In young coho salmon (Oncorhynchus kisutch), UVR is known to elicit exposure avoidance behavior and suppress aggressiveness. The latter observation has been attributed to the indirect effect of fish seeking shade from solar UVR under rocks consequently losing sight of prospective rivals. The present study quantified the direct impacts of UVR on agonistic (Strikes, Chases, Approaches) and feeding behaviors in juvenile coho salmon by furnishing outdoor aquaria with structural elements (i.e., inverted funnels) that provided habitat complexity without generating shade during midday experimental trials. Frequencies and durations of behaviors were compared between conditions that excluded or included natural solar UVR. Results indicated that hostile pursuits (Chases) persisted significantly longer under UVR illumination. Likewise, the frequencies of more belligerent interactions (Strikes, Chases) tended to increase under UVR, while milder territorial assertions (Approaches) and foraging (Feeding Efforts) tended to decline. However, none of the latter four outcomes tested as significant.

Evidence suggests that the variability in recruitment of adult Pacific salmon is related to smolt survival during the first ocean year. Specifically, the first few weeks and first marine winter may be two critical periods of high mortality during early marine life. Mortality during early marine residency has been attributed to predation and size-dependent factors while high mortality during the first winter may be due to energy deficits and failure to reach a certain size by the end of the growing season. My study assessed factors influencing overwinter mortality and early marine growth in juvenile Chinook salmon (Oncorhynchus tshawytscha) from Marble River, Quatsino Sound, British Columbia. Juvenile salmon were collected during November 2005 and 2006 (fall) and March 2006 and 2007(winter). Mortality rates over the first winter derived from catch per unit effort across seasons ranged between 80-90% in all years. These are the first estimations of overwinter mortality in juvenile Pacific salmon. Fish size distributions showed no evidence of size-selective overwinter mortality between fall and winter fish in either 2005-2006 or 2006-2007. Otolith microstructure analyses showed no significant difference in circulus increment widths during the first four weeks after marine entry. Similarities in increment width indicated that early marine growth did not differ between fall and winter fish during early marine residency in 2006. These observations show that the high overwinter mortality rates of juvenile Chinook salmon in Quatsino Sound are not size-dependent. Total plankton biomass was significantly lower in the winter season but size distribution, gut fullness and energy density data did not show evidence of starvation. No correlation was found between early marine growth, size, energy accumulation and high mortality in Marble River juvenile Chinook salmon during their first ocean winter in Quatsino Sound. Possible factors influencing these high mortality rates may include non size-selective predation, disease, local environmental influences or an as yet unknown source. Future work should continue to focus on understanding the relationship between early marine survival and adult recruitment. The expansion of growth comparisons geographically and chronologically while determining the effects of predatory mortality on juvenile Chinook salmon along the north Pacific continental shelf and beyond are imperative to fully understanding this complex marine life stage. / Graduate

The reproductive cycle of Coregonus lavaretus (L. ) in Loch Lomond was investigated by monthly sampling. The stages of the cycle occurred at the same time each year and were precisely timed. The environment followed a regular pattern which varied seasonally and was repeated annually. Spawning synchrony within the population during the short breeding period may be in response to lunar phases. A qualitative echosounding survey was made. The spatial distribution of the fish is probably related to their feeding behaviour and was mainly pelagic in summer and benthic in winter. Diel vertical migrations were recorded at dawn and dusk and appeared to be related to negative solar altitudes. The fish occurred at the surface during the night and persisted with their diel vertical migrations when feeding behaviour was benthic. The regulation of the reproductive cycle in the common sole Solea solea was investigated. The timing of spawning is ultimately determined by sea temperature, and spawning synchrony within the population is probably achieved in the initiation of exogenous vitellogenesis by a unified response within the breeding population to a stimulatory photoperiod. In both Solea solea and Coregonus lavaretus, initiation of exogenous vitellogenesis occurred during a rapid rise in the condition of the fish. The photosensitivity of the reproductive system may possibly be linked to a threshold condition. The pineal organ of Coregonus lavaretus is typically salmonid and the convoluted epithelium contained photoreceptors, interstitial cells, and neurones. The interstitial cells gave rise to processes which extended into the perivascular space. Photoreceptor cells synapsed with neurones, photoreceptor cells (lateral processes) and possibly other cell types. The results suggest that the pineal organ functions as a photoreceptor.

The use of wrasse (Pisces: Labridae) as cleaner fish to combat infections with the parasitic copepods Lepeophtheirus salmonis (Kroyer) and Caligus elongatus (Nordmann) (sea-lice) in the culture of Salmo salar L. (Atlantic salmon) is now common. Infections with these parasites has caused considerable losses in the industry since its formative years. The use of the wrasse species Ctenolabrus rupestris (L. ) (goldsinny), Centrolabrus exoletus (L. ) (rockcook), Symphodus melops (= Crenilabrus melops) (L. ) (corkwing) and Labrus mixtus L. (cuckoo) as cleaner fish was first suggested in 1988. The use of these species in the industry is now widespread in Scotland, Ireland and Norway. The fish used are normally caught from the wild before being stocked with S. salar smolts during their first year at sea. The fish are routinely collected from waters close to the farm sites to be stocked. As most of the S. salar sea production sites in Scotland are located on the west coast of the country, the wrasse to be used in these sites are normally collected from these waters. The movement of wild fish into farm pens presents a risk of disease transfer from wrasse to S. salar and vice versa. Prior to their use as cleaner fish, these four species of wrasse had received little attention as subjects of scientific study. As a result, there was very little information available in the literature regarding their diseases. The present study was undertaken to investigate the potential pathogens present in wild populations in Scottish coastal waters, and, in particular, which of these pathogens, if any, could be transmitted to the S. salar. The study also investigated the susceptibility of wrasse to the two major viral diseases of S. salar to which they would be exposed in pens. In order to fully assess the pathogenicity of the potential disease agents under farm conditions, it was first necessary to establish the normal morphology of the wrasse species. Hence, a study of the morphological features of wrasse, with particular emphasis on those features important in the health of the fish was undertaken. Wrasse were shown to differ in many aspects from salmonids but shared many morphological features with other perciforme fish. Major differences from salmonids were evident in the skin, fins, pancreas, intestine, gonads and heart. There were also aspects of their morphology which differed from other perciforme fish, notably the structure of the heart. These features were regarded to be adaptations to the specific demands of their feeding strategies and habitats. This study was the first of its kind undertaken for wrasse and showed some early contraindications for the use of wrasse in culture; most notable was the marked lipid accumulation in, and resultant degeneration of, the liver resulting from the consumption of high energy S. salar feeds. Once the normal morphological features were established, it was possible to examine the disease status of wrasse. Wild fish were sampled from three different locations on the west coast of Scotland. These sites were all geographically distinct and were all used as sources of wrasse for the S. salar farming industry. Samples of wrasse were also obtained from farm sites supplied with wrasse from these wild sites, and an additional number of other geographically distinct farm locations. As a comparison wrasse were also obtained from a wrasse captive breeding facility and another captive location unrelated to the S. salar industry, a public aquarium. The fish from all of these sampling sites were examined fully for the presence of parasites, bacteria and, in some cases, viruses. Histological examination was also carried out on all of the fish studied. A total of 24 new parasite host records, and two tentative ones, were recorded from the four wrasse species studied. These new parasite records included protozoa, digeneans, nematodes and crustacea. Parasite infections were found to vary in prevalence, abundance and intensity in respect to the geographical characteristics of sampling sites and also the length of time spent in S. salar pens. It was concluded that the separation of wrasse from their natural diet and habitat influenced the degree of parasitism. None of the parasites found to infect wrasse were observed to cause any significant pathology in their hosts other than localised tissue responses. The possibility of transfer of wrasse parasites to S. salar was also investigated experimentally in a series of infections in which parasites dissected from wrasse were introduced to S. salar smolts by means of a novel gavage method. None of the parasites used established in the S. salar, indicating that there is little risk of transfaunation of parasites between wrasse and S. salar. However, this aspect requires further work due to the low number of parasites available and the subsequent low numbers of S. salar infected. Bacterial isolates were obtained from wrasse held in S. salar pens but were not found in any of the fish collected from the wild. Most of the bacterial strains isolated would normally be considered as opportunistic pathogens of fish. It was concluded that the relatively high levels of stress, both environmental and physical, that wrasse are subjected to under farm conditions were instrumental in the number of bacterial infections seen in wrasse. Only one pathogenic bacterial infection was seen in any of the fish sampled. This was an isolate of Aeromonas salmonicida, the agent known to cause the disease furunculosis, isolated from a wrasse obtained from one of the farm samples. Other authors have reported that this bacterium has already caused substantial losses of wrasse under farm conditions. It was concluded that Aeromonas salmonicida will prove to be a major pathogen of wrasse held in S. salar pens. No viruses wereI isolated from any of the wrasse studied. The susceptibility of wrasse to the most significant pathogens of S. salar under farm conditions was also subjected to investigation. In addition to sea-lice infection, the industry lists Infectious Pancreatic Necrosis (IPN) and Pancreas Disease (PD) as of primary importance for further research. Both of these diseases cause substantial losses in the industry. The susceptibility of wrasse to both of these disease conditions was investigated by means of experimental infections. In the case of IPN wrasse were infected by bathing with two different infective doses, a low dose which would be expected to induce the disease in S. salar parr and a second dose substantially higher than the first. The C. rupestris used were found to be susceptible to IPN. The wrasse developed some of the pathological characteristics typical of the disease in S. salar, however, other pathological signs were peculiar to wrasse. The recovery rate from the disease seen in wrasse was far more rapid than that recorded from S. salar. Shedding of the virus in the faeces of infected C. rupestris was also demonstrated. This study has illustrated for the first time the susceptibility of wrasse to IPN and that they can shed the virus in their faeces. This suggests that infected wrasse could be a source of continual reinfection in an affected sea site. Experimental infections of C. rupestris with PD followed a standard protocol for the reproduction of the disease in S. salar. Infection was by means of intraperitoneal injection with putatively infective material obtained from S. salar affected with PD. Two infection doses were used, the lowest dose used had been proven to be effective in inducing the disease in S. salar parr while the second dose, ten times higher than the first, had been shown to be effective in reproducing PD in S. salar smolts. The C. rupestris infected did not develop any of the typical signs of the disease seen in S. salar. It was, therefore, concluded that wrasse were not susceptible to PD.

Dietary proteins from Atlantic salmon and cod have previously been shown to have antidiabetic effects. Since dietary proteins are digested into small peptides before being absorbed through the intestinal mucosa, it is reasonable to deduce that the antidiabetic effect is due to enzymatically-digested peptides rather than the proteins themselves. The aim of this study was to develop a protocol to recover peptides with antidiabetic effects from salmon and cod protein digests and then scale up and optimize the salmon protein hydrolysate production process for industrial-scale production. The peptide mixtures were screened using cell culture assays for insulin-modulating activities and were further fractionated and purified for the final identification. Total yields of salmon and cod protein hydrolysates (<1 kDa) as measured by Kjeldahl nitrogen were 16.9% and 40.1%, respectively. The production process used for the salmon protein hydrolysate (<1 kDa) showed good reproducibility and potential for the industrial-scale production.

Graduation date: 1953

Growth retardation in King salmon Oncorhynchus tshawytscha (Walbaum) is a common and significant problem affecting marine farming operations in New Zealand. While the basic marine culture requirements for the King salmon species are well understood, the etiology of seawater adaptation and growth retardation remains understudied. Consequently, this study was established to investigate the physiological state and causative factors of growth retardation in collaboration with a leading New Zealand aquaculture company, New Zealand King Salmon Ltd (NZKS). Hypoosmoregulatory indicators are not currently used by marine farmers in New Zealand due to the belief that King salmon are more adaptable to seawater than their more highly cultured counterparts, Coho and Atlantic, and can be transferred to seawater anytime after a critical weight is achieved. This study sought to investigate changes in hypoosmoregulatory ability and its relation to water temperatures commonly used in the hatchery environment. This was determined by changes in the activity of the predominating seawater-adapting gill enzyme Na+/K+-ATPase, as an indirect measure of its abundance during smoltification. Changes in plasma ion profiles and the ability to regulate ions after abrupt transfer were also measured and compared with enzymatic activity throughout the austral springtime smoltification period in commercial strains of under-yearling King salmon. It was found that King salmon do undergo a distinct austral spring-time temporal increase in hypoosmoregulatory processes. This was characterised by a 2-fold increase Na+/K+-ATPase activity which was concomitant with reduced plasma Na+ in freshwater and following a seawater challenge in fish between fork lengths of 140-160 mm. Despite no consistent reduction in Na±/K+-ATPase activity during desmoltification, it was shown that the percent of ATP dependent activity specific to Na+/K+-ATPase diminished over time. Increased residual ATP dependent activity is hypothesised to be a result of apical H+-VATPase activity as a compensatory mechanism to rapidly normalise plasma Na+ during desmoltification concomitant with elevated basolateral Na+/K+-ATPase. Water temperature has been linked with the advancement and shortening of the smoltification period in several species. Gill Na+/K+-ATPase activity and hypoosmoregulatory ability in King salmon were negatively affected by increasing water temperatures above 12°C in contrast to a constant 12°C. The level of growth retardation was dependent on the time of transfer to seawater and was found to increase during a period of reducing hypoosmoregulatory ability. The transfer of growth retarded King salmon back to freshwater resulted in a complete reversal of the growth retarded state, comparable to that observed in Coho and Atlantic salmon. Growth retarded fish were able to readapt back to freshwater with higher survival and growth rates compared to the transfer of normal growing sub-adult King salmon, strongly demonstrating that growth retarded fish are more adapted to freshwater. Osmoregulatory physiology, and endocrinology during the transfer of growth retarded and normal growing fish were investigated. Overall, these results have fundamental implications for the aquaculture of King salmon that are able to be applied by industry to improve current husbandry practices.

The role and functions of Urotensin II (UII), Urotensin II-related peptide (URP) and proangiotensin-12 (PA12) are currently ambiguous, either due their relatively new identification and isolation from their host species, or due to contrasting and conflicting reports observing the physiological and pathophysiological role of these spasmogens within the mammalian cardiovascular system. Accordingly, we sought to determine the true physiological functions of these peptides in both healthy and diseased states. The initial task was to reveal potential reasons for the contrasting responses to UII, and to define the role of UII within the isolated rat heart. UII and URP retain a highly conserved cyclic region, shown to be necessary in receptor binding and activation, with the high inter-species variance within the N-terminus reported to be of little importance. Our research revealed UII to be highly species-specific, stimulating potent, sustained vasodilation of the coronary arteries in response to the native form infused, while non-native UII peptides had either no effect, or caused significant vasoconstriction. UII-induced vasodilative effects were found to be mediated by nitric oxide and prostaglandin activity combined. Reviewing publications to date it was evident that many studies employed UII foreign to the host species, reporting potentially untrue effects, based on our findings. Recent studies have identified UII as a potent agent in developing and promoting atherosclerosis and coronary artery disease through UII-induced mitogenic activity and promoting foam cell formation. Hence, we observed the effect of infusing the native species of UII and URP into a model of cardiac ischemia-reperfusion. Both preconditioning the heart with UII or URP, or infusing UII or URP upon reperfusion caused significant coronary vasodilation following ischemia, and significantly attenuated ischemic-induced myocardial injury. These studies indicated elevating UII and URP provided a level of cardioprotection, not only when administered into healthy hearts prior to an ischemic event, but also in hearts having already undergone ischemia and the resultant endothelial damage. PA12 was the third peptide tested in the current thesis. Being newly identified and suggested to be a new component of the renin-angiotensin system (RAS) it was important to define the physiological role of PA12 upon the cardiovasculature, as the RAS is heavily associated with the development and progression of cardiovascular disease. Utilising the Langendorff isolated rat heart technique, PA12 was found to cause potent vasoconstriction of the coronary arteries, mediated by the angiotensin II type 1 receptor (AT₁R). Furthermore, using subjecting the perfusate samples to radioimmunoassay and RP-HPLC revealed PA12 was converted to AngII. Both PA12-induced vasoconstriction and generation of AngII were found to be dependent upon chymase activity, with inhibition of ACE1 having little effect. Myography was employed to further study the vascular response to PA12 throughout the rat arterial system from the common carotid to the femoral arteries. PA12-induced vasoconstriction displayed a potency gradient, with greatest constriction observed in vessels closest to the heart, with potency reduced and eventually lost further from the heart. PA12-induced vasoactivity was shown to be dependent upon both chymase and ACE1 activity, with ACE1 regulating PA12 activity with greater potency. The intracellular pathways stimulated in response to PA12 were defined using western blotting, with PA12 stimulating phosphorylation of ERK1/2, JNK, p38 and PKCα/β₁₁, but having no influence on PKCδ/θ. Stimulation of these pathways is consistent with the observed PA12-induced vasoconstriction, and also indicates that PA12 activation of AT₁R and the subsequent cytokines, could potentially stimulate hypertrophy, apoptosis, cell growth and differentiation, and inflammation, promoting cadiovascular remodelling and progressing atherosclerosis, hypertension and other vascular diseases if not sufficiently regulated. Taken together, these studies indicate PA12 may have a primary role within the local, tissue-based RAS, providing an alternate substrate to angiotensin I, while ACE1 is the primary regulatory enzyme within the circulation. Our findings also display the chymase-dependent PA12/AT₁R pathway as potential novel targets for pharmacological inhibition of RAS activity to ameliorate hypertension and maladaptive vascular remodelling.

Thesis (Ph. D.)--University of Wyoming, 2006. / Title from PDF title page (viewed on April 15, 2008). Includes bibliographical references.

Diss. (sammanfattning) Umeå : Sveriges lantbruksuniv. / Härtill 3 uppsatser.