Thesis (Ph. D.)--University of Washington, 2005. / Vita. Includes bibliographical references (p. 310-318).

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The ecological niche of a population is dynamic and will be affected by changes in the ecosystem and as a population migrates. An ontogenetic niche shift can also occur as organisms grow and can include changes in morphology, habitat, and feeding behaviour. Although they are the two most abundant salmon species, and are further augmented through hatchery stocking, it is unclear the degree to which the niches of juvenile pink salmon (Oncorhynchus gorbuscha) and chum salmon (O. keta) overlap. Furthermore, juvenile pink salmon and chum salmon undergo a period of rapid growth during their first summer at sea and it is unclear how their ecological niche changes with their ontogeny. Understanding the foodweb dynamics of juvenile salmon in the coastal marine environment is important because a large proportion of the overall mortality of salmon is thought to occur during their first summer at sea. The purpose of this study is to determine the degree to which the niches of juvenile pink salmon and chum salmon overlap, how their trophic position and food source changes as they grow into a new ontogenetic niche, and how these processes are affected by ocean conditions. I expected that years of poorer feeding conditions and increased competition would result in reduced trophic position and greater overlap of the niches of juvenile pink salmon and chum salmon. I hypothesized that juvenile salmon would shift their diet to a more offshore-based foodweb as they grew and that their trophic position would increase with size, but that the shift would be stronger when feeding conditions were improved. Statistical analysis showed evidence that the overlap of the niches of pink salmon and chum salmon increased when the abundance of salmon was high. Contrary to expectations, the trophic position of salmon appeared to decrease under favourable conditions. The trophic position of both pink salmon and chum salmon was higher in the southern portion of the study area, and increased when juvenile abundance was high. I suggest that the higher trophic position among juvenile salmon when there is more competition might result from increased reliance on gelatinous zooplankton, which are carnivorous, but a nutritionally poor food choice compared to other common prey items. The ontogenetic shift from summer to fall among juvenile salmon included a shift to a more offshore-based diet and a higher trophic position. In the northern portion of the study area, which was comprised of the southern reaches of the Alaska Coastal Current (ACC), the shift to an offshore-based food source was more pronounced than the trophic shift. In the southern portion of the study area, which included the Transition Domain (TD) between the ACC and the California Current System (CCS), the shift to a higher trophic position was more pronounced than the shift in food source. The results of this study suggest that if climate change leads to poorer feeding conditions, the niches of pink salmon and chum salmon may increasingly overlap when the abundance of these species is high. Hatchery stocking of these species may also contribute to this trend if it leads to a greater abundance of juvenile salmon in the coastal marine environment. There is evidence that the structure of the food web and the nature of the ontogenetic niche shift are very different in the ACC and the TD, and climate change and hatchery stocking will most likely affect these regions differently. / Graduate

Coho salmon (Oncorhynchus kisutch) rely on unique habitats during the winter season, which may dictate how much individuals may grow and when migration from freshwater rearing habitat to the ocean occurs. Here I analyze movement timing and growth patterns for coho salmon through a field-based study and a literature review. For the field portion, I examined hatchery-stocked juvenile coho salmon across four stream basins in the Russian River watershed, California to determine the relative importance of climate, landscape, and fish size metrics in predicting movement and growth patterns over a winter rearing and spring smolt outmigration time period (December 2014-June 2015). I observed three unique movement strategies: winter parr movement, spring smolt movement, and inter-tributary movement. Movement was predicted in relation to daily temperature and precipitation, followed by in-stream and upslope basin conditions in random forest modeling. Specifically, fish that moved later were associated with basins that contained higher productivity and low-gradient floodplain habitats, while fish that moved earlier came from streams that lacked invertebrate prey and had limited low-gradient rearing habitat. Fish size and timing of movement were the primary predictors of growth, with relatively larger fish in the spring growing faster than fish that were relatively smaller prior to winter. These relationships suggest that hatchery-release fish are still highly influenced by environmental conditions once released, especially in terms of initial seasonal movement, and that watershed conditions should be considered when utilizing hatchery-rearing programs to supplement wild fish populations. In North America, coho salmon populations are distributed from Alaska through California, and may exhibit unique movement and growth patterns in relationship to population-scale vulnerability (Endangered Species Act listing), basin area, and availability and types of rearing habitat. For the second part of my thesis, I conducted a literature review to assess what factors are commonly considered in predicting movement and growth patterns for these fish, as well as the types (season and life stage) and number of movement strategies reported. Eighteen studies were summarized, of which sixteen identified unique movement strategies, ranging from one to four. Despite a wide range of basin areas and latitudes, winter parr and spring smolt movements were commonly observed, with authors primarily relating these behaviors to in-stream habitat and fish size metrics. Additionally, growth was linked positively and primarily with off-channel winter rearing, which may outweigh the importance of fish size in predicting growth when high quality rearing habitats are available during the winter season. Recognizing movement timing diversity and its drivers can help recover threatened coho salmon populations. More widely distributed populations may have unique phenotypic expressions based on localized genetic and environmental interactions, increasing diversity and overall stability across the population, a concept known as the portfolio effect. Understanding fish-habitat relationships can aid recovery efforts by providing a framework of climatic and watershed conditions that support unique behaviors, even in already severely limited populations.

Coho salmon (Oncorhynchus kisutch) from six hatcheries operated by the Canadian Department of Fisheries and Oceans Salmonid Enhancement Project, were reared in a common facility and then subjected to a series of standardized challenge tests. Results suggest that there are genetically based differences in the response to stressful challenges among stocks of coho salmon from southern British Columbia. The challenge tests were: saltwater (30ppt); saltwater and an increase in temperature (30ppt and 4°C); high pH (9.4 and 10.0); low pH (3.55, 3.65, 3.75 and 4.1); thermal tolerance (1°C/h); and handling (30s netting). The measured parameters were plasma sodium and chloride ion concentrations for the saline and pH challenges, time to dysfunction in the thermal tolerance challenge and plasma glucose concentration in the handling challenge. No differences among stocks were found in responses to the high pH and thermal tolerance challenges. The Chehalis River stock had the smallest plasma ion increase in salt water but showed the largest plasma ion decrease in acidic waters. In some of the low pH challenges the Tenderfoot Creek stock showed less plasma ion loss than other stocks. The stock from Eagle River had the lowest plasma glucose concentration increase during handling challenges. The combined saltwater and temperature increase challenge demonstrated the cumulative effect that stressors can have. Sampling associated with the handling challenges revealed a diurnal fluctuation in resting plasma glucose concentrations. The low pH and handling challenges showed that stock performance and the magnitude of the response observed varied with rearing conditions. Although there was some variation in the magnitude of the stock response to challenges between the two rearing conditions used, differences among stocks were consistent. When the response to all challenges were assembled into a relative challenge response profile (or performance profile), each stock was unique. / Land and Food Systems, Faculty of / Graduate

The influence of temperature and activity on certain cardiovascular and respiratory parameters in adult sockeye salmon was studied. Cannulae were implanted in the dorsal aorta and buccal cavities of fish which were forced to swim in a tunnel-type respirometer until they fatigued. Three groups of fish were acclimated and tested at 5, 15, and 22°C respectively. Pressures recorded from the dorsal aorta and buccal cavity gave information about heart rate, blood pressure, pulse pressure, ventilation rate and pressures in the buccal cavity before, during and after the fish were fatigued by swimming. Hematocrit data revealed the blood oxygen capacity of these fish, to be approximately 9 vols %. Knowledge of the blood oxygen capacity, heart rate and the metabolic rates of adult sockeye at various temperatures and levels of activity allowed calculation of stroke volume and cardiac output by the Fick principle. During successively greater swimming activity heart rate and blood pressure rose in all three test groups while ventilation rate was highly variable. Calculated stroke volume and cardiac output increased markedly and it is suggested that the peripheral resistance of the vascular system diminished during exercise. The increase in heart rate during exercise is thought to be related to a release of vagal tone or possibly, to the presence of circulating catecholamines. Elevated dorsal aortic pressure during activity was undoubtably the result of elevated cardiac output. Since dorsal aortic pressure did not increase in accordance with the increases in oxygen uptake observed during activity it is suggested that peripheral resistance decreases in the face of elevated cardiac output. Post-exercise ventilation rate approached resting levels within one hour after fatigue but heart rate and buccal pressure remained above resting levels. High post-exercise heart rates and buccal pressures were believed to be evidence for the presence of an oxygen debt. Blood pressures fell below resting levels in the 15 and 22°C test groups following fatigue and remained low one hour after fatigue. These low pressures may indicate that vasodilation of peripheral vessels had occurred to facilitate flushing of the muscles with blood and aid in the elimination of oxygen debt. Temperature appeared to directly influence heart rate of both quiescent and active fish. Higher acclimation and test temperatures produced higher heart rates than lower acclimation and test temperatures. Presumably temperature influences heart rate by acting directly on membrane phenomena in the myocardium. No cardiac failure was observed in sockeye, even at 22°C during severe exercise. Routine and active oxygen uptake increased with temperature but the rate of increase of active oxygen uptake decreased with temperature - possibly because of the low availability of oxygen in warm water. Temperature appeared to directly influence the ventilation rate of quiescent fish. Higher temperatures were accompanied by high ventilation rates, undoubtably as a result of increased routine metabolic rate at high temperatures and scarcity of oxygen in warm water. / Science, Faculty of / Zoology, Department of / Graduate

Innate species-specific temperature preferences of fish are subjected to fluctuations under a variety of environmental, physiological, and developmental conditions. The temperature preference patterns of two ecologically distinct races of chinook salmon (Oncorhynchus tshawytscha) were investigated as laboratory held animals underwent smoltification. Smoltification is a distinct developmental stage in the life history of anadromous salmonids when juvenile fish undergo profound behavioral, morphological, and physiological differentiation prepatory to seawater entry. A group of spring and fall chinook salmon were held under identical conditions of increasing water temperature over the course of smoltification. Another group of spring and fall chinook salmon were held at a constant water temperature of 8° C over the same period of time. Changes in the preferred temperature of juvenile chinook salmon were associated more closely with the size (fork length) of fish than with time (days). Both spring and fall chinook salmon held at 8° C showed an increase in thermal preference of about 1° C as fork length increased in these respective groups. This increase in thermal preference is thought to be thermoregulatory, accelerating smolt development in fish held in inhibitory low water temperatures. Spring chinook salmon held at increasing water temperatures showed no change in thermal preference associated with smoltification. Fall chinook salmon held at increasing water temperatures displayed a large drop in thermal preference towards the end of smolt development. Differences in the thermal preference patterns of spring and fall chinook salmon during smoltification may result from local habitat adaptations, as well as seasonal differences in smolt migration.

This study examined the movement, habitat utilization, growth, and survival of hatchery incubated chinook salmon (<i>Oncorhynchus tshavvytscha</i>) fry stocked above a barrier falls on the Indian River, Chichagof Island, southeast Alaska. The Indian River contained significant potential salmonid rearing habitat, but was devoid of anadromous fish upstream of the barrier falls near tidewater. Approximately 50,000 and 260,000 chinook fry were stocked into Indian River in 1986 and 1988, respectively. The stream was divided into reaches which were stocked with equal numbers of fry. In 1988, fry also were stocked into beaver ponds connected to the stream. Each group of fry contained coded-wire tagged individuals, identified by stocking location. Fry movement was almost entirely downstream, with a substantial emigration during a spring flood immediately after the 1988 stocking. Most emigrating fry had been stocked in the lower stream section. / Master of Science

Fish meals (FM) and fish oils (FO) are used extensively as the main protein and lipid sources respectively in industrially compounded salmon feeds, mainly due to their excellent nutritional properties. Nevertheless, several reasons dictate the utilisation of sustainable alternative protein and lipid sources and the subsequent reduction in the reliance on fishery-products in aquafeeds. Soy protein concentrate (SPC) is a very promising alternative to FM Hence, the main objective of the present thesis was to investigate the effects of the increased substitution of FM withSPC, lysine and methionine on the growth performance and immune responses of early and late stage Atlantic salmon parr prior to and after vaccination with commercial vaccines (Experiments II and V presented in Chapters 4 and 6). Furthermore the effects of increasing dietary levels of SPC with consistent and/or increasing dietary supplementation of phosphorus on the Atlantic salmon parr’ body proximate and mineral composition or the skeletal mineral composition respectively, prior and post-vaccination with commercial vaccines; under continuous light or under 12 hours light: 12 hours dark photoperiod (Experiments I and V presented in Chapters 3 and 5 respectively). Lastly the impact of FM-, FO- and fishery-free diets on the growth, carcass proximate composition and immune status of Atlantic salmon post-smolts was investigated (Experiment III presented in Chapter 7). In the latter experiment six diets were tested including: two commercially applied marine based diets, one with partial inclusion of vegetable proteins (VPs) and oils (VOs) according to the EU standards (2011-12) (MBE) and one with partial inclusion of VPs, VOs and land animal-by product (ABP) proteins according to the non-EU standards (MBABP); a fully vegetable protein (VP) diet; a fully algal and vegetable oil (VO) diet; a marine-free VP and VO and algal oil diet (VP/VO) diet; and a marine-free diet with a mix of VPs and land ABP proteins and lipid from VOs and algal oils (MFABP). The results of the Experiments I and II (Chapters 3 and 4) show that late Atlantic salmon parr can grow efficiently on SPC80 diets, however, they require longer periods to adapt to these diets compared to fish fed diets containing lower levels of SPC as a protein source. Decreased mineralisation of body cross-section was observed for salmon fed increasing dietary SPC. Vaccination improved mineralisation for the high dietary SPC salmon groups. However, continuous light exposure promoting fast growth appeared to be detrimental for Atlantic salmon body cross ash, Ca, Mg, Mn, P and Zn. Moreover, it was demonstrated that substitution of up to 50% of high quality FM protein with SPC and constantly added P has the minimum possible impact on late salmon parr growth, whereas it stimulates several immune parameters prior to immunisation. Immunostimulatory effects were also shown for the diets with higher dietary SPC levels. It is not clear if these results were an effect of increased FM replacement with SPC or not properly balanced levels of dietary P. The Experiments III and IV (Chapters 5 and 6) illustrated that early stage Atlantic salmon parr can accept diets with up to 58% protein from SPC without serious effects on body growth. However, higher levels can severely affect salmon growth performance. Moreover, it was shown that long-term feeding of salmon with increasing dietary SPC combined with increasing phosphate supplementation, alone or in combination with vaccination can actually be beneficial for Atlantic salmon parr bone mineralisation. However, mineralisation in vaccinated fish was higher than in PBS-injected fish. This could be linked to the slower growth of vaccinated salmon allowing their developing bones to mineralise properly. Changes in the modulation of the different components of the complement activity was revealed in Atlantic salmon fed increasing dietary levels of SPC. The modulation of complement activity was demonstrated at both studies utilising increasing dietary SPC concentrations, indicating that complement componenets are among the most prominent immunological markers upon dietary FM replacement with SPC. However, overall no differences in total complement activity and therefore the immune capacity and resistance against Aeromonas salmonicida were observed among the salmon groups receiving increasing levels of SPC. Lastly in Experiment V (Chapter 7) higher growth performance indices (weight gain, SGR and TGC) were evident in the MBE salmon compared to the MBABP group, salmon fed diets with complete eleimintion of FM or FO (VP and VO respectively) and fish fed two diets with total substitution of both marine derived feed ingredients, three months after the start of the feeding trial. Higher feed intake was demonstrated for both MBE and VP salmon compared to the other groups for the duration of the first period. The above results could have been influenced by discrepancies in the size of the fish at the start ofthe trial, revealing flaws in the experimental design. Both MBE and VP salmon groups also presented the highest feed conversion ratios, revealing the lowest efficiency in dietary nutrient utilisation in comparison to the rest of salmon which exhibited no differences in feed efficiency, revealing an overall better performance of the MBABP and diets with low levels of marine feedstuffs. Improved FI compared to the values of the first period and higher SGR and TGC values were demonstrated for salmon from the latter treatments compared to MBE and VP salmon, during the second part of the study, revealing compensatory growth for these groups. VP salmon demonstrated the highest and VO salmon the lowest condition factor values. The former finding might possibly be related with higher fat accumulation in the viscero-hepatic tissues. No differences were observed in carcass moisture, protein, fat and ash concentrations among the dietary groups of fish. Furthermore, no differences were demonstrated in terms of total and differential leucocyte counts, plasma haemolytic activity, plasma protein and total IgM levels, stimulated and non-stimulated HKM burst activity among the different dietary groups. However, lower haematocrit values were observed in the MB and VO-fed groups compared to the MFABP and VP/VO groups. Furthermore, decreased lysozyme activity was observed for all diets in contrast to the control groups, whereas FM-free diets promoted plasma anti-protease activity. The former result could have been an effect of either immune or stress induction, whereas the second is regarded as an immunostimulatory effect. The results suggest that marine-oil, marine-protein and marine-free diets could be satisfactorily used for Atlantic salmon post-smolts without severe reductions in their innate immune responses, although longer adaptation periods might be required for the fish to fully accept these diets.

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