscivory in other predators as a novel resource becomes available to them in the form of dwarf whitefish. The aim of this study is to examine whether the presence of pike causes Eurasian perch (Perca fluviatilis) to shift their diet from insectivory to piscivory, and whether this is directly driven by whitefish polymorphism. Stomach contents of 147 perch from lakes with and without pikes were analyzed. The results show that the presence of pike has a clear influence on the diet of the perch. In lakes without pike, perch are mostly insectivorous, and in lakes with pike, they are mostly piscivorous. This diet shift appears to be driven by whitefish availability, as a majority of the diet of perch in pike lakes consisted of whitefish, while none of the fish eaten by perch in non-pike lakes was whitefish. In addition, the results showed that perch undergo the diet shift from insectivory to piscivory at a smaller size when coexisting with pike. This study can be added to the growing body of evidence for the ecological significance of pike.

No description available.

The population of northern pike in the Baltic sea has seen a drasticdecrease in numbers in the last couple of decades. The reasons for this are believed to be many, but the majority of them are most likely anthropogenic. Today, many measures are being taken to prevent further decline of pike populations, ranging from nutrient runoff control to habitat restoration. This inevitably gives rise to the problem addressed in this project, namely: how can we best monitor pike populations so that it is possible to accurately assess and verify the effects of these measures over the coming decades? Pike is currently monitored in Sweden by employing expensive and ineffective manual methods of individual marking of pike by a handful of experts. This project provides evidence that such methods could be replaced by a Convolutional Neural Network (CNN), an automatic artificial intelligence system, which can be taught how to identify pike individuals based on their unique patterns. A neural net simulates the functions of neurons in the human brain, which allows it to perform a range of tasks, while a CNN is a neural net specialized for this type of visual recognition task. The results show that the CNN trained in this project can identify pike individuals in the provided data set with upwards of 90% accuracy, with much potential for improvement.

The aim of this diploma thesis is to compare quality of northern pike sperm collected by different methods. First method is collection of stripped sperm by abdominal massage of the belly. Second method is collection of stripped sperm with special catheter to eliminate sperm contamination by urine. The last method is collection of testicular sperm. Differently collected sperm was evaluated and compared its quality. The main observed parameters were sperm volume, spermatozoa concentration, spermatozoa motility and velocity and osmolality of seminal fluid. Sperm samples were used for eggs fertilization. In fertilized eggs, the fertility of eggs and larvae hatching rate were observed.