<p>The passage efficiency of downstream migrating brown trout (Salmo trutta) smolts past two hydropower plants in the River Emån, southeastern Sweden, was evaluated by telemetry. From 26 April to 17 May 2005, 40 wild brown trout smolts were radio-tagged, and their positions were recorded daily until 14 June. Approximately 45% of the individuals passed both power plants, and 15% made it to the sea, some 28 km downstream of the power plants. About 20% of the individuals ceased migrating, residing in a lotic habitat. Mortality due to predation was 33%, and the predation rate was higher in the power plant dams than it was downstream of the power plants. Turbine-induced mortality was greater in the upper power plant (40%) than in the lower one (13%). Fish that chose the alternative routes, through the gates, swam past the upper dam faster than fish that swam through the turbines. The results confirm previous work in the river, namely that measures need to be taken to improve passage efficiency past the power plants, particularly passage of the upper power plant. Such measures are of crucial importance if the nature-like bypass channels at the power plants in Finsjö are going to have any long-term effects on the brown trout population.</p> / <p>Passageeffektiviteten för nedströms vandrande havsöringssmolt (Salmo trutta) förbi två vattenkraftverk i Emån, i sydöstra Sverige, utvärderades med telemetri. Från 26 april till och med 17 maj 2005 märktes 40 vilda havsöringssmolt med radiosändare och de positionsbestämdes dagligen till och med 14 juni. Ungefär 45% av individerna passerade båda kraftverken, och 15% klarade sig till havet, cirka 28 km nedströms kraftverken. Omkring 20% av individerna avbröt vandringen och stannade i ett lotiskt habitat. Mortalitet på grund av predation uppgick till 33%, och predationshastigheten var högre i kraftverksdammarna än nedströms kraftverken. Den turbininducerade mortaliteten var högre i det övre kraftverket (40%) än i det nedre (13%). Det gick fortare att passera den övre kraftverksdammen för fisk som valde de alternativa rutterna, genom dammluckorna, jämfört med att passera genom turbinerna. Dessa resultat bekräftar tidigare studier i ån, nämligen att åtgärder krävs för att förbättra passageeffektiviteten förbi kraftverken, i synnerhet passagen av det övre kraftverket. Sådana åtgärder är av avgörande betydelse om de naturlika fiskvägarna vid kraftverken i Finsjö ska få några långsiktiga effekter på havsöringspopulationen.</p>

Superchilling is a method that can be used to prolong the shelf life of foods by partial freezing. Knowledge of the effects of this method on both the shelf life and quality of foods is important in order to find optimal processing and storage conditions and is of great importance both for the industry and for the consumers. Different raw materials of muscle foods were studied with the purpose of creating a basis for further improvements of both the process and the storage conditions. Products from the commercially important species pork (both roasts and rib steaks), Atlantic salmon (both vacuum packed and wrapped fillets) and Atlantic cod (vacuum packed fillets) were chosen to represent different muscle foods. Based on both sensory and microbial evaluations, the superchilled storage improved shelf life of pork roasts from 2 to 16 weeks, and shelf life might even be further prolonged if temperature is kept more constant. The H2S-producing bacteria in superchilled cod fillets did not exceed the limit of consumption during the whole storage period of six weeks, while the microbial shelf life of the ice chilled fillets was estimated to be 8 days after processing. Quality changes have been studied with focus on biochemical and physiochemical properties. One of the major goals in meat and fish processing is the ability to retain water and it was observed that drip loss was lower in superchilled samples compared to traditionally chilled samples in all species studied. However, the subsequent liquid loss was higher both in pork roasts and in cod fillets. The extractability of protein was used as a tool to monitor protein denaturation. It was found that myofibrillar proteins denatured more easily during superchilled than during traditionally chilled storage both in salmon and in cod fillets. This was confirmed by electrophoresis in salmon. The amount of free amino acids were higher in cod than in salmon and increased more during superchilled storage than during ice chilled storage indicating exoproteolytic activity during storage. Activities of cathepsins B and B + L in salmon fillets were relatively stable during the storage period in all storage groups, demonstrating that these enzymes are not deactivated at the selected storage temperatures and may therefore lead to softening during subsequent chilled storage. In superchilled samples of all species studied, white spots emerged on the product surface. However, the appearance of spots did not correspond either to higher drip loss or to higher microbial growth on surface of these samples. On the contrary, the total plate counts of superchilled samples were lower than of the other storage groups. This observation also applied to iron agar counts on cod fillets. These findings are interpreted as a strong indication of that the spots most likely were not of microbial origin. The optimal superchilling process and storage conditions remains to be found for the products studied. From the present results it is reasonable to suggest that optimal storage temperature for the vacuum packed salmon fillets is found between the superchilled temperatures in the present experiments. The quality both of the pork roasts and the cod fillets would probably benefit from a storage temperature slightly closer to 0 °C than those studied. It can also be assumed that the control of the superchilling process is more essential to cod than to salmon and pork. In addition, the properties of the raw material are crucial in order to obtain high quality of products after processing and storage. / Paper I-III are reprinted with kind permission from Elsevier, sciencedirect.com

The passage efficiency of downstream migrating brown trout (Salmo trutta) smolts past two hydropower plants in the River Emån, southeastern Sweden, was evaluated by telemetry. From 26 April to 17 May 2005, 40 wild brown trout smolts were radio-tagged, and their positions were recorded daily until 14 June. Approximately 45% of the individuals passed both power plants, and 15% made it to the sea, some 28 km downstream of the power plants. About 20% of the individuals ceased migrating, residing in a lotic habitat. Mortality due to predation was 33%, and the predation rate was higher in the power plant dams than it was downstream of the power plants. Turbine-induced mortality was greater in the upper power plant (40%) than in the lower one (13%). Fish that chose the alternative routes, through the gates, swam past the upper dam faster than fish that swam through the turbines. The results confirm previous work in the river, namely that measures need to be taken to improve passage efficiency past the power plants, particularly passage of the upper power plant. Such measures are of crucial importance if the nature-like bypass channels at the power plants in Finsjö are going to have any long-term effects on the brown trout population. / Passageeffektiviteten för nedströms vandrande havsöringssmolt (Salmo trutta) förbi två vattenkraftverk i Emån, i sydöstra Sverige, utvärderades med telemetri. Från 26 april till och med 17 maj 2005 märktes 40 vilda havsöringssmolt med radiosändare och de positionsbestämdes dagligen till och med 14 juni. Ungefär 45% av individerna passerade båda kraftverken, och 15% klarade sig till havet, cirka 28 km nedströms kraftverken. Omkring 20% av individerna avbröt vandringen och stannade i ett lotiskt habitat. Mortalitet på grund av predation uppgick till 33%, och predationshastigheten var högre i kraftverksdammarna än nedströms kraftverken. Den turbininducerade mortaliteten var högre i det övre kraftverket (40%) än i det nedre (13%). Det gick fortare att passera den övre kraftverksdammen för fisk som valde de alternativa rutterna, genom dammluckorna, jämfört med att passera genom turbinerna. Dessa resultat bekräftar tidigare studier i ån, nämligen att åtgärder krävs för att förbättra passageeffektiviteten förbi kraftverken, i synnerhet passagen av det övre kraftverket. Sådana åtgärder är av avgörande betydelse om de naturlika fiskvägarna vid kraftverken i Finsjö ska få några långsiktiga effekter på havsöringspopulationen.

Les anàlisis realitzades en cent deu poblacions de truita comuna (Salmo trutta) que abarquen el seu rang natural de distribució indiquen que el patró filogenètic es relaciona amb les tres grans vessants on es troba distribuïda l'espècie: ponto-càspia, atlàntica i mediterrània. Aquesta diferenciació estaria associada a l'aïllament de les vessants durant el Quaternari. L'origen de l'espècie es relaciona amb la vessant ponto-càspia, d'acord amb els models biogeogràfics que postulen l'origen asiàtic de la ictiofauna europea. S'ha detectat també un segon nivell de divergència dins de cada vessant que dóna com a resultat l'existència de sis llinatges evolutius: Atlàntic i Duero a la vessant atlàntica, els llinatges Adriàtic, Mediterrani i Marmoratus als rius mediterranis, i el llinatge Danubi a la zona ponto-càspia.Les glaciacions del Pleistocè han modificat profundament el rang de distribució de la truita comuna, especialment a la vessant atlàntica, on s'han proposat quatre grans refugis glacials: a l'est de la capa de gel, a Europa central, a l'entorn del canal de la Mànega i a l'entorn del golf de Biscaia; tot i que només els tres primers haurien participat en la recolonització del nord d'Europa al final de l'última glaciació. El quart refugi, que inclou el sud de França i el Cantàbric hauria estat l'origen de l'expansió cap al sud durant el Pleistocè Superior d'un grup de poblacions distribuïdes actualment a la vessant atlàntica ibèrica, i també hauria servit de base per a l'expansió cap al nord d'altres grups de truita durant interglacials anteriors.A la vessant atlàntica de la peninsula Ibèrica, l'estructura poblacional es troba associada a la xarxa hidrogràfica i es determinen fins a cinc unitats poblacionals: les truites dels rius Cantàbrics, les del Miño, les del Duero, les del Tajo i les del Guadalquivir. Les poblacions del Guadalquivir pertanyerien a un grup d'influència mediterrània. Els marcadors d'al·lozims i de DNA mitocondrial es troben fortament correlacionats en aquesta vessant, on apunten cap als mateixos grups de poblacions. Per contra, els rius de la vessant mediterrània haurien estat colonitzats pels llinatges Adriàtic i Mediterrani i s'hauria produït una intensa intergradació secundària entre aquests llinatges durant els períodes glacials a partir de l'expansió de les poblacions retingudes a les capçaleres durant els interglacials. Els grups de hibridació, l'aïllament i la deriva en el període interglacial fa que els grups de poblacions identificats pels marcadors d'al·lozims i de DNA mitocondrial no coincideixin. / The analyses performed in one hundred and ten brown trout (Salmo trutta) populations that cover its native European distribution, shows that the phylogenetic pattern is associated with the three major basins occupied by the species: Ponto-Caspian, Atlantic and Mediterranean. This differentiation is related with basin isolations during the Quaternary. The origin of the species is placed in the Ponto-Caspian region, in clear agreement with biogeographic models that postulates the Asian origin of European ichthyofauna. Further divergence occurred in the mid-lower Pleistocene generated the actual lineages: Atlantic and Duero in the Atlantic basin, Adriatic, Mediterranean and Marmoratus lineages in the Mediterranean rivers and the Danubian lineage in the Ponto-Caspian area.Pleistocene glacial periods have deeply modified the distribution range of brown trout, mainly in the Atlantic basin, where four major glacial refugia have been proposed: (i), at the East side of the ice sheet, (ii), in Central Europe, (iii), around the English Channel and (iv), around the Bay of Biscay. Only the three first seem to be involved in the recolonization of North Europe at the end of the last glacial period. The fourth glacial refugia, placed in Southern France and the Cantrabrian Sea area, would have been the origin of a southern expansion during Late Pleistocene. Nowadays, those trout populations are distributed in the Atlantic basin of the Iberian Peninsula. This glacial refugia could also be involved in older recolonizations of North-Europe previous to last glacial process.Brown trout population structure in areas at the Atlantic basin of the Iberian Peninsula is associated with river network. Thus, five trout population groups could be determined: trout from the Cantabrian Rivers, from the Miño River, from the Duero River, from the Tajo River and trout populations from the Guadalquivir basin. These last populations show a strong Mediterranean influence. In this basin, comparisons involving allozyme and mitochondrial DNA data are strongly correlated and points towards the same population groups. The rivers in the Mediterranean basin have been colonized by Adriatic and Mediterranean lineages, and strong secondary intergradations are reported among them during glacial periods. Population groups identified by allozyme and mitochondrial DNA do not agree as a consequence of this intergradation, as well as isolation and genetic drift during interglacial periods.

This thesis evaluates the adaptive significance of annual cycles on the migratory behaviour of Baltic salmon (Salmo salar L.). The studies have included field experiments as well as laboratory studies gf maturity and migratory behaviour patterns of smolts and postsmolts mainly from the Angerman river population. Contrasting to the phenotypical elasticity in life-history traits, Baltic salmon was found to have a rather strict temporal organization of their annual behavioural patterns. Two year old smolted Baltic salmon showed drastic differences in migratory behaviour when compared in tanks containing either fresh or brackish water. Freshwater kept fish showed an annual cycle where downstream displacement in the upper water column was followed by a stationary behaviour, indicating a readaption to a freshwater life. Fish in brackish water behaved as a migratory fish throughout tne study. Baltic salmon also showed differences in maturation patterns in fresh and brackish water. Three summer old males detained in freshwater all matured sexually the following autumn. If transferred to sea and kept in net- pens a low proportion matured, mainly previously matured males. Furthermore there was a size- dependent relationship of sexual rematuration. Many small previously matured males did not migrate, similarly small previolusly matured males were unable to respond to shifts in the environment. With larger size the alternatives of sexual maturation and high growth rate wi more related to the environmental conditions the fish experienced. A hypothesis has been tested assuming that Baltic salmon migration is influenced by an annual time program. According to the hypothesis the migratory distance covered in the Baltic should be a result of a migratory activity sequence rather than a definite goal orientation. Fish detained before release generally showed a shorter distance between release point and area of recapture compared to fish released at normal time of smoltrun. The migratory distance appeared to be inversly related to the period of delay before release. A seasonal difference in migratory propensity was recorded. An instantaneous mortality curve for Baltic salmon during seaward migration and early sea-phase was estimated based on recapture data on sequentially related fish. The weekly mortality rate decreased from an initial mean of 271 during onset of migration, to 3.51 in mean during autumn. The high risk of mortality during the first part of migration indicated that strong selective forces act on a precise seasonal timing of migration. / <p>Diss. (sammanfattning) Umeå : Umeå universitet, 1988, härtill 5 uppsatser</p> / digitalisering@umu

Submitted by Noeme Timbo (noeme.timbo@metodista.br) on 2017-01-25T14:17:49Z No. of bitstreams: 1 JOVANIR LAGE.pdf: 1704014 bytes, checksum: 7348405f68bec44a617b0f44c997f3c5 (MD5) / Made available in DSpace on 2017-01-25T14:17:49Z (GMT). No. of bitstreams: 1 JOVANIR LAGE.pdf: 1704014 bytes, checksum: 7348405f68bec44a617b0f44c997f3c5 (MD5) Previous issue date: 2016-09-29 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / This research is organized from the problem of the opposition between “wicked and righteous” going through the different types of texts from the Persian period under the following question: Who is the [v'r' in Israeli society, and because this term appears with greater intensity in the post-exilic period? This research aims mainly to research the reasons that influenced the introduction of [v'r' terminology “wicked” in certain psalms, such as identification of the enemy. Secondary objectives of our research are: (1) analyze the conceptual formation of [v'r' in its anti-positive feature with qyDIc;; “righteous” emphasizing the ethical axis, characterized as one of the word interpretations; (2) to study the function of the word within the Psalms of Lament, supported the exegetical study of Psalm 55; (3) to understand critically, analyzing the implications of the use of [v'r' as evil representation in the social development of the Jewish community in the post-exilic period. In our approach we intend treat such study from ethical axis, extending the research to the analysis of interpretative motivations Solidarity without Old Testament context / A presente pesquisa organiza-se a partir do problema da contraposição entre “malfeitores e justos” que atravessa os diversos tipos de textos do período persa sob a seguinte pergunta: Quem é o [v'r' na sociedade israelita, e porque este termo surge com maior intensidade no período pós-exílio? O objetivo desta pesquisa visa principalmente, a investigação das razões que influenciaram a introdução da terminologia [v'r' “malfeitor” em determinados salmos, como identificação do inimigo. Os objetivos secundários de nossa investigação serão: (1) analisar a formação conceitual do [v'r' dentro de sua característica anti-positiva com o qyDIc; “justo” enfatizando o eixo ético, caracterizado como uma das interpretações do termo; (2) estudar a função do termo dentro dos Salmos de Lamentação, apoiado no estudo exegético do Salmo 55; (3) entender de forma crítica, a análise das implicações do uso do [v'r' como representação da maldade no desenvolvimento social da comunidade israelita no período pós-exílio. Em nossa abordagem pretendemos tratar de tal estudo a partir do eixo ético, estendendo a investigação para a análise das motivações interpretativas da solidariedade no contexto veterotestamentário.

Made available in DSpace on 2016-08-03T12:20:30Z (GMT). No. of bitstreams: 1 Santa Angela Cabrera.pdf: 405823 bytes, checksum: 839b3afec519db242d7ef380052c9cda (MD5) Previous issue date: 2007-11-21 / Conselho Nacional de Desenvolvimento Científico e Tecnológico / In Latin America we have little bibliography on Psalm 23. Nevertheless, we have a few researchers who are able to dialogue academically with European scholars about our object of study. In spite of the great attractiveness of this text in the pastoral world in our continent, exigetically we have come up short with this Psalm, which has become our justification for making a study of this Psalm. Psalm 23 in enwrapped in the Psalter. It is Hebrew poetry, which is characterized by the repetition of the meaning of its phrases. Its content is between the lines, thanks to the frequent use of images, symbols, and figures. For these and for other reasons, it is difficult to point to its date of origin, but it must be pre-exilic. Our text reveals, as a vital place, a liturgical community. This community is located in the Jerusalem temple. There are there, each in turn, priests, levites, organic intellectuals, in sum, persons who have witnessed up close the controversy of a person who has sought refuge in the temple and who has found a supportive place in the sanctuary. From this we deduce that Psalm 23 was written by someone with poetic sensibility, inspired by the life of the person sheltered. The Psalmist has experience Yahweh s care. There in the temple, in the area of the kingdom of Yahweh, those who threaten him cannot capture him. The reasons for persecution may suggest debt matters and at the same time matters of justice.. Once in the sanctuary, he is lacking for nothing, because his shepherd/ king provides him with what he needs, that is, food, drink, protection, security, dignity and fraternity. The agressors are witnesses of the happy state of their enemy, but they can do nothing to him. For this reason the Psalmist has no fear and, in the presence of Yahweh, finds comfort. Yahweh as shepherd/ king is host to the one he protects. From the innocence of the refugee is born the air of celebration, because the liturgical community celebrates the salvation which has been received. The graces received have for the Psalmist a communitarian repercussion, the good and the solidatiry which he has experienced will come back to those who surround him, not by obligation but as gratitude. For reasons fo security and gratitude the Psalmist wishes to remain in the house of Yahweh.(AU) / Na América Latina temos pouca bibliografia sobre o Salmo 23. No entanto, contamos com alguns pesquisadores que podem dialogar academicamente com cientistas europeus sobre nosso objeto de estudo. Apesar do grande atrativo deste texto no mundo pastoral de nosso continente, o aporte exegético deste Salmo estava em dívida, o que se tem convertido numa de nossa justificação científica para o estudo do Salmo 23. O Salmo 23 se incrusta dentro do saltério. É poesia hebraica, a que se caracteriza pela repetição do sentido de suas frases. Seu conteúdo está nas entrelinhas pelo uso freqüente de imagens, símbolos e figuras. Por estas e outras razões é difícil assinalar sua data de origem, mas deve ser pré-exílico. Nosso texto revela, como lugar vital, uma comunidade litúrgica. Essa comunidade está localizada no templo de Jerusalém. Ali se encontram, por sua vez, sacerdotes, levitas, intelectuais orgânicos; enfim, pessoas que têm testemunhado de perto a controvérsia de uma pessoa refugiada no templo, a que tem achado no santuário um lugar de amparo. Desde aqui deduzimos que o Salmo 23 foi escrito por alguém de sensibilidade poética, inspirado na vida do asilado. O salmista tem experimentado os cuidados de Javé. Ali, no templo, na área do reino de Javé, seus ameaçadores não podem capturá-lo. Os motivos de perseguição podem sugerir assuntos de dívidas e, ao mesmo tempo, assuntos de justiça. Uma vez no santuário, não carece de nada, porque seu pastor/rei lhe fornece o que precisa, isto é, comida, bebida, proteção, segurança, dignidade e fraternidade. Os agressores são testemunhas do estado de felicidade de seu inimigo, mas não podem fazer-lhe nada. Por isso o salmista, não teme e, na presença de Javé, encontra seu consolo. Javé, como pastor/rei, hospeda a seu protegido. Pela inocência reconhecida do refugiado, nasce o ambiente de festa, porque a comunidade litúrgica celebra a salvação alcançada. As graças recebidas têm para o salmista uma repercussão comunitária, o bem e a solidariedade que experimentou voltarão aos que o circundam, não por obrigação e sim por gratidão. Por assuntos de segurança e agradecimento o salmista deseja permanecer na casa de Javé.(AU)

Made available in DSpace on 2016-08-03T12:20:32Z (GMT). No. of bitstreams: 1 Antonio Renato Gusso.pdf: 648983 bytes, checksum: caecfda435486024a6683919ec8d219d (MD5) Previous issue date: 2007-10-29 / This thesis, based on exegesis, defends the position that the curses in Psalm 137 should be interpreted by taking into account the principle of reciprocity which belongs to the practice of justice in the OT, the famous eye for na eye, tooth for a tooth. It presents aids for the interpretation of curses in the Psalms; makes an analysis of the current stateof the question; verifies the coherence or incoherence of the term imprecatory Psalm ; treats the difficult question of the historical context of the Psalms; and, more, highlights certain points which create difficulties for the Christian interpretation of this type of literature. It treats questions of text, of structure, of literary genre, of authorship, and of the context of Psalm 137 in life and history. Further, it presents parallels to this genre in the Biblical world and compares versions of Psalm 137 in Portuguese. It shows that in the OT a word was treated as having intrinsic power; it verifies how, normally, curses were used in the OT in general, preparing the way for the verification of its specific use in Psalm 137; it brings together a rapid historical retrospective showing the long trajectory of the conflicts of Isarael/ Judah with Edom and Babylon, which leads the Psalmist to feel he has the right to ask that these two nations be destroyed and suffer; it also raises the possibility that Psalm 137 is not the only one in the Psalter to contain curses against Edom and Babylon, and poi8nts out that in this composition there are one self-curse and two curses, one against Edom and the other against Babyolon, all of them taking into consideration the principal of reciprocitgy in OT justice.(AU) / Esta tese, baseada na exegese, defende que as maldições do Salmo 137 devem ser interpretadas levando-se em conta o princípio da reciprocidade praticado na justiça do AT, o famoso "olho por olho, dente por dente". Apresenta auxílios para a interpretação das maldições nos salmos; analisa o estado atual da questão; verifica a coerência ou não da utilização do termo "Salmo Imprecatório"; trata da difícil questão do contexto histórico dos salmos e, ainda, destaca alguns pontos que dificultam a interpretação cristã deste tipo de literatura. Ela trata das questões do texto, da estrutura, do gênero literário, da autoria, e do contexto de vida e histórico do Salmo 137. Além disso, apresenta paralelos deste gênero no mundo bíblico e compara versões do Salmo 137 em português. Mostra que no AT a palavra era tratada como algo que possui poder intrinseco; verifica como, normalmente, era feito o uso das maldições no AT em geral, preparando o caminho para a verificação de seu uso específico no Salmo 137; faz uma rápida retrospectiva histórica mostrando a longa trajetória de desavenças de Israel/Judá com Edom e Babilônia, o que leva o salmista a sentir-se no direito de pedir que estas duas nações sejam destruídas e sofram; levanta, ainda, a possibilidade do Salmo 137 não ser o único do Saltério com maldições contra Edom e Babilônia, e destaca que nesta composição existe uma automaldição e duas maldições, uma contra Edom e outra contra Babilônia, todas elas levando em conta o princípio da reciprocidade na justiça do AT.(AU)

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&gt;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

Förvaltning av lax är en komplicerad uppgift som kräver stor förståelse för både laxen och de antropogena effekter som påverkar den. Vattenkraftverk har stor påverkan på laxen genom oregelbundna flöden, reducerad vattenföring och barriärer i vandringsvägar. Laxen är beroende av att vandra för att optimera tillväxt, överlevnad och reproduktion. Östersjöns laxbestånd minskade kraftigt mellan 1950- och 1980-talet till följd av dammutbyggnad och överfiske. Redan i början av 1900-talet började det lokala laxbeståndet i älven Ljusnan att sjunka av samma orsaker. Idag finns ingen lax kvar i Ljusnan. För att möjliggöra en återintroduktion av lax krävs möjlighet för vandring och tillgång på reproduktionshabitat. Bollnäsströmmarna bedöms med sina 6,6 km historiskt ha stått för 25 % av hela Ljusnans laxproduktion. Syftet med denna studie var att simulera en återintroduktion av lax i Bollnäsströmmarna och att genom sårbarhetsanalys undersöka om utplantering av romkorn kan resultera i en överlevande laxpopulation. Simuleringarna utfördes med dagens förutsättningar med undantag av att de passagefria kraftverken ersattes med passagelösningar av bästa möjliga teknik. Utöver detta undersöktes effekter av ökad passagedödlighet förbi kraftverken, habitatåterställande åtgärder och utökade supplementära utsättningar av romkorn. Sammanlagt nio sårbarhetsanalyser utfördes i simuleringsprogrammet Vortex. Resultatet av studien visar att utplantering av romkorn kan producera en laxpopulation som överlever under en hundraårsperiod. Efter en initial populationsökning under tio år sjunker dock tillväxten konstant resterande nittio år vilket med största sannolikhet hade resulterat i en utdöd population över en större tidsrymd. Den potentiella laxpopulationen var mycket känslig för ökad passagedödlighet med en hög utdöenderisk efter endast en liten ökning. Både habitatåterställande åtgärder och supplementära utsättningar av rom gav positiva effekter på populationsstorleken men inget scenario lyckades producera ett stabilt och livskraftigt bestånd vilket tyder på att fler åtgärder krävs för ett lyckat återintroduktionsprojekt. / Conservation of salmon is a complicated task that requires understanding both the biology of salmon and the anthropogenic impacts affecting it. Atlantic salmon is dependent on its migration to optimize growth, survival and reproduction. Hydropower plants affect salmon by causing highly irregular flows, reduced discharge and barriers along migration routes. The salmon stocks of the Baltic Sea declined considerably between the 1950s and 1980s as a result of dam development and overfishing. For the same reasons the local salmon stock in the River Ljusnan, Sweden began to decline already in the early 1900s, and today there are no salmon left in the River Ljusnan. To restore the population, actions to mediate migration and access to reproduction habitats and rearing habitats are needed. The 6.6 km long river section, “Bollnäsströmmarna”, is estimated to have accounted for 25 % of the total salmon production in the River Ljusnan. The aim of this study was to simulate a reintroduction of Atlantic salmon in Bollnäsströmmarna, and using a population viability analysis (PVA), investigate if stocking of eggs can result in a viable salmon population. Simulations were made on the basis of today’s conditions, with the condition that best practice passage solutions are implemented. In addition, the effects of increased passage mortality, habitat restoration and increased supplementary stocking of eggs were simulated. A total of nine PVA simulation (n= 100) scenarios were performed in the Vortex simulation program. The results of the study show that stocking of eggs can produce a salmon population that has a minimum extinction risk over a one-hundred year period. However, after an initial population increase over ten years, population growth steadily declines for the remaining ninety years, which most likely would result in extinction if a period longer than 100 years was considered. The salmon population was very sensitive to an increase in passage mortality, with a high extinction risk after only a small increase in mortality. Both habitat restoration and increased supplementary stocking impacted the population size positively, but no scenario produced a stable and viable population, which indicates that more measures are required for a successful long-term reintroduction.