With the hope of being able to demonstrate the relative effect of predator species on the young sockeye (Oncorhynchus nerka) in different lakes, the Skeena river investigation instituted a program of standard gill-netting in 1945. Study of the catches and information obtained from netting experiments indicated that the catch per net-night was the best estimation of the concentration of each preying species in different areas. Coupling this catch per net-night with the average volume of sockeye found in the stomachs of predators caught, a measure of predation called the "predation index" was calculated. On the basis of this index, the populations of nine lakes of the Skeena drainage were classified as either high, low or intermediate in effect on young sockeye. / Science, Faculty of / Zoology, Department of / Graduate

This thesis has been designed to examine the share system and to study its effects on innovation, employment and income in the British Columbia salmon fishing industry. The approach taken has been that of examining the theoretical basis of the share system and then noting how the system has worked in practice. The share system has demonstrated some notable advantages over a wage system in its approach in providing an incentive for hard work and in the economizing of materials used, Against these advantages must be weighed the heavy burden of risk which is shifted from the capitalist to labour. Share fishermen are not assured that they will earn any income from a particular fishing trip and may, in fact, be forced to bear part of the losses of those ventures which fail. The share system creates a rigidity in the free movement of resources within the fishing industry by requiring that the net proceeds from fishing be divided between the crew and the vessel owner in fixed proportions. The allocation to labour of a fixed percentage of all net income results in the entrepreneur requiring a higher rate of return on his investment than would be the case if he were operating in a freely competitive market, thus in theory the share system would inhibit innovation,, The entrepreneur requires that his investment projects have a sufficient return to repay both his capital and interest after paying a share to labour. The number of licensed fishermen and fishing boats has increased annually since 1951. The opportunity of obtaining a high income which is a feature of the share system is a particular incentive which attracts new recruits into the industry. However, many fishermen fail to remain in the industry due to the low and unstable earnings they experience. The incomes of British Columbia salmon seine fishermen appear, on the average, to be below those offered in alternative occupations, though there are certainly some very high incomes earned by a few fishermen0 The increased employment both of labour and capital can, in the main part, be blamed on the common property feature of sea fisheries. The share system, though playing a part in the total industry, is not the most important variable, A solution to the difficulties that the industry faces can best be sought by changes and adjustments elsewhere. / Arts, Faculty of / Vancouver School of Economics / Graduate

This study was undertaken to try to delay gonadal maturation of pink salmon for one year beyond their normal two year life cycle. This would allow these fish to spawn in years of low or nonexistent escapement and possibly increase these "poor" year populations. Three experiments were conducted to investigate the efficacy of the antigonadotropic drug, methallibure, in inhibiting gonadal maturation in pink salmon. Gonadosomatic index, oocyte diameter, and stages of cell maturation in the testis and oocyte maturation in the ovary were measured. The first or pilot experiment involved a range of doses of methallibure (0.10 mg., 0.32 mg., and 1.0 mg./gm./2wks.) to determine the optimal dose for subsequent experiments. All doses had only a slight slowing effect on maturation. This result and possible undesirable effects of higher doses prompted the decision to use the 0.10 mg./gm. dose for subsequent experiments. The second or long-term experiment investigated the effects of methallibure and a constant 12 hours light:12 hours dark photoperiod on gonadal maturation of males and females for a period of ten months. Methallibure completely inhibited testicular maturation by preventing the transformation of primary into secondary spermatogonia. Ovarian maturation, however, was only slowed. The treated ovaries possessed oocytes in the oil globule stage while control ovaries had oocytes in the secondary yolk globule stage. Methallibure had an antithyroidal effect under natural photoperiod but not under constant 12L:12D photoperiod or at a high dose (1.0 mg./gm). Stress from kidney disease may have been operative in this effect. Methallibure also slowed the rate of increase in body weight. The constant 12L:12D photoperiod slowed gonadal maturation in both males and females. It is suggested that a specific day-length and an endogenous rhythm stimulate the initiation, maintenance, and termination of gonadal maturation and that the seasonal daylength fluctuations function as a synchronizer. The difference in effect of methallibure on males and females may be due to treatment beginning prior to the start of testicular maturation but after the start of vitellogenesis. To investigate this possibility, methallibure treatment was begun at successive intervals prior to the start of vitellogenesis in the third or sequential experiment. This treatment had no effect on ovarian maturation which suggests that the females are less sensitive to methallibure than are the males. Treatment with a higher dose started early in juvenile life may inhibit ovarian maturation. From this study, only the males could be delayed and, therefore, possibly spawn in "poor" years. However, Funk and Donaldson (1972) were able to achieve the same goal by maturing males in the year of hatching, thus making a three year program impractical. The value of a long program would be the delay of ovarian maturation since Funk et al. (1973) were unable to advance maturation of females by one year. / Science, Faculty of / Zoology, Department of / Graduate

Studies were conducted to determine the onto genetic changes in the number and relative concentration of the electrophoretically distinguishable hemoglobin polymorphs of coho salmon, Oncorhynchus kisutoh and the influence of certain environmental factors upon the expression of the hemoglobin variants. In addition some of the oxygen equilibrium characteristics of the hemoglobin of freshwater fry and adult coho were investigated using both hemolyzates and whole blood. Throughout the life cycle of coho salmon seventeen to nineteen distinct hemoglobin components were identified in micro-starch-gel electropherograms prepared in borate buffer at pH 8.5. These components formed three main electrophoretic hemoglobin patterns associated with different stages of the life cycle. Unhatched embryos and alevins possessed twelve anodic and one cathodic components. All except three anodic components had disappeared from the blood of free-swimming fry fourteen weeks after hatching. This three-component pattern was retained until the beginning of the presmolt period, approximately eleven months after hatching. At this stage, five new cathodic components, one new anodic component and one anodic component which had previously been visible in alevin electropherograms appeared. In presmolts and smolts these additional seven components accounted for less than 20 % of the total hemoglobin of the blood while the three components observed in fry blood accounted for the remainder. Following migration to sea water the relative concentration of these seven components gradually increased to 45 to 50% of the hemoglobin over a two-month period. No further change in either the number or relative concentrations of the hemoglobin components was observed during the remaining phases of the life cycle. Since it was apparent that changes in hemoglobin pattern were temporally associated with changes in the characteristics of the environment occupied by the juvenile coho the effects of water temperature, dissolved oxygen concentration and salinity upon the physical development and electro-phoretic hemoglobin pattern of underyearling coho were examined. Exposure to freshwater temperatures of 1.4 to 15.0 C, dissolved oxygen concentrations of 2.2 to 9.7 ppm and salinities of 0 to 30 °/oo for periods of 49 to 60 days had no influence upon the electrophoretic hemoglobin pattern of either 3 1/2-month-old fry or 11-month-old presmolts. Presmolts reared for 60 days in freshwater at 15 C and in 10 °/oo salinity at 9.2 C grew at a highly accelerated rate and were equal or greater in size than 16 1/2-month-old postsmolts which had been residing in sea water for one month. These large presmolts retained the hemoglobin pattern characteristic of normal presmolts of the same age. Postsmolts maintained in aerated freshwater rather than sea water underwent changes in the electrophoretic hemoglobin pattern characteristic of sea-water residents. The foregoing observations suggest that age rather than physical size or environmental factors is the main determinant in the expression of the polymorphic hemoglobins of coho salmon. The oxygen equilibrium characteristics of adult coho hemoglobin and hemoglobin components A6-8 (fry hemoglobin) isolated from adult hemolyzates by ion-exchange chromatography were investigated. Adenosine triphosphate concentrations ranging from 0.0 to 0.76 moles/mole hemoglobin had no influence upon the oxygen equilibrium of adult hemolyzates whereas at a concentration of 7.56 moles/mole P₅₀ increased by 1 to 2 mm Hg. Since erythrocyte ATP concentrations of freshwater adult coho ranged between 0.8 and 1.3 moles/mole hemoglobin this organic phosphate is probably not a modifier of oxygen affinity in coho salmon. The hemoglobin of adult coho was relatively insensitive to variations in pH and temperature with ∅ =-0.172 at 9.8 C over the pH range of 6.95 to 8.20 and Δ log P₅₀ = 0.019 between 5 and 15 C. The Bohr effect of fry hemoglobin was nonlinear so that ∅ = -0.033, -1.729 and -0.182 in the pH ranges of 6.82 to 7.08, 7.08 to 7.50 and 7.50 to 8.50, respectively. The estimate of Δ log P₅₀ was 0.056 for fry hemoglobin. Thus at 9.8 C the oxygen affinity of fry hemoglobin exceeded that of adult hemoglobin at pH greater than 7.3 but was lower at values of pH less than 7.3. At pH 7.4, the P₅₀ of fry and adult coho hemoglobin was 8.4 and 17.9, respectively. In neither case was a Root effect observed. Heme-heme interaction was similar for both adult and fry hemoglobin and the value of n always exceeded 1.0. The estimate of n was generally less than 2.0 at pH greater than 7.0 and tended to decrease as the pH or the equilibration temperature increased. Studies with fry and adult whole blood equilibrated With 0.2 and 3.4 mm Hg of carbon dioxide generally confirmed the qualitative differences observed between the oxygen equilibria of fry and adult hemolyzates. The estimates of P₅₀ at 9.3 C and PCO₂ of 0.2 and 3.4 mm Hg were 5.5 and 12.5 mm Hg respectively for fry blood and 10.7 and 15.6 mm Hg, respectively, for the blood of freshwater adults. / Science, Faculty of / Zoology, Department of / Graduate

Juvenile, pre-smolt coho salmon were subjected to a decrease in environmental temperature from 12°C (temperature of acclimation) to 2°C over a period of approximately 72 hours. During this time, plasma Cortisol values were estimated by the competitive protein binding (CPB) technique. In addition, an histometric analysis of the interrenal tissues of these fishes was performed as a measure of interregnal activity. Experimental results indicated that fluctuations in plasma Cortisol concentrations occurred within 120 hours of the initiation of temperature alteration. Control levels for plasma Cortisol were 2.9 ± 0.75 ug cortiso1/100 ml plasma (mean ±S.D.). Maximum plasma Cortisol concentration, observed at hour 84 after temperature alteration, was 27.0 ± 2.8 ug cortisol/100 ml plasma (mean ± S.E.). By hour 96 experimental cortisol values returned to a level just slightly above those of controls and did not change significantly after that time. Measurements of interrenal nuclear diameters showed a significant increase in interrenal activity 14 days after initiation of exposure to cold. This level of interrenal activity was maintained until the experiment was terminated (20 days exposure to cold). It is concluded from this study that during acclimation to cold temperature, plasma cortisol values of juvenile, pre-smolt coho salmon demonstrate an early and rapid increase (within 120 hours exposure to colder temperature) followed by an equally rapid decrease to a level just slightly above that of controls. Furthermore, it is concluded that juvenile, pre-smolt coho salmon treated in this manner show no histologically demonstrable increase in interrenal activity until well after plasma cortisol values have become stabilized at a level slightly above that of controls (14 days exposure to cold). / Science, Faculty of / Zoology, Department of / Graduate

Some of the kinetic characteristics of the sodium and potassium-activated adenosine triphosphatase of the fragmented cell membranes of cells from the gills of sea water adapted coho salmon Oncorhynchus kisutch, and changes in this enzyme upon exposure to sea water and during the fry to smolt stages of fresh water reared juvenile coho were investigated. Inhibition with 4 X 10⁻⁴ moles/liter ouabain was used to assay the activity of this enzyme since this ATPase is specifically inhibited by ouabain (Skou, 1957). The following assay conditions were found to result in maximal hydrolysis of ATP in enzyme preparations from sea water adapted coho: pH, 7.4; incubation temperature, 40°C; NaCl and KCl concentrations of 100.0 and 20.0 mmoles/liter, respectively, and Mg²⁺ -ATP, 5.0 mmoles/liter. The Km for ATP was 0.2 mmoles/liter. The enzyme activity recorded with magnesium ions as the only cation present (Mg²⁺-ATPase) was not affected by any concentration of ouabain, although the addition of sodium ions (100 mmoles/liter) appeared to inhibit this activity slightly. The additional hydrolysis of ATP observed when sodium, potassium and magnesium ions were present was inhibited by ouabain. The Ki for ouabain was; 7 X 10⁻⁶ moles/liter when sodium and potassium ion concentrations were 100.0 and 20.0 mmoles liter, respectively. The (Na⁺ + K⁺)- activated ATPase of sea water adapted coho was characterized by its high ouabain-sensitive activity and the large activating effect of potassium ions in the presence of magnesium and sodium ions compared to the activity observed with the latter two ions alone. This enzyme in preparations from the gills of fresh water reared fish was characterized by a high activating effect of sodium ions when present with magnesium ions. This sodium activation often comprised over 60% of the total ouabain-sensitive activity. Considerable increases in the total activity, and activating effects of potassium ions and decreases in the activating effects of sodium ions alone were observed when fresh water reared coho were transferred directly to sea water. The changes in the activating effect of the ions were noticable after 5 days exposure to sea water although no changes in the total activity of the enzyme occurred until after 10 days exposure. On a seasonal basis changes in enzyme activity occurred which were apparently linked to the stage of development of the parr-smolt transformation in fresh water reared juvenile coho. Activities during the period of October 1, 1968 to late November, 1968 were generally quite low. A sharp peak in activity occurred in December, 1968 to late January, 1969 which decreased to a low level by mid-February. Up to and including this last period the activity of enzymes from the gills of both fresh water and sea water reared coho were qualitatively similar although the seawater fish always had a higher enzyme activity. During the period of mid-February to late April,1969 the enzyme from fresh water reared coho changed in total activity and characteristics of sodium activation and potassium activation and became very similar to that of sea water reared fish of the same age. / Science, Faculty of / Zoology, Department of / Graduate

Exploitation of Skeena River sockeye salmon (Oncorhynchus nerka) has been conducted almost solely by drift gillnets since inception of the commercial fishery in 1877. Selective action of gillnets is a factor which may have contributed to a long term decline in sockeye production and to other features of the population biology. This study was designed to determine the selective properties of nylon gillnets presently in use; to compare these with properties of linen nets used prior to 1955; to adjust age composition estimates of escapement levels prior to 1946; and to re-examine brood year production. In addition, the selective action was examined of the fishery as a whole on sockeye and pink salmon (O. gorbuscha) in 1968. The selective properties of six nylon gillnets ranging in mesh size between 4-5/8 inches and 5-5/8 inches, which corresponded with sizes normally used in the commercial fishery, were to be determined through a simultaneous fishing experiment, and selectivity curves were computed by Holt's (1963) normal probability technique. Unique selectivity curves for each mesh size could not be determined from the sockeye data. Mean size of age class l.2 sockeye (representing about 12 per cent of the sample) increased with mesh size but mean size of age class 1.3 sockeye (representing about 82 per cent of the sample) demonstrated no trend. Age class 1.3 sockeye were among the largest on record and it was postulated that fish of this age class were too large to gill properly in all mesh sizes used. A comparison of the predominant mesh of nylon gillnet (5-1/4 inch) with linen nets of the mesh used in the historic fishery (5-5/8 inch) was also influenced by the large size of age class 1.3 sockeye. Nylon nets were 2.5 and 2.7 times as efficient as linen for sockeye, and 8.0 and 9.0 times as effective for pink salmon. Nylon gillnets, although smaller, caught larger sockeye and pink salmon than did the linen gillnets. Variances about mean size of sockeye and pink salmon were also greater for catches in nylon as opposed to linen gillnets. In total, the selective properties of the commercial fishery reflected the results obtained in the nylon gillnet multi-mesh experiment. An overall selectivity curve computed for sockeye salmon by the direct method of Regier and Robson (1966) approximated a skew-normal distribution. Examination of the age-sex class components of the stock indicated that selection increased linearly over the length range of age 1.2 sockeye of both sexes, and decreased linearly over the length range of age class 1.3 sockeye. A selectivity curve was also computed for pink salmon and this curve, in total, also assumed a normal shape in spite of the extremely small size of pink salmon in 1968. The length-girth relationships of the two species were shown to differ and this accounted for most of the difference between the selectivity curves. The relationship between maximum efficiency and the maximum girth to perimeter mesh measure closely approximated the value of 1.2: 1.0 reported by McCombie and Berst (1969) for other species. Retention by gillnets declined once the girth/mesh ratio exceeded 1.2 for sockeye. For pink salmon, no females were of a size to equal this ratio; the descending limb of the selectivity curve was due solely to males as the retention rates declined once girth/mesh ratio exceeded 1.0. These findings suggest that in most years the gillnet fishery on the Skeena River would tend to select relatively larger sockeye salmon. In years such as 1968, however, selection would be against smaller fish. This frequent reversal combined with the intense modern fishery, which tends to remove virtually all fish during a short period and allows almost complete escapement in periods between fishing, suggested that selective fishing has probably not been a significant factor in decreased production. / Science, Faculty of / Zoology, Department of / Graduate

Studies of Saprolegnia infections of fish in British Columbia were made to determine disease causing agents and infection conditions. Saprolegnia diclina Humphrey was the most frequently observed parasite. This fungus reproduced sexually both on fish tissue and hemp seed cultures. No definite isolations of S. parasitica Coker were made although some non-sexually reproducing isolates of a Saprolegnia sp. were found. The validity of the species, S. parasitica, has been examined and questioned on the basis of present identification characteristics. Infection studies using S. diclina as the parasite and fingerling coho (Oncorhynchus kisutch) as the host indicated a distinct correlation between temperature and infection. At normal cool temperatures, e.g., 8° C, no infection occurred; at 9°C or above, some infection resulted. Above 9° C, the rate of infection increased as temperature increased. Temperature was also associated with the time at which infection occurred after inoculation. At 18°C, infection began earlier than at 13 C, Heat-shock treatment tended to reduce the temperature-time effect causing initial infection at 13°and at 18° C to occur almost simultaneously. Cold-shock treatment resulted in some infection. Such treatment, however, did not produce the same immediate infection as heat-shock. Histological studies demonstrated the infection to be concentrated in the host epidermis with fungal hyphae at sites of heaviest infection extending through the dermis and into underlying muscle tissues. / Science, Faculty of / Botany, Department of / Graduate

The neurohypophysial hormones of Pacific chinook salmon (Oncorhynchus tschawytscha) were purified and the amino acid sequence of both hormones determined. The extraction and purification procedure was developed in an effort to maximize the yields of pure hormones. Pituitary glands were extracted at 4°C using 0.2 M acetic acid. Purification consisted of gel filtration, ultrafiltration, and ion exchange. Gel filtration on Sephadex G-15 columns was used to separate neurohypophysial peptides from high molecular weight material. Separation of the two hormones was accomplished on one of three cation exchangers: carboxymethylcellulose, phosphocellulose or sulfoethyl-Sephadex. The hormones were eluted from cation exchange columns using a sodium or ammonium ion concentration gradient at constant pH; pH 5 was used for chromatography on carboxymethylcellulose and on phosphocellulose; pH 2.45 was used for chromatography on sulfoethyl-Sephadex. The two hormones were purified further by rechromatography of individual hormones on another cation exchange medium. The material obtained by rechromatography was pure as determined by amino acid analyses. The yields of pure hormones at the end of purification procedure was 48% of the starting material. The specific activities of the two purified hormones were 145 and 229 oxytocic units per milligram for Hormone I and Hormone II respectively. The amino acid sequence of Hormone I was determined by a combination of three methods: subtractive Edman degradation, partial acid hydrolysis, and Dansyl-Edman technique. The amino acid sequence of Hormone I was found to be that of 4-serine, 8-isoleucine oxytocin. The amino acid sequence of Hormone II was determined by the Edman subtractive method, the Dansyl-Edman technique, and the mobility of the C-terminal residue on high voltage electrophoresis. The amino acid sequence of Hormone II was found to be that of 8-arginine oxytocin. The two neurohypophysial hormones described from salmon have amino acid sequences identical with those described from four species of Gadiformes and one species of Cypriniformes by other workers. The position of Salmoniformes on the evolutionary tree of teleost fishes suggests that these structures are characteristic of a wide range of teleosts. / Science, Faculty of / Zoology, Department of / Graduate

Supervisor: N. R. Liley The endogenous and exogenous factors contributing to a diel rhythm of locomotor activity in juvenile sockeye salmon Oncorhynchus nerka (Walbaum) were examined in the laboratory. The basic measure employed in the investigation was spontaneous locomotor activity. High frequency sound (800 kHz) was used as a monitoring technique to collect continuous activity records. Three major areas received attention. First, a description and analysis were provided for the entrained diel activity pattern under three different temperatures (5°, 10°, and 15°C) and three different photoperiods (8L 16D, 12L 12D, and 16L 8D). The combined effects of temperature and photoperiod upon the basic 24 hour response were recorded and analyzed. Juvenile sockeye salmon were nocturnally active immediately after emergence from the gravel. A diurnal activity pattern was gradually acquired during the following 14 days and was maintained for 12 months. Photoperiod was the primary environmental synchronizer for either diurnal or nocturnal activity. The endogenous component of the activity rhythm was examined in constant environmental conditions. Constant light (34.4 lux at 10°C) facilitated the free-running response while constant dark inhibited it. The spontaneous frequency in constant light was 23.30 hours but this could be altered by light intensity or periodic feeding. The final experiments focused upon the relationship between the environmental stimulus (photoperiod) and the physiological sensory mechanisms mediating the entrained response. The eyes were the primary photoreceptors mediating information about the light-dark environment. The entrained activity response disappeared when the retina was not illuminated. When the pineal body was removed or shaded, juvenile sockeye responded with increased activity. Intraperitoneal injections of melatonin (N-acetyl-5-hydroxy-tryptamine) or serotonin (5-hydroxy-tryptamine) selectively altered the activity amplitude in either the light or dark respectively. Juvenile sockeye salmon possess an endogenous circadian activity rhythm which is synchronized by the photoperiodic cycle. The fish are generally light active, except for the period immediately after emergence. However, interactions between daylength and temperature can result in temporary dark active responses. Mediation of the photoperiodic information occurs via the retina, but without transmission by optic nerve pathways. Chemical agents (melatonin and serotonin) produced by the retina and/or pineal might control the activity amplitude in light and dark, thus resulting in the characteristic entrained pattern. / Science, Faculty of / Zoology, Department of / Graduate