The primary objective of this study was to identify and investigate the underlying basis for variation in the volume of exports of Canadian chum salmon during 1954-1975 period. A number of factors thought to be of importance in the determination of the volume of exports of chum salmon were hypothesized. These factors were: chum salmon price» the price of substitute commodities, the consumer income, population, general price level in importing countries, and fluctuations in exchange rates between Canadian currency and the currencies of the importing countries. The theoretical model was reformulated in terms of empirical models of demand for Canadian chum salmon in: West Germany, Sweden, and Italy. The empirical analysis focused upon the effects on annual export volume of changes in prices of Canadian chum salmon, changes in prices of salmon from other countries, and changes in consumer income in importing countries. The results suggest that: (1) in the case of Germany and Sweden, changes in prices of salmon from other countries and changes in consumer income, (2) in Italy, changes in Canadian chum salmon prices and changes in prices of salmon from other countries have been of principal importance in the determination of volume of exports of Canadian chum salmon. / Graduation date: 1979

The effects of temperatures within the optimal range for incubation of salmon, and hyperoxic and hypoxic oxygen tensions, were examined to develop an optimal path of growth during the pre- rearing stage for chum salmon (Oncorhynchus keta). During early development, and at constant oxygen tension, an elevated temperature of 55°F (12.8°C) led to accelerated growth and most efficient conversion of yolk compared to 50°F (10°C) or 45°F (7.2°C). With increased age, growth and efficiency were favored by decreasing temperature with its associated increase in oxygen concentration and reduced metabolic demand by the embryo. After hatching, the detrimental effect of a high temperature was not offset by the increased availability of oxygen and growth was retarded relative to lower temperatures. Oxygen tensions within the treatment range of 145 to 253 mm Hg did not contribute significantly to embryo weight when measured at equal stages of development in day-degrees. The optimal path for growth with minimal mortality involved a gradual reduction in temperature from 55° to 45°F during incubation, a constant temperature of 45°F after hatching to the beginning of active feeding, and an oxygen tension not in excess of air saturation. / Science, Faculty of / Zoology, Department of / Graduate

Within the environmental approach for the study of fluctuations in fish population abundance, factors that may regulate the overlap in time and space (phasing) of fishes, food supply, and predators, are sought. This trophic phasing analysis is based on the recognition that production of food is a process at least partially independent of the production of consumers. Trophic phasing analysis was applied in investigating production of chum salmon in the Fraser River estuary. Juvenile chum salmon were captured near a tidal flat; the abundance of salmon near the flat was highest in late May in 1985 and in early June in 1986. These salmon relied heavily on harpacticoid copepods as a food source. Individual taxa as well as the assemblage of main prey harpacticoids also had periods of highest abundance in the water column. The blooming period of the prey harpacticoid assemblage coincided with the appearance in the sediment of warming episodes. These warming episodes result from interactions between the daily heat cycle and specific tide patterns. Variations in the degree of overlap of the periods of highest abundance of salmon and harpacticoids could affect the survival of the fishes. The degree of overlap of those periods was hindcasted using indices for the temporal patterns of abundance of salmon and harpacticoids on the flat. The median date of downstream migration at a counting station upstream was used for the salmon; the timing of the second annual occurrence of tide conditions giving rise to a warming event in the sediment was used for harpacticoids. Difference in time between the two events was taken as a phasing index accounting for two degrees of freedom in the process of fish production. There is suggestion of a non-monotonic relationship between the index of survival of even broodyear chum salmon and the hindcasted phasing index. / Science, Faculty of / Earth, Ocean and Atmospheric Sciences, Department of / Graduate

Underyearling chum fry were held in fresh water and salt water at two different temperatures and under two different photoperiods. The first tests were made after forty days acclimation. Aggregations were greater in salt- than in freshwater (p < 0.01). At the lower temperature the fish were more aggregated than they were at the higher temperature (p < 0.05). Photoperiod effects were not significantly different. The biological meaning of these results is discussed. It is concluded that, under the conditions of this experiment, chum salmon fry show true schooling (as defined by Keenleyside, 1955) only in salt water. / Science, Faculty of / Zoology, Department of / Graduate

Thesis (Ph. D.)--University of Washington, 1981. / Vita. Bibliography: leaves [246]-271.

An integrated laboratory and field approach was used to study the behaviour and ecology of Pacific salmon (genus Oncorhynchus) alevins in the gravel. The hypothesis tested was that these yolk sac fry move throughout the gravel prior to emergence, that this movement has both lateral and vertical components, and that changes in the physical or biological environment will alter certain parameters of subgravel behaviour. Eyed chum salmon (0. keta) eggs were buried in incubation channels at Robertson Creek, B. C. Eight experimental treatments were chosen, utilizing two gravel sizes, two burial depths and two planting densities. The fry were captured at emergence by means of specially designed traps that allowed determination of degree of lateral movement, pattern of emergence and survival to emergence. The fry were also sampled for condition (weight-length ratio) at the time of emergence. In the larger gravel, survival was greater, lateral movement was increased, and initial emergence was earlier. At the greater burial depth the emergence period was longer. At the greater burial density initial emergence was earlier. Condition at emergence was the same in all treatments. The behaviour of coho salmon (0. kisutch) alevins was examined in specially constructed aquaria, where light and flow conditions were as natural as possible. The same environmental factors were varied as in the field. In addition to a general description of alevin behaviour, detailed analyses were carried out on: vertical and lateral movement, orientation, spatial distribution, condition, survival and pattern of emergence. In the larger gravel vertical and lateral movements were increased, survival was higher, area utilization was greater and condition at emergence was poorer. At the greater burial depth lateral movement towards the outlet was increased and initial emergence was earlier. Vertical movement was decreased because more fry were trapped within the gravel. At the higher density the alevins moved farther towards the inlet. The mean area occupied per alevin was unchanged by density and suggests competition within the gravel. The orientation of the alevins is discussed in relation to light and current. The results indicate that larger gravel is better than smaller gravel for the incubation of Pacific salmon. Burial depth seems unimportant, but should be great enough to prevent predation. The question of optimum density requires further study. Emergence patterns may apparently be modified through environmental control. / Science, Faculty of / Zoology, Department of / Graduate

The possible role of prolactin in the freshwater osmoregulation of laboratory reared juvenile chum (Oncorhynchus keta) and sockeye (0. nerka) salmon was investigated. Pituitary cytology indicated that prolactin cells of both species develop gradually during freshwater residence and downstream migration. During this time the prolactin cells increase slightly in size; the number of prolactin cell follicles also increases. Simultaneously, the intensity of cytoplasmic staining with erythrosin increases. Alternate day injections of 5 or 15 μg/g body wt prolactin (ovine) did not affect survival of chum fry in deionized water. Thirty micrograms per gram slightly increased survival while 60 μg/g decreased survival in deionized water. Prolactin injections prolonged, to a small extent, the survival of sockeye smolts in deionized water. Sockeye fry suffered only slight mortality after transfer from fresh water to deionized water. A prolactin dose of 5 μg/g did not alter this survival; however, doses of 15 μg/g or higher resulted in 40 to 70% mortality after 10 days in deionized water. Alternate day injections of 10 μg/g prolactin had no effect on plasma sodium concentrations of chum fry, sockeye fry, or sockeye smolts after transfer from sea water to either fresh water or deionized water. It is concluded, from histological and physiological evidence, that prolactin does not play an obvious role in the freshwater osmoregulation of juvenile chum and sockeye salmon. The possible role of prolactin in the spawning migration of adults is discussed. / Science, Faculty of / Zoology, Department of / Graduate

Estuarine residence and growth of juvenile chum salmon (Oncorhynchus keta) from Netarts Bay, Oregon were estimated from daily-formed growth increments of sagittal otoliths which are distinguishable from accretion patterns formed during freshwater residence. Estuarine residence time was inversely related to the average size at which juvenile chum salmon entered Netarts Bay. Among fin-clipped, hatchery fish, large individuals disappeared from Netarts Bay more rapidly than smaller members of the same release group during the first 9 days of estuarine residence. This selective removal was not evident among creek-reared chum which were smaller than the fin-clipped fish. Size-related emigration explains this variation in residence time. Growth rates were estimated from back-calculations of fork length from otoliths. The growth rates of juvenile chum salmon in Netarts Bay (0.6 mm FL/d; 3.5% bw/d) were lower than growth rates in other estuaries where harpacticoid copepods were a major prey item. Juvenile chum salmon that entered the estuary early in the spring grew faster than those which entered later in the year, possibly because of lower water temperature and lower density of small (50 mm FL) chum during the early period. High water temperature reduced apparent growth rates by slowing growth and causing emigration of larger, faster-growing individuals. / Graduation date: 1990

In this study, a number of experiments were undertaken to investigate possible methods for effective improvement of the texture and flavour of canned late-run chum salmon. These included removal of the skin and bones from the fish, processing of the boneless-skinless steaks in retort pouches, brine treatment using two washes with an 8% salt solution for one hour each time, and a precanning treatment in which the boneless-skinless steaks were soaked in a solution of 10% tripolyphosphate and 2% brine for two minutes. Only fish of advanced sexual maturity were used. The canned salmon was steam processed at 120°C for 65 minutes in an FMC laboratory retort. This was based on a known commercial process for 307 x 115 cans. Heat penetration studies were carried out to design the process schedules for the pouched samples. It was found that the pouched product required 48% less thermal processing time than the canned product to achieve similar lethality. Sensory results showed that the removal of the skin and bones did not produce any significant improvement in the flavour and acceptability of the fish. There was no significant difference between the polyphosphate/brine samples and the untreated (control) samples for all attributes tested. The brine treatment also did not improve the texture of the samples. However, there was less detection of late-run flavour in the brine treated samples when compared to the control. Comments offered by panelists described these samples as having a salty/briny flavour. Pouched samples had a firmer, drier and more fibrous texture than the canned product. They also scored better in terms of late-run flavour. Acceptance of the fish however was only moderate. As a consequence, although this study demonstrated an improvement in the texture and flavour of the pouched late-run chum in comparison to the canned product, it was concluded that a more acceptable pouched product could probably be obtained by using late-run salmon of less advanced sexual maturity. Results of linear regression analysis showed that significant relationships were obtained between sensory firmness, fibrousness and chewiness and instrumental hardness, maximum slope and chewiness. However, none of the sensory parameters were well predicted by the instrumental results. / Land and Food Systems, Faculty of / Graduate

Interactions between fish utilizing nearshore habitats of the Fraser River estuary were investigated by field observations and laboratory experiments. Chum salmon fry (Oncorhynchus keta) were the most abundant salmonid captured between April and June. Non-salmonid species captured included: threespine stickleback (Gasterosteus aculeatus), prickly sculpin (Coitus asper), and peamouth chub (Mylocheilus caurinus). Potential predators included: prickly sculpin, and northern squawfish (Ptychocheilus oregonensis), but few had been feeding on fish. Chum fry fed predominantly on surface insects but the proportion of benthic prey in the diet increased over time. Stickleback shared the greatest diet overlap with chum fry. Interactions between two dissimilar prey, chum fry and threespine stickleback, and a predator, cutthroat trout (Oncorhynchus clarki) were investigated in the laboratory. Prey response to hungry and satiated predators was related to the degree of risk. Although attack rates by trout on chum and stickleback were similar, trout captured more stickleback than chum, but consumed both prey at similar rates. I tested the hypotheses that prey foraging efficiency is reduced in the presence of a predator and increased in the presence of alternate prey. When alone, chum fed on surface Drosophila and mid-water Daphnia, while stickleback fed on benthic Tubifex and Daphnia. The feeding efficiency of chum increased in the presence of stickleback and decreased in the presence of trout. Hatchery and wild chum showed opposite dietary shifts in the presence of trout. Hatchery chum shifted from surface to mid-water feeding and the number of fish feeding significantly decreased. Wild chum fed at the surface, at significantly decreased feeding rates. In the presence of stickleback and trout the feeding behaviour of chum was similar to that when chum were alone. Stickleback feeding behaviour was not affected by presence of trout or chum. Chum and stickleback detected Daphnia faster than Drosophila or Tubifex, and chum responded to Daphnia significantly faster than stickleback. Foraging time per item was significantly less for chum than stickleback. Habitat use by fish prey was investigated in the presence and absence of trout and alternate prey. Wild chum shifted from mid-water to the surface in the presence of trout, but returned to mid-water when stickleback were present. Stickleback fed in bottom habitats regardless of the presence of trout or chum. When prey were confined to specific depths in the water column, trout attacked chum more frequently than stickleback in all locations and attacked both prey more frequently within 24 cm of the substrate. Movement by prey did not affect the attack rate. When given a choice between a food-rich open water habitat and a food-deficient vegetated habitat in the presence of trout and alternate prey, chum and stickleback used vegetated refugia significantly more in the presence of trout. Alternate prey presence decreased the proportion of chum but increased the proportion of stickleback using vegetation. Behavioural responses to avoid predation significantly reduced the foraging efficiency of prey. Chum showed stronger responses to trout than stickleback. The presence of stickleback reduced the effect of predation on foraging efficiency. Possible explanations for the positive effect of stickleback on chum feeding efficiency were experimentally examined including: social facilitation, reduced intraspecific competition, and the calming influence of stickleback on chum behaviour ("dither"). The results suggest that stickleback have a calming influence on chum behaviour and that mixed species feeding groups may reduce intraspecific competition. / Science, Faculty of / Zoology, Department of / Graduate