In the following study, I tried to link hormonal background conditions to successful olfactory imprinting in sockeye salmon by employing behavioural, endocrinological and electrophysio logical experiments. In the initial experiments, sockeye salmon were exposed to potential imprinting odorants, with or without additional treatment with thyroid hormones, during several juvenile stages between fertilization and beyond the PST. After two years of rearing, these fish were tested for behavioural responses to test odorants in two behavioural arenas. Neither immature nor mature fish reacted behaviourally to the odorants that they had been exposed to previously. Therefore, exposure of juveniles to odorants did not lead to imprinting to those odorants under hatchery rearing conditions. In contrast, juvenile fish that were exposed to test odorants and treated with a combination of T₃ and T₄ (in all cases) or T₃ (in one case) the two most common forms of thyroid hormones, did exhibit an odorant recognition response two years later. However, the response differed between immature and mature fish. Mature fish were attracted to the imprinting odorant, whereas immature fish were repelled by the it. When immature fish were injected with GnRH before testing, their behavioural response was reversed. No behavioural response could be detected in fish that had been challenged with either T₃ or T₄ alone, in contrast to a combined treatment with both forms. Thus, I found evidence that a combination of T₃ and T₄ initiated imprinting and that GnRH motivated odorant recognition. To examine the underlying hormonal processes, I first determined plasma thyroid hormone concentrations in sockeye salmon before and after hormonal challenges with thyroid hormones or GnRH. In addition, the activity of the deiodinase enzyme that converts T₄ into the other possible forms of thyroid hormones was investigated in sensory and non-sensory tissues. The results suggested that only a combined T₃T₄ treatment increased the availability of both thyroid hormone forms in blood plasma, while a separate challenge with T₄ suppressed T₃ availability and vice versa. Moreover, the results provided evidence for deiodinase activity in the olfactory epithelium and the retina and demonstrated that GnRH can modulate the T₄ conversion process. This inform ation was helpful for planning and interpretation of the remaining experiments. Results obtained from a classical conditioning paradigm (heart-rate-conditioning), provided support for the hypothesis that GnRH lowers the threshold to an imprinting odorant and that the influence of GnRH was not restricted to an enhancement of motivation. To investigate whether hormonal action could also modulate the sensitivity of the peripheral olfactory system, electrophysiological responses from the olfactory epithelium (electro-olfacto-grams or EOGs) were recorded. The EOG results established that thyroid hormones and GnRH increased the EOG response of adult naïve (never imprinted to an odorant) fish, as did maturity. In the last experiments, I conducted EOG recordings on fish that had been imprinted at a juvenile stage. In summary, EOG recordings revealed that the imprinting process increased sensitivity to the imprinting odorant at maturity, while sensitivity in immature fish was decreased in comparison to non-imprinted fish. In combination with my behavioural results, this could explain why salmon do not enter their natal stream before they reach maturity. At maturity however, I also encountered desensitization to non-imprinting odorants, which might increase the ability to focus the olfactory system to the task of homing. / Graduate

Trade with salmon has been increasing in Czech. The aim of this work is to show the trend in trade of salmon. Find out the statistics of import of this commodity. Find out, how reachable is salmon in Czech retail shops.

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The early marine period for juvenile salmon is a critical life history stage for growth and survival. The health of near-shore ecosystems where juvenile salmon spend their early marine life, and the capacity of these habitats to provide prey are thus important for overall salmon returns. While near-shore habitat is generally accepted as being of critical importance, few studies have examined how juvenile salmon use this habitat during their early marine life. Understanding the trophic dynamics in these ecosystems and the characteristics of these habitats that are important for food provision will help us gauge the value of near-shore areas to the early marine phase of juvenile salmon. The importance of this avenue of research is underscored by declined rates of early marine survival of salmon, and suggestions that the rapid development of the shoreline is contributing to this decreased survival. My project investigates the role that near-shore habitat plays in promoting growth and survival of juvenile salmon by evaluating eelgrass as foraging grounds for juvenile salmon in the Comox Estuary, British Columbia. In 2015, we compared juvenile Chum salmon diets to prey availability in zooplankton tows and in epifaunal and infaunal eelgrass samples across a gradient of eelgrass shoot density. We complemented diet analysis with the use of stable isotope ratios of carbon (δ13C) and nitrogen (δ13N) to examine the relative contribution of zooplankton, eelgrass, and terrestrial invertebrates to juvenile Chum salmon diet. In 2016, we collected additional eelgrass samples to cover a wider range of eelgrass density, and compared juvenile Chinook salmon diets to prey availability in eelgrass. Prey invertebrates, such as polychaete worms, harpacticoid copepods, and amphipods, increased with eelgrass shoot density. Juvenile Chum salmon and juvenile Chinook salmon assessed in this study fed primarily on benthic species, specifically on harpacticoid copepods, which were only abundant in epifaunal eelgrass samples. The abundance of prey invertebrates in eelgrass beds and the benthic diet of juvenile salmon in the Comox Estuary leads us to conclude that the presence of eelgrass is an important habitat feature for juvenile salmon. / Graduate

Climate is emerging as a primary determinant of marine survival and migratory behaviour for Pacific salmon. For example, a regime shift in the mid-1990s was correlated to a major change in the migratory behaviour of coho salmon (Oncorhynchus kisutch) in the Strait of Georgia, BC. The details of this new behaviour pattern remain relatively unknown. Furthermore, many coho stocks have been declining during the past three decades. Mitigative strategies –such as hatchery programs— have done little to reverse the trend, and little is known about how hatchery fish are affecting wild populations. The objective of this dissertation was to identify key mortality areas and provide the first look at the migratory behaviour of juvenile wild and hatchery coho in southwestern British Columbia using new telemetry technologies. As coho pre-smolts are relatively small compared with other salmonid species that are typically studied using acoustic telemetry, the identification of the appropriate sizes of fish and tags to use was critical. The first study tested the effects of surgically implanting the three smallest sizes of acoustic tags available on the growth, survival, performance and condition of coho pre-smolts. The first of three field studies to follow investigated the early migratory behaviour and survival of an endangered coho population. The second field study examined differences in physiology, survival and migratory behaviour between wild and hatchery-reared coho smolts. Finally, the third study analysed the altered marine migratory behaviour of juvenile coho in the Strait of Georgia. This dissertation provides the first evidence of high freshwater mortality rates in the endangered coho population, which has implications for the management and conservation of this and other at-risk stocks. I found differences in migratory behaviour and physiology between wild and hatchery-reared coho, suggesting that mitigative strategies need further evaluation. Finally, the timing of the anomalous coho migration out of the Strait of Georgia confirmed that population changes in the strait are a consequence of ecosystem-related impacts. These findings demonstrate how new technologies could be used to fill major information gaps and improve the management and conservation of Pacific salmon. / Land and Food Systems, Faculty of / Graduate

This dissertation addresses the relationship between large-scale dam removal and the nearshore ecosystem function for fish. The work is based on almost a decade’s worth of collaborative field work in the nearshore of the largest dam removal in the world recently completed on the Elwha River. The data analyzed span seven years prior to, during, and throughout the first year of each dam removal (January 2008 to November 2015). As of September 2015, approximately 2.6 million m3 of sediment material increased the area of the Elwha delta to over 150 ha. Long term study of fish in the estuary reveals fish community response to dam removal, and indicates likely interactions in the nearshore between hatchery and wild fish, including chum salmon critical to watershed recovery. Continued hatchery releases may therefore further challenge chum salmon recovery, and this interaction should be considered when planning for future watershed recovery. Community analysis revealed that, while species richness and taxonomic diversity do not appear to have a significant response to dam removal, functional diversity in the nearshore does respond significantly to dam removal. Three main shifts occurred in the nearshore: large scale and rapid creation of estuary habitats; delivery of large amounts of sediment to the delta/estuary in a short period of time, and; a shift in original habitats from tidally influenced to non-tidally influenced habitats resulted in changes in estuary function. Changes in functional diversity occur disproportionately in the new sites, which have more unstable, and so less resilient, communities. Functional diversity in the original estuary sites appears to be more resilient than in the newly created sites due to the large-scale environmental disruption that, ironically, created the new sites. However, the functional diversity at the original sites may be defined in part by management activities, including hatcheries that could mute/mask/inhibit other community responses. Further, functional diversity at the newly formed nearshore areas is predicted to stabilize as the habitats are vegetated and mature. Principal components analysis of Elwha fish community over the course of this study reveals that the fish communities of the Elwha are predictably grouped, indicating that while a few new species are observed, dam removal has not resulted in observable disruptions in fish community assemblages. And finally, nearshore habitats are critical for many forage fish species, and an emerging topic for large-scale dam removals. Forage fish spawning response to dam removal appears to be complex and may be related to multiple factors including high interannual variability in physical habitat conditions, geographic factors and complex life histories of forage fish. Habitat suitability for forage fish spawning should increase as restored ecosystem processes and newly created habitats mature and stabilize, indicating that time may be an important factor in nearshore restoration for forage fish spawning. It is therefore important to implement long-term monitoring and incorporate nearshore ecosystem process and function for multiple life history stages of nearshore species, including forage fish, into large-scale dam removal restoration and management planning. / Graduate / 2019-04-12

Many rivers are affected by man-induced regulations of stream-flow. The effects of these on the instream biota have been studied widely and it is generally accepted that assessment tools for the management of regulated rivers are of vital importance. In particular predictive instream habitat models like the Physical Habitat Simulation Model (PHABSIM) have become popular for this purpose with users world-wide. These models predict discharge-related changes in instream habitat availability for target species by modelling the hydraulic geometry of the river reach on the one and the microhabitat preferences of the species on the other side. Despite their popularity, validation studies for this approach have met many difficulties which are mostly related to the biological part of the model, the habitat preference curves. A review of these studies undertaken here reveals that very little information has been published on two main assumptions of the models: 1. The habitat preference of a species is independent of stream discharge 2. The habitat preference of a species is independent of the species population density Most validation studies are undertaken in field situations. As such they frequently have had problems relating to sampling the microhabitat use consistently, a lack of experimental control and variations in other secondary variables. It was thus decided to conduct controlled experiments in a large indoor flume. Young-of-year Atlantic salmon (Salmo salar) caught in a nearby stream were stocked into pool-riffle sequences, landscaped within a natural substrate, in observation areas of 3.6 metres length and 1 metre width. Microhabitat use of fish was recorded at three different discharges within a 15-fold discharge variation. It was found that the mean column velocity preference of the juvenile salmon, calculated by the standard method, varied largely, mainly due to a shift of preference for low water velocities. "Weighted usable area" (WUA) calculations, the final output of instream habitat models, varied up to two-fold due to these differences in preference. Habitat preference also varied with population density. Fish preferred the riffle habitat at low population density and the pool habitat during high population density. Fish used higher mean column velocities during low population density. There are hence fundamental problems related to the approach of using density functions as preference indices as is commonly done for building habitat preference curves, because of a bias for habitat availability. A new approach using Geographic Information Systems (GIS) is taken by comparing the microhabitat conditions fish experience at their chosen positions with the conditions fish would have experienced had they maintained the positions used at the other discharges. It was found that fish adjusted their positions towards significantly different microhabitats between low flow positions and the positions at the other two flows. This research demonstrates how microhabitat use and preference of wild-caught juvenile salmon varied with discharge and population density in a large near-natural flume. The error introduced by these variations to instream habitat model predictions was large. It confirms that habitat preference curves built as density functions on empirical fish observation data are bound to misrepresent the overall habitat requirements of a species life stage which in the case of juvenile salmon appeared wide and flexible over the range of discharge.

Determining the physical and biological habitat variables that influence the abundance of juvenile salmonids in British Columbia streams will improve management practices. Habitat models are tools that provide insight into organisms’ habitat needs and provide a more efficient mechanism for estimating population abundance than direct measurement. Models have been developed for salmonids in other jurisdictions, but very few have included invertebrate drift (a primary food source for juvenile salmonids) as a predictive variable. This is because temporal and spatial variation of drift abundance are widely assumed to be so high that drift cannot be reliably estimated without unreasonable effort. This thesis investigates the temporal and spatial variability of invertebrate drift and the impact of its inclusion in habitat models for juvenile salmonid abundance in two chapters. The first objective of the first chapter was to evaluate the temporal variability of invertebrate drift by comparing the seasonal and day-to-day variation in drift abundance to spatial variation within and between sites. The second objective was to develop predictive models for invertebrate drift abundance. Aquatic, terrestrial and total invertebrate drift abundances varied primarily between sites and very little between days or months at the same site, indicating that a single day of sampling is sufficient to assess drift abundance for comparison among sites. The abundance of invertebrate drift was related to productivity- and flow-related habitat variables. The objectives of the second chapter were to develop predictive models for juvenile salmonid abundance in southwestern BC using physical and biological habitat variables, to determine whether habitat variables differ between the Coast and Interior regions of BC, to determine the contribution of invertebrate drift to the relative predictive ability of the models, and to determine cost:benefit ratios for the predictive models and their component variables. The final models for predicting abundance of all young-of-year salmonids combined, and rainbow trout (Oncorhynchus mykiss) and coho salmon (O. kisutch) individually, included variables related to stream structure and productivity, and the models for rainbow and coho showed regional differences. Invertebrate drift did not improve model fit. / Science, Faculty of / Zoology, Department of / Graduate

Degradation of streams in urban-rural fringe regions occurs through complex interactions between hydrological, physical, chemical and biological mechanisms of the stream environment and surrounding landscape. Biological monitoring using macroinvertebrates may capture the complex and cumulative influences of land activity on the stream environment. The Salmon River catchment in the township of Langley, British Columbia, Canada straddles urban and rural environments in the Lower Fraser Valley. To date the Salmon River catchment has been subject to several environmental surveys. Following these earlier investigations, this study quantified relationships between the stream environment and changing land activity, across multiple scales, from 1975 to 2005, using macroinvertebrates as environmental integrators. Current and historical water, sediment, and macroinvertebrate information along with land use and land-cover evaluations were used to quantify relationships between the macroinvertebrate community and land activity in the catchment. Spatial and seasonal results for specific conductivity (a total dissolved ion indicator) and NO₃⁻-N and PO₄³ (nutrient indicators) traced groundwater and overland inputs to the stream environment. Nitrate guideline exceedances occurred at groundwater-influenced sites. Elevated sediment trace metal concentrations and Zn guideline exceedances occurred mid-reach in the catchment. Peak total macroinvertebrate and sensitive taxa abundance occurred mid-reach in the catchment in 2005, while richness and proportional sensitive abundance peaks were seen at groundwater-influenced sites. The dominance of tolerant to moderately pollution tolerant taxa occurred throughout. Despite historical water quality concerns at groundwater-influenced sites, greater shifts in community composition occurred in headwaters regions. Patterns of land use and land cover changed in sensitive areas (i.e. above aquifer and in the headwaters). A greater number of correlations between land activity and macroinvertebrate measures occurred at streams sites with 100 m buffers. The abundance of sensitive taxa positively correlated with the amount of agricultural land use, while rarefaction declined. Several Macroinvertebrate functional feeding groups correlated positively to forest cover, while sensitive taxa abundance and Zn concentrations declined. Results suggest continued water quality and sediment trace metal concerns, while macroinvertebrate results point to nutrient enrichment and greater historical variability in headwaters regions. Agricultural activity appears to have a stronger influence on aspects of the stream environment despite the presence of urban-rural land activity. / Science, Faculty of / Resources, Environment and Sustainability (IRES), Institute for / Graduate

Recognition and use of indigenous knowledge in resource management can increase the information available about the resource and facilitate establishment of a larger management role for local resource users. This paper examines the use of indigenous knowledge in resource management using the case of knowledge of Pacific salmon {Oncorhynchus spp.) among the Upper St'at'imc, near Lillooet, British Columbia (B.C.). Salmon in the study area are currently managed by the federal Department of Fisheries and Oceans (DFO). This system was established in the 1940s and overlays a traditional management system consisting of fishing site ownership, a well-defined system of access to sites, rules of conduct at fishing sites for the catching and processing of fish, and harvest restrictions. Recent DFO policy changes, signified by the Aboriginal Fisheries Strategy, indicate a movement toward a larger management role for First Nations. This study addresses what indigenous knowledge is available, how it compares to knowledge used by the Department of Fisheries and Oceans, and how indigenous knowledge can be used in modern salmon stock management. A literature review was supplemented by interviews with elders, young Upper St'at'imc leaders, and both DFO and non-DFO biologists. Current indigenous knowledge pertains to salmon stocks, habitat, and practices and philosophy. Indigenous knowledge can be primarily distinguished from western scientific knowledge on the basis of the following properties of the indigenous system: a greater amount of qualitative vs. quantitative information; an obvious recognition and discussion of anomalies; the perception of a wide range of variables in a region; the use of specific local technology; the development of analysis based on both observations over a medium-sized area and traditional ideologies; and differences in institutional arrangements for gathering knowledge. Differences between indigenous and western scientific knowledge are related to the requirement that DFO accumulate and process a large amount of information over a very large geographical area. Several barriers exist to using indigenous knowledge in modern resource management, including the fact that indigenous knowledge does not fit readily into established methods for gathering and analyzing data. Using indigenous knowledge may be facilitated by innovations at both the local and state levels. / Applied Science, Faculty of / Community and Regional Planning (SCARP), School of / Graduate