Reproduction is a critical period of salmonid fish life history. As early life stages are particularly sensitive to biotic and abiotic constraints, studying these stages in terms of survival is essential in salmonid population ecology, stocks management, conservation and restoration. No characterization of salmonids spawning habitats on scientific basis has been made to date in Eastern Baltic region, which rivers are important for salmonid reproduction and significantly contribute to the sea trout and salmon stocks in the Baltic. The aim of this work was to assess sea trout spawning sites characteristics and to estimate its effects on reproductive success in a typical lowland salmonid stream – Blendžiava. The spawning site selection by sea trout females and characteristics of spawning sites at different spatial scales were determined, spawning nests sedimentary, hydraulic, and water physico-chemical characteristics were assessed. To test how the spawning site selection influence reproductive success, in situ experiment on survival of sea trout eggs, study on fry emergence from natural redds and on dispersal of juveniles after emergence were accomplished. Additionally, the study on reproductive interaction between sympatric lampreys and salmonids was conducted. Study results revealed, that sea trout has specific spawning site preferences at the stream-, reach- and microhabitat scale, and are related with optimal conditions for egg survival. Vertical hydraulic gradient of... [to full text] / Reprodukcija yra kritinis lašišinių žuvų gyvenimo momentas. Kadangi ankstyvosios vystymosi stadijos yra ypač jautrios biotiniams ir abiotiniams veiksniams, šių stadijų tyrimai yra esminiai lašišinių žuvų populiacijos ekologijai, valdant, apsaugant ir atstatant išteklius. Tačiau mokslinių lašišinių žuvų reprodukcijos tyrimų iki šiol nebuvo atlikta Rytų Baltijos regione, kurio upės yra svarbios lašišinių žuvų reprodukcijai ir jų ištekliams Baltijos jūroje. Šio darbo tikslas buvo nustatyti šlakių neršto vietos pasirinkimo dėsningumus, naudojamų nerštaviečių charakteristikas ir įvertinti jų įtaką reprodukcijos efektyvumui tipiškoje lašišinėje lygumų upėje Vakarų Lietuvoje Blendžiavoje. Darbe buvo vertintas šlakių neršto vietų pasirinkimas ir charakteristikos skirtingo erdvinio mastelio buveinėse, nustatytos neršto lizdų substrato, hidraulinės ir porinio vandens fizikocheminės charakteristikos. Kad nustatyti, kaip lizdų charakteristikos įtakoja reprodukcijos efektyvumą, buvo atlikti šlakių ikrų inkubacijos in situ eksperimentai, mailiaus ritimosi iš natūralių lizdų ir pasklidimo iš nerštaviečių po upelį tyrimai. Taip pat buvo atlikta speciali studija, kad įvertinti lašišinių žuvų ir nėgių reprodukcinę sąveiką simpatrinėmis sąlygomis. Tyrimų rezultatai parodė, kad šlakiai turi specifinius reikalavimus neršto vietai upelio, vagos geomorfologijos ir mikrobuveinės mastu, ir yra susiję su optimaliomis palikuonių išgyvenimo sąlygomis. Vertikalusis hidraulinis gradientas buvo esminis... [toliau žr. visą tekstą]

Reprodukcija yra kritinis lašišinių žuvų gyvenimo momentas. Kadangi ankstyvosios vystymosi stadijos yra ypač jautrios biotiniams ir abiotiniams veiksniams, šių stadijų tyrimai yra esminiai lašišinių žuvų populiacijos ekologijai, valdant, apsaugant ir atstatant išteklius. Tačiau mokslinių lašišinių žuvų reprodukcijos tyrimų iki šiol nebuvo atlikta Rytų Baltijos regione, kurio upės yra svarbios lašišinių žuvų reprodukcijai ir jų ištekliams Baltijos jūroje. Šio darbo tikslas buvo nustatyti šlakių neršto vietos pasirinkimo dėsningumus, naudojamų nerštaviečių charakteristikas ir įvertinti jų įtaką reprodukcijos efektyvumui tipiškoje lašišinėje lygumų upėje Vakarų Lietuvoje Blendžiavoje. Darbe buvo vertintas šlakių neršto vietų pasirinkimas ir charakteristikos skirtingo erdvinio mastelio buveinėse, nustatytos neršto lizdų substrato, hidraulinės ir porinio vandens fizikocheminės charakteristikos. Kad nustatyti, kaip lizdų charakteristikos įtakoja reprodukcijos efektyvumą, buvo atlikti šlakių ikrų inkubacijos in situ eksperimentai, mailiaus ritimosi iš natūralių lizdų ir pasklidimo iš nerštaviečių po upelį tyrimai. Taip pat buvo atlikta speciali studija, kad įvertinti lašišinių žuvų ir nėgių reprodukcinę sąveiką simpatrinėmis sąlygomis. Tyrimų rezultatai parodė, kad šlakiai turi specifinius reikalavimus neršto vietai upelio, vagos geomorfologijos ir mikrobuveinės mastu, ir yra susiję su optimaliomis palikuonių išgyvenimo sąlygomis. Vertikalusis hidraulinis gradientas buvo esminis... [toliau žr. visą tekstą] / Reproduction is a critical period of salmonid fish life history. As early life stages are particularly sensitive to biotic and abiotic constraints, studying these stages in terms of survival is essential in salmonid population ecology, stocks management, conservation and restoration. No characterization of salmonids spawning habitats on scientific basis has been made to date in Eastern Baltic region, which rivers are important for salmonid reproduction and significantly contribute to the sea trout and salmon stocks in the Baltic. The aim of this work was to assess sea trout spawning sites characteristics and to estimate its effects on reproductive success in a typical lowland salmonid stream – Blendžiava. The spawning site selection by sea trout females and characteristics of spawning sites at different spatial scales were determined, spawning nests sedimentary, hydraulic, and water physico-chemical characteristics were assessed. To test how the spawning site selection influence reproductive success, in situ experiment on survival of sea trout eggs, study on fry emergence from natural redds and on dispersal of juveniles after emergence were accomplished. Additionally, the study on reproductive interaction between sympatric lampreys and salmonids was conducted. Study results revealed, that sea trout has specific spawning site preferences at the stream-, reach- and microhabitat scale, and are related with optimal conditions for egg survival. Vertical hydraulic gradient of... [to full text]

William Henry Fry (1813-1864) and George Frederick Bristow (1825-1898) were the first important composers of grand opera in the United States. They were both avid promoters of American music and American composers during a most unstable time in American history--the mid-nineteenth century just prior to the American Civil War.The present study includes in Chapter I a survey of American culture in the mid-nineteenth century, and in Chapters II and III, brief biographical sketches of W. H. Fry and G. F. Bristow. The main aim of the study has been to explore American culture during the period of approximately 1845 to 1855, and then to show that W. H. Fry's opera Leonora and G. F. Bristow's opera Rip Van Winkle are products of that culture. A general musical analysis of the two operas under consideration is given as evidence of their relationship to the Italian operatic style of the mid nineteenth century. An attempt has been made to find specific examples in both Leonora and Rip Van Winkle that canbe shown to be reflections of the musical culture of Europe with which Fry and Bristow were familiar. The main characteristics of Italian opera, such as: melodramatic plots, popular-type melodies, expressive solo voice, orchestral coloratura sections (particularly for the prima donna), and colorful folk-like songs in this work.Fry was one of the leaders of his time in asserting the thesis that Americans, if they were ever going to develop a native art, must escape their subservience to foreign influence. The irony of the situation is that Fry himself was not able to break away from the European influence in his opera Leonora, except in his use of the English language.George Frederick Bristow, whose life spanned almost the entire nineteenth and the beginnings of American culture.Bristow's opera Rip Van Winkle is written in a style one would expect from a nineteenth-century musician. He tended to write music that was basically diatonic with a spice of chromaticism. Many of the arias, and most of the choruses, are presented in a simple, straightforward style which tends to give the opera a folk-like quality, while some other arias are in an ABA structure, and fit the style of Italian operatic arias of the time. A few of Bristow's melodies are in the French style of the period--that is, they are dance-like in character--and therefore are significant reminders that he was also familiar with nineteenth century French opera.What interest there was in opera in the United States in the mid-nineteenth century was focused primarily on Italian opera, and William Henry Fry and George Frederick Bristow wrote operas in that style.

The aim of this thesis was to test and compare the effect of four selected and in present commonly used medical treatments on other species of fish in recirculating aquaculture system (RAS). This presented work was divided into two separate experiments dealing with curative baths for fry of pikeperch.The fry was raised in ponds, feeded by natural food, with the intention of adaptating for RAS after a bath. Baths were targeted against parasitic and bacterial diseases by using Bellasav, SAVO Original, formaldehyde and Chloramine T. The curative baths took 30 minutes after which the fish were transferred to clean water where the mortality within 24 hours and the efficacy of the preparation within 24 hours was monitored. In the first experiment were used fish with an average weight of 0.23+-0.05 g and a total lenght of 31.7+-2.5 mm at the age of 35 days. The tested doses were 0.5; 1; 1.5; 2; 5; 10 and 50 ml.m-3 for Bellasav, 1; 5; 10; 20 and 50 ml.m-3 for SAVO Original, 0.5; 1; 1.5; 2.5; 5; 10; 15; 30; 45 and 50 ml.100 l-1 for formaldehyde and 10; 20; 30; 40; 50; 100; 150 and 200 mg.l-1 for Chloramine T. The best efficacy was achieved at the concentration dose 1.5 ml.m-3 for Bellasav. The concentration dose 10 ml.m-3 of SAVO Original only reduced parasitic infection by one degree. An effective dose of formaldehyde was 1 ml.100 l-1 which reduced the parasitic infection by two degrees. The most effective preparation was Chloramine T at the concentration dose of 30 mg.l-1. In the second experiment were used fish with an average weight of 1.6+-0.4 g and a total lenght of 60.4+-3.56 mm at the age of 70 days. The tested doses were 10; 20 and 50 ml.m-3 for Bellasav, 10; 20 and 50 ml.m-3 for SAVO Original, 2.5; 5 and 10 ml.100 l-1 for formaldehyde and 40; 150 and 200 mg.l-1 for Chloramine T. The best efficacy was achieved at the concentration dose 20 ml.m-3 for Bellasav and 10 ml.m-3 for SAVO Original. The most effective dose for formaldehyde was 2.5 ml.100 l-1 which reduced the bacterial infection in fish skin by two degrees. The most effective preparation was Chloramine T again at the concentration dose 40 mg.l-1.

This thesis deals with important factors that affect the temporal organization of emergence and early survival of Baltic salmon (Salmo salar L.). The study population was obtained from the Norrfors hatchery (63°50'N,20°05'E), Umeälven (Ume river) in Northern Sweden. The main objectives of the thesis has been to study; a: the effect of female and egg characteristics on embryonic survival, b: the effect of egg size, temperature and photoperiod on the emergence pattern and c: the impact of early or late emergence on survival in relation to predation and limited territorial space. The main results are summarized as follows: (1) Fecundity and egg size increased with increasing weight of females. No effect of female size were found on egg colour. Longer impoundment and later stripping increase egg colour. Egg mortality was not correlated with egg colour. Stripping date was found to have the strongest effect on mortality. (2) Egg size had no effect on the timing of emergence but fry of different egg size emerged synchronously. Fry from large eggs left the gravel as heavier fry and with a larger proportion of yolk left compared to fry from small eggs. (3) The number of days and number of degree days from hatching to 50% emergence decreased exponentially with increasing temperature. Synchronization of emergence increased with increasing temperature. Fry emerged with more yolk at 12 °C compared to 6 °C. (4) Eggs kept in a LD 16:8 light regime hatched mainly during the light period, while eggs kept in constant darkness hatched continously over a 24 hour period. Alevins kept at different light regimes (light>4h) from hatching until emergence left the gravel during the dark period. Daylength had no effect on the annual onset of emergence. (5) In a laboratory stream channel, predator presence at emergence increased mortality especially in early emerging fry. If the predator was introduced after completed emergence high mortality was noted among late emerging fry. The presence of fish predators and a limited territorial space for fry seemed to make early and late emergence hazardous and to favour a "peak" emergence. In the presence of a predator the fry changed their behaviour by reducing their swimming activity. / digitalisering@umu.se

O ovo tem sido estudado por sua riqueza nutricional, por apresentar interesse industrial, como matéria-prima, e pelo seu elevado conteúdo de colesterol. Ao mesmo tempo, por sua susceptibilidade à contaminação por salmonela, principalmente, é proposta a irradiação ionizante como medida sanitária. O colesterol está sujeito à oxidação, facilitada por vários fatores, entre os quais a radiação ionizante. Os óxidos de colesterol formados, por sua vez, apresentam propriedades biológicas prejudiciais à saúde, relacionadas com a aterogenicidade, citotoxicidade, carcinogenicidade e mutagenicidade, além de outras manifestações. Os objetivos deste trabalho foram avaliar o efeito da radiação ionizante sobre o pH, viscosidade e cor, além da estabilidade oxidativa do colesterol, em ovos crus armazenados e processados. Com o aumento nas doses utilizadas (1, 2 e 3 kGy) houve redução na viscosidade da clara e na cor da gema, além do aumento da oxidação lipídica, medida através das substâncias que reagem ao ácido tiobarbitúrico (TBARS). Parâmetros como umidade, lípides totais e colesterol das gemas não foram influenciados. No caso da umidade e do colesterol, houve alteração significativa pelo armazenamento (30 dias, a 4ºC). O somatório dos óxidos analisados não variou com a irradiação, só individualmente, contudo variaram com o armazenamento. O processamento térmico provocou um aumento significativo das TBARS, mas apesar disso, o somatório dos óxidos não diferiu entre os tratamentos. / The egg have being studied due its nutritional wealth, for show industrial interest as a raw material, e due its higher cholesterol content. At the same time, due its susceptibility to contamination mainly with salmonella, it is being proposed the ionizating radiation as a hygienic measure. Cholesterol is subject to oxidation, that it is facilitated by several factors, among them ionizating radiation. Formed cholesterol oxides, by its turn, show harmful biological properties to human health, as atherogenicity, cytotoxicity, carcinogenicity and mutagenicity, among others. The objectives of this work were evaluate the effect of ionizating radiation over pH, viscosity and color, besides the oxidative stability of cholesterol, in storaged and processed crude eggs. With the increasement of used doses (1, 2 and 3 KGy), there was an reduction in the viscosity of the egg white and in the color yolk egg, besides the increase in lipidic oxidation, measured through tiobarbituric acid-reactive substances (TBARS). Specifications as humidity, total lipids and egg yolk cholesterol were not influenced. In the subject of humidity and of cholesterol, there was an meaningful alteration due storage (30 days in 4ºC). The sum of the analyzed oxides didn\'t variate with the irradiation, only individually, although it did vary with storage. The themical processing caused an meaningful increase of TBARS, but despite this, the oxides sum didn\'t differed between treatments.

Egg stocking in rivers and streams is a common measure to support and re-introduce salmonid populations. To ensure the success of egg stocking programs, knowledge of the early life stages of juveniles including dispersal ability and habitat preferences of fry is a prerequisite. This study was conducted to investigate downstream dispersal patterns and habitat use of young of the year brown trout in a mid-sized, channelized, boreal river in Sweden. Eyed trout eggs were stocked in February of 2021. During August of the same year, 2-3 months after emergence, trout were sampled by electrofishing within 1 km downstream of the stocking sites and each individual point of capture was recorded by GPS. In addition, data on riverbank slope, shoreline irregularity, stream bed substrate, water velocity and water depth were collected for each of the sampling sections. The results showed that trout fry were distributed throughout the 1 km long sampled sections and that the density of fry did not increase towards the stocking points. The observed variation in the distribution of trout fry was best explained by the riverbank slope. Approximately twice as high fry densities were found in reaches with gentle compared to medium and steep bank slopes. The differences are suggested to be an effect of 1) stream marginal water velocity differences during high flows affecting fry occupancy, and 2) that gentle slopes were often accompanied by shallow water, preferred by fry. These findings may provide helpful knowledge for fisheries managers to optimize the outcome of egg stocking and river restoration activities regarding fry recruitment. / Romutsättning i vattendrag är en vanlig åtgärd för att stärka och återetablera populationer av laxartade fiskar. För att lyckas med romutsättningar krävs kunskap om ynglens spridningsförmåga och habitatpreferenser. Denna studie genomfördes för att undersöka spridningsmönster och habitatval av ensomrig öring i en medelstor kanaliserad älv i Sverige. Ögonpunktad rom sattes ut i februari 2021. Under augusti samma år, 2-3 månader efter att ynglen lämnat lekgruset elfiskades 1 km långa sträckor direkt nedströms utsättningsplatserna. De fångade individernas position registrerades med GPS. Data över strandkantens lutning, strandzonens flikighet, bottensubstrat, vattenhastighet och djup samlades in för varje elfiskesträcka. Resultatet visade att öringyngel spridit sig över hela de 1 km långa elfiskesträckorna, och att tätheterna av yngel inte ökade med minskat avstånd till utsättningspunkterna. Den observerade variationen i fördelningen av öringyngel förklarades bäst av strandkantens lutning. Ungefär dubbelt så hög täthet av yngel förekom i sträckor med flack jämfört med medel och brant lutning. Skillnaderna föreslås vara en effekt av 1) skillnader i vattenhastighet under höga vattenflöden som påverkar ynglens möjligheter till att bibehålla sin position i habitatet, och 2) att flack lutning av strandkanten ofta åtföljdes av grunt vatten vilket föredras av yngel. Dessa upptäckter kan bidra med värdefull kunskap för att optimera romutsättningar och restaureringar i avseende på rekrytering av årsyngel.

No description available.

Vissa vattenkraftverk drivs med korttidsreglering som möjliggör snabb anpassning av elproduktion, vilket sker genom hastiga förändringar i vattenflöde. Flera olika typer av organismer påverkas negativt av korttidsreglering, till exempel fiskar. En möjlig konsekvens är strandning, vilket innebär att fiskar hamnar i torrlagt substrat eller annat ogynnsamt habitat. Risken för strandning påverkas av flera faktorer. I denna studie undersöktes hur strandningsrisk hos öringyngel (Salmo trutta) påverkas av tillgång till skydd och ljusförhållande, där prediktionerna var att strandningsrisken skulle vara större vid tillgång till skydd och i mörker. Dessa två faktorer testades i en 2x2 design. Det fanns en tendens till en större andel strandade yngel vid tillgång till skydd (48 ± 8,2 %) jämfört med när det inte fanns skydd (35,7 ± 23,7 %) och en större andel strandade vid ljusa förhållanden (50,2 ± 16 %) än i mörker (33,4 ± 17,3 %). Påverkan av tillgång till skydd på strandningsrisk var inte annorlunda vid de olika ljusförhållandena. Utifrån dessa resultat är rekommendationen för att minska strandningsrisken hos öringyngel att flödesreglering genomförs i mörker och att bottenstrukturen beaktas, vilket måste göras i varje enskilt fall. / Some hydropower stations use hydropeaking to be able to swiftly adjust electricity production, which is done through rapid alterations in water flow. Several types of organisms are negatively affected by hydropeaking, including fishes. One possible consequence of hydropeaking is stranding, which occurs when fish are separated from the water body and end up in dewatered substrate. The risk of stranding is influenced by several factors. The aim of this study was to investigate how stranding risk in brown trout fry (Salmo trutta) is affected by shelter availability and light conditions. The predictions were that stranding risk would be higher in conditions with available shelters and in darkness. The two factors were tested in a 2x2-design. There was a tendency for stranding rate to be higher when shelters were available (48 ± 8.2 %) compared to when there were none (35.7 ± 23.7 %), and stranding rate was higher in light (50.2 ± 16 %) than in darkness (33.4 ± 17.3 %). The effect of shelter availability on stranding risk did not differ between the two light treatments. Based on these results, in order to reduce stranding risk in brown trout fry the recommendation is that flow regulation should be carried out in darkness and that the bottom structure should be considered, which must be done on a case-by-case basis.

No description available.