Previous studies on fishes exposed to effluent from the Key Lake uranium mill in northern Saskatchewan have demonstrated elevated lipids in young-of-the-year pike (Esox lucius), deformities in larval pike and decreased survival of fathead minnows (Pimephales promelas). The objectives of this thesis were to evaluate possible factors that could be contributing to altered bioenergetics of juvenile northern pike inhabiting lakes receiving effluent from the Key Lake operation and to examine the effects of effluent exposure on biomarkers of oxidative stress and histopathology of target organs. Although glycogen and triglycerides stores were significantly greater in pike from exposure lakes compared to the reference, triglycerides stores of juvenile pike prey items showed no overall differences among lakes. Measures of parasitism, however, were negatively correlated with pike bioenergetics thereby reflecting a possible energetic cost of parasitism on reference lake fish. The degree of infection by intestinal parasites and gill monogeneans was greatest in reference pike and intermediate in low exposure pike, whereas high exposure pike harboured no parasites. <p>Arsenic, nickel and selenium are elevated in lakes downstream of the Key Lake mill and have been shown to be associated with increased reactive oxygen species (ROS) in biological systems causing oxidative stress. The potential for oxidative stress was assessed in pike liver and kidney using several biomarkers. Overall, the concentrations of total, reduced and oxidized glutathione and the ratio of oxidized to reduced glutathione did not differ significantly among exposure and reference pike. The activity of glutathione peroxidase was greater in high exposure than reference liver whereas, contrary to predictions, lipid peroxidation was greater in reference than exposure pike tissues. <p>Histopathological evaluations revealed greater kidney and gill pathology in reference lake pike, whereas for liver, hepatocyte morphology differed among lakes without any clear signs of pathology. Trace metal analyses of muscle showed that eight elements (arsenic, cobalt, copper, iron, molybdenum, selenium, thallium, uranium) were significantly elevated in exposure pike. These results provide only limited evidence of oxidative stress in exposure pike tissues and no evidence of histopathology despite indications that metals are bioaccumulating in tissue. Overall, the results from this thesis suggest that the health and condition of juvenile northern pike living downstream of the Key Lake uranium mill may not be compromised by effluent exposure.

Previous studies on fishes exposed to effluent from the Key Lake uranium mill in northern Saskatchewan have demonstrated elevated lipids in young-of-the-year pike (Esox lucius), deformities in larval pike and decreased survival of fathead minnows (Pimephales promelas). The objectives of this thesis were to evaluate possible factors that could be contributing to altered bioenergetics of juvenile northern pike inhabiting lakes receiving effluent from the Key Lake operation and to examine the effects of effluent exposure on biomarkers of oxidative stress and histopathology of target organs. Although glycogen and triglycerides stores were significantly greater in pike from exposure lakes compared to the reference, triglycerides stores of juvenile pike prey items showed no overall differences among lakes. Measures of parasitism, however, were negatively correlated with pike bioenergetics thereby reflecting a possible energetic cost of parasitism on reference lake fish. The degree of infection by intestinal parasites and gill monogeneans was greatest in reference pike and intermediate in low exposure pike, whereas high exposure pike harboured no parasites. <p>Arsenic, nickel and selenium are elevated in lakes downstream of the Key Lake mill and have been shown to be associated with increased reactive oxygen species (ROS) in biological systems causing oxidative stress. The potential for oxidative stress was assessed in pike liver and kidney using several biomarkers. Overall, the concentrations of total, reduced and oxidized glutathione and the ratio of oxidized to reduced glutathione did not differ significantly among exposure and reference pike. The activity of glutathione peroxidase was greater in high exposure than reference liver whereas, contrary to predictions, lipid peroxidation was greater in reference than exposure pike tissues. <p>Histopathological evaluations revealed greater kidney and gill pathology in reference lake pike, whereas for liver, hepatocyte morphology differed among lakes without any clear signs of pathology. Trace metal analyses of muscle showed that eight elements (arsenic, cobalt, copper, iron, molybdenum, selenium, thallium, uranium) were significantly elevated in exposure pike. These results provide only limited evidence of oxidative stress in exposure pike tissues and no evidence of histopathology despite indications that metals are bioaccumulating in tissue. Overall, the results from this thesis suggest that the health and condition of juvenile northern pike living downstream of the Key Lake uranium mill may not be compromised by effluent exposure.

The Rideau River Waterway, also known as the Rideau Canal, is a constructed navigation channel that links Ottawa to Kingston, Ontario. Opened in 1832, it was designated a Canadian Heritage Site in 2003 and a UNESCO World Heritage Site in 2007. South of Smiths Falls, the Rideau Canal consists of a series of 14 interconnected lakes, primarily used for recreational purposes, as well as commercial fishing. The objectives of this study were to examine the spatial and temporal distributions of anthropogenic elements to three headwater lakes of the Rideau Canal system and to examine the relationship between sport fish Hg and historical sediment Hg concentrations. Utilizing paleolimnological techniques, historical records of As, Cd, Co, Cr, Cu, Hg, K, Ni, Pb, Rb, and Zns were analyzed from chronologically deposited lake sediments. Overall, Indian Lake, though the smallest of the three studied lakes, consistently had the highest overall As, Cd, Cu, Hg, Ni, Pb and Zn concentrations. While all peak concentrations were buried, recent surface sediment Hg, Cd, and Zn concentrations still remain above the federal interim sediment quality guideline and the concentration of Pb remains above the federal probable effect level within Indian Lake, leading to continued concern for human and ecosystem health. The general agreement between lake sediment profiles for Cd, Pb and Zn and then Cu and Ni suggest that each group of elements is primarily contributed from the same source. The similarity in trends and timing of peak concentrations between the study lakes and other Ontario lakes suggests large-scale, atmospheric contributions of elements to the freshwater systems in the area. Although only historical northern pike (Esox lucius) THg tissue concentration data was available for analysis, results indicate that concentrations in fish have decreased more than 60% since the late 1970’s, while sediment THg concentrations have decreased 35% within the same time period. Overall, this study has demonstrated that the headwater lakes to the Rideau Canal are presently impacted by elements, at concentrations which are of potential concern for human health. / Thesis (Master, Biology) -- Queen's University, 2009-09-26 00:02:42.317

As two species diverge, much of their genomes begin to differentiate. In many lineages, however, the genomic structure remains remarkably intact, with orthologous gene content maintained across millions of years and significant changes to their biological characteristics. The maintenance of gene content is defined as conserved synteny while the preservation of gene order is defined as conserved linkage; the conservation of both can be incredibly informative when interrogating and comparing two genomes. In non-model organisms, linkage conservation to a well-developed model allows informed, cost-effective and rapid answers to fundamental biological questions without generation of equivalent resources. With the development of new model organisms, we can begin to discuss more fundamental evolutionary concepts, such as the maintenance of chromosomal gene content across larger evolutionary time-scales, or the reorganization that occurs in chromosomes following major genomic events such as whole-genome duplications. In this work, I utilized the rapid development of primary genomic resources in the non-model teleost sablefish (Anoplopoma fimbria) to demonstrate that conserved linkage to a model genomic reference can identify the gene most likely responsible for genetic sex-control. I then assembled the first genome for a non-duplicated member of the teleost lineage Protacanthopterygii, the northern pike (Esox lucius), and demonstrated the conservation of synteny between three major lineages of teleosts, the Protacanthopterygii, the Acanthopterygii and the Ostariophysi. I further showed that the genome of northern pike retains an ancestral teleost organization and pre-duplicated genome in comparison to the economically important Salmoniformes. Finally, with continued improvements of the genome to the chromosome level, I demonstrated the degree of conserved linkage maintained between Atlantic salmon and northern pike and explained how conserved linkage through both genomes could be used to improve the genome assembly of the other, even with over 125 million years of separation. As genomic technology continues to advance and new genomic resources become available, the continued refinement of genome re-organization post duplication will be revealed, and this pre-duplication outgroup will continue to push our understanding of the effects of genome duplication, as we transition from genome organization to functional modifications of gene duplicates following duplication. / Graduate / 2018-12-01

The Northern Pike have recorded the highest accelerations for marine propulsors. The mean peak acceleration and velocity for a number of trials were found to be 120 ms-2 and 4 ms-1 respectively (Harper and Blake 1990) for live fish. Here, we emulate this fast-start motion and analyze the performance of the Northern Pike, using a mechanical fish. The mechanical fish was made of a PVC head attached to a spring steel frame with aluminum ribs and a plastic tail. A latex rubber sheet was used as the skin of the fish. The set-up used air bearings for frictionless motion with two degrees of freedom. The fish was bent to a C shape using servo motors. The two stages of the fast-start motion of a live fish with preparatory and propulsive strokes were closely replicated with this experimental set-up. The results showed that the acceleration profiles were qualitatively similar to that of the live fish. The objective of this project was to understand the mechanism by which the high acceleration is achieved in live fish. The designed mechanical fish was used to quantify the influence of the timing of each stroke and the shape and stiffness of the tail on the observed peak acceleration.

Northern Pike (Esox lucius) is an economically and ecologically valuable species with a circumpolar distribution across the Northern Hemisphere. Northern Pike have been shown to have low levels of genetic variation despite their great capacity to colonize new environments. Here, high-resolution resequencing data from 47 Northern Pike from across North America was used for SNP discovery and population analysis. Our analysis reveals an extraordinary lack of genetic variation among Northern Pike with observed heterozygosity (Ho) of just 0.0835. Our analyses suggest that two major groups of Northern Pike exist in North America that are separated by the North American Continental Divide. Genetic variation associated with the stratification of these two groups resides across the genome particularly in gene regions with multiple copy number variants and functions related to immunity, tissue permeability, and development. Northern Pike from Alaska and the Yukon River harbour about two times more heterozygosity than Northern Pike east of the Continental Divide with an average of one heterozygous SNP every 6,250 bases. Populations east of the Continental Divide possess a remarkable level of genetic homogenization with an average of just one heterozygous SNP every 16,500 bases. For comparison, an average of one heterozygous SNP per 309 bases was reported in herring (Martinez Barrio et al., 2016), one per 500 in Atlantic cod (Star et al., 2011), and one per 750 bases in Coho and chinook salmon (Koop, 2018). This is at least 5 – 10 fold less variation than is seen in humans (the 1000 Genomes Project Consortium, 2015). We observed a recently described master sex-determining gene, amhby, in three western North American populations but not in populations east of the Continental Divide. We could not resolve any signals indicating a genetic sex determination system was present in populations from southern Manitoba or the St. Lawrence River. This may indicate that environmental sex determination is at play in these populations. We found evidence of a possible female-heterozygous, male homozygous ZW-ZZ genetic sex-determination system in New Jersey Northern Pike. With the highest average of 181,268 heterozygous SNPs genome wide and the greatest Ho (0.3228) of all populations, as well as the presence of the sex-determining gene amhby indicate that Northern Pike from our Alaskan population are the oldest in North America. Fewer numbers of heterozygous SNPs (61,073), low Ho (0.0922), and the absence of amhby in Northern Pike east of the Continental Divide suggests that these are relatively young populations and are descended from a small founding population. These results imply that Northern Pike first came to North America through Beringia and colonized its North American range from there, possibly via pro-glacial lake formation and drainage. However, from the data herein it was not possible to trace how re-colonization occurred after the final retreat of glaciers at the end of the last ice age. This thesis provides a genetically high-resolution snapshot of Northern Pike population structure in North America. It demonstrates that organisms with largely homogenous genomes can be incredibly successful and resilient. Finally, it adds to the complex subject of sex determination in fish and provides insight into a sex determination system in transition. / Graduate / 2020-10-15

There is concern regarding exposure of aquatic organisms to chemicals that interfere with the endocrine system. Disruption of the endocrine system can lead to impacts on sexual development, altered hormone levels, intersex, and ultimately reproductive failure. While effects of endocrine disrupting chemicals (EDCs) on standard laboratory species have been subject of intense study, to this day there is a large gap in knowledge and a high degree of uncertainty regarding the sensitivity of wild fish species to these compounds. One of the main concerns with current toxicity testing approaches is that they require the use of a large number of live animals, particularly when working with native species. Therefore, the aim of this study was to develop in vitro tissue explant assays that would enable the assessment of the sensitivity of different wild fish species native to North America to the exposure with EDCs. Specifically, two in vitro assays were developed: 1) A liver explant assay to assess effects of EDCs that can interact with the estrogen receptor (environmental estrogens), and 2) a gonadal explant assay to assess effects of EDCs on sex-steroid production. The test species selected were northern pike (Esox lucius), walleye (Sander vitreus), and white sucker (Catostomus commersoni) that were sampled from Lake Diefenbaker, Saskatchewan, Canada, and white sturgeon (Acipenser transmontanus) that were randomly selected from an in house stock reared from eggs. Liver tissue was excised from male fishes and exposed for 24 h to a synthetic estrogen, 17α- ethinylestradiol (EE2). Transcript abundance of vitellogenin (VTG), estrogen receptor (ER) α and β in liver tissue were quantified using qPCR. Gonad tissue from both male and female were excised and exposed for 24 h to a model inducer (forskolin) and inhibitor (prochloraz) of steroidogenesis. 11-ketotestosterone (11-KT) and estradiol (E2) were quantified in media by use of ELISA. Exposure to EE2 resulted in a concentration dependent increase in VTG in all species, and an increase in ERα in northern pike. Walleye males showed the greatest sensitivity to EE2. Gonad tissues exposed to forskolin showed a concentration dependent increase in 11-KT and E2. Exposure to prochloraz resulted in a decrease of 11-KTand E2. Male and female white sucker showed greatest sensitivity to forskolin, while male and female walleye showed greatest sensitivity to prochloraz. The seasonal time point during which gonad explants were excised and exposed had an impact on the potency and magnitude of response, resulting in a seasonal effect on sensitivity. Also, gonad explants from these species were found to have greater sensitivity than responses previously reported for in vitro explants of other fish species such as the fathead minnow (Pimephales promelas), and stable cell lines currently used as screening applications to detect chemicals that might disrupt the endocrine system. Therefore, current approaches that use stable cell lines or tissue explants from standardized small bodied laboratory species might not be protective of some wild fish species. These tissue explants represent a promising approach to help understand species sensitivity to EDCs, and if appropriately validated, could be a powerful tool for chemical screening.

Within my diploma thesis I have been trying to resolve the possibilities of optimization of artificial incubation of eggs and embryos in northern pike (Esox Lucius L.) under controlled conditions during three different experiments. In the first experiment was investigated the effect of three different semination solutions to the success of incubation of eggs and embryos in northern pike. I watched the survival of eggs and embryos, larvae hatching abnormalities and biometrics of larvae. It was found that the best overall results were achieved with semination solution composed of 15 ml of chemical crystalic urea per 1 liter of water, with an appropriate amount of abnormalities and highest larvae survival. In the second experiment were performed manipulation with developing eggs at given time intervals after fertilization of eggs. I watched the survival of eggs and embryos, abnormality and biometrics of hatched larvae. It was found that the lowest survival, abnormalities, and smallest TL and W were reached during manipulations within 24 hours after fertilization. In the third experiment was investigated the effect of water temperature on the length of the incubation of eggs and embryos in northern pike. With regard to the overall survival, larvae hatching, abnormalities and size of larvae achieved the best results temperatures 6 and 10 ° C. Conversely, it is entirely unsuitable for incubation temperature of 3 ° C (lowest survival, large amounts deformities). Different incubation temperatures have also confirmed the effect of water temperature on biometrics of hatched larvae.

Northern pike (Esox lucius L) populations have been declining along the east coast of Sweden, including the Gävleborg coast. This negative trend is believed to be caused by factors related to pike recruitment including loss of suitable spawning habitats. The purpose of this study is to gain a deeper understanding for the recruitment process of pike by investigating their preferences when selecting spawning habitats. Data from a rod fishing inventory targeting adult pike was used to estimate pike densities in 20 assumed spawning bays along the coast of Gävleborg. By using the number of pike caught per hour as a measure of pike density I examined how the morphological characteristics of bays and fish communities influenced pike densities during the spawning period in the studied bays. The results suggest that the density of pike (# caught per hour) tend to increase in bays with deeper average depths, larger surface area, and higher densities of sticklebacks. These results contradict the hypothesis in the study and somewhat previous research. Possible explanations for these unexpected findings are discussed, and one theory suggest that the rod fishing method used may have influenced the results. Probably improvements can be made to make the density estimates from the fishing inventory more accurately, especially when comparing bays of varying sizes. Suggestions for enhancing density estimation include adjusting the fishing duration based on bay size or using a specific number of throws per casting rod and defined surface area and then move to next surface area.

No description available.