During the last two hundred years many wetlands and streams in Sweden have been lowered to provide land for agriculture and forestry. Some of the coastal wetlands and streams probably served as spawning sites for certain species of fish in the Baltic Sea, but the present situation is not well known. As standardized methods to monitor fish in running waters are carried out during late summer or autumn, there is a need for methods to sample spring-spawning fish in these streams.The aim of this study was to survey the lower kilometer stretch of Hammerstaån in Stockholm, to investigate the extent to which the stream is used by spring-spawning fish. Furthermore, the study aims to evaluate a new type of survey fishing gill net calledströmöversiktsnät (SÖN). This was done by comparing the catch of fish by SÖN with that of fyke nets.

The Swedish forest have about 100 000 km of watercourses and it?s an important structure in Swedish landscapes and catchments. In some of the watercourses lives spieces like the freshwater pearl mussel (Margaritifera margaritifera) and brown trout (Salmo trutta) which both are sensitive for inteference from the forestry. The new EU water framework directive has a goal that all surface water will have high or good ecological- and good chemical status at latest by the 22nd December of 2015. The study has been made in the catchment of Håltjärnsbäcken and it is from a national perspective one of the most valuable streams in Sweden and which also have been included in a LIFE-project. The catchment is situated within the Eco-park of Malingsbo-Kloten and managed by Sveaskog AB.

Många av Europas öringpopulationer har dålig rekrytering. Flera variabler som påverkar rekryteringen av dessa bestånd har uppmärksammats i forskningen genom åren. Forskningen har oftast bedrivits på specifika bestånd, för att se vilka variabler som påverkar just dem. I  Pinnarpsbäcken i Kinda kommun finns ett öringbestånd som har vikande populationssiffror. Bäcken har klassats som riksintressant och delar av  den blev 2007 registrerad som ett Natura 2000-område.

The life cycle of the anadromous Atlantic salmon (Salmo salar) can span large geographic, political, and socio-economic boundaries. Management strategies and regulations that only concentrate on small spatial scales often overlook larger basin-wide problems, especially relating to post-spawn seaward migration. In this master thesis one entire migration cycle of wild adult Atlantic salmon in the unregulated northern Swedish river Vindelälven was monitored by radio-telemetry tracking during upstream spawning migration and downstream seaward migration back to the Baltic Sea. The effect of ladder passage variables (time to pass, total time in the ladder, passage day over the ladder) at a fish ladder downstream in the river Umeälven, as well as fish size, were evaluated to determine if differences in upstream migration distance in the river Vindelälven could be observed. Ladder passage variables did not affect migration distance, but size exhibited a negative relationship to migration distance.

Lax är en av de mest frekvent förekommande matfiskarna i våra hem. Den största delen av den lax som når hem och restaurang är odlad. Det är allt vanligare med sjukdomar hos lax som odlas. Kocken ställs inför svåra frågor gällande den odlade fiskens kvalité. En viktig aspekt är att ha kunskap om de eventuella sjukdomar som förekommer i vår samtids fiskodling.Syftet med detta arbete är att undersöka den i vardagens måltider förekommande råvaran odlad lax utifrån hur sjukdomar påverkar fiskens kvalité.Den information som ges i de fem vetenskapliga artiklar arbetet är baserat på presenteras i avsnittet resultat.

In many regulated rivers, authorities have stocked hatchery salmon to compensate for loss of wild populations. However, hatchery fish have not always behaved as wild fish do, and stocking them has not always fully compensated for the loss of wild fish. The purpose of this study was to compare swimming behaviour in the river before spawning, the choice of spawning areas and body size between wild and hatchery-reared salmon in the river Klarälven. Salmon behaviour in the river before spawning was analyzed using radio telemetry. The salmon were caught at Forshaga power plant, radio-tagged and returned to Klarälven at Ekshärad, 107 km from the river?s mouth.

Användning av Informations- och kommunikationsteknik (IKT) är idag ett naturligt inslag i många människors vardag. Samtidigt uppmärksammas risken med digitala klyftor av flera samhällsinstanser. I detta sammanhang nämns äldre som en av de grupper som riskerar att hamna efter, vilket i förlängningen kan leda till ett utanförskap från den demokratiska processen på grund av bristande tillgång till eller kunskap om datorer och Internet. Studiens syfte är att belysa äldres upplevelser och erfarenheter av datorer och IT och sin delaktighet i IT-samhället idag. Studien är inspirerad av etnografisk metod och har ett socialkonstruktionistiskt perspektiv där ålder kan förstås som en skapad social kategori.

Laxen är en anadrom fiskart som reproducerar sig i sötvatten men lever huvuddelen av sitt vuxna liv i saltvatten. På grund av vattenkraftens dammbyggen hindras laxen att göra dessa habitatbyten och reproduktionen drabbas. För att kompensera för minskade laxstammar sätter vattenkraftbolagen varje år ut miljontals odlad laxsmolt i vattendrag som mynnar ut i östersjön. I Umeälven släpps 80000 laxsmolt ut årligen. Tidigare rapporter visar att överlevnaden hos dessa är lägre än hos vild smolt.

Habitat mapping was conducted in the main stem of River Vindelälven in the autumn of 2009 along the salmon distribution area. The aim was to estimate the quantity of potential reproduction areas, including spawning and juvenile rearing habitats. The mapping included 61 km of various stream sections along the river length of 269 km. The total area of stream habitats was estimated to 647 ha of which 396 ha (61%) were considered as either potential or optimal juvenile nursery habitats. The area of these two habitat classes were used to estimate the smolt production in the river by using electro fishing densities of juveniles (0+ per 100 m2).

The upstream spawning migration of Atlantic salmon (Salmo salar) at the confluence area between the power-station outlet and the bypass-channel in river Umeälven (flow 430 m3s-1) was compared in 2004 and 2005, two years with different experimental flow-regimes. In 2004 the water flow in the bypass-channel was altered during the day with increased flows during the nights while the water flow in 2005 mainly was altered between the weekdays and weekends. Salmon showed altered migratory behaviour in this confluence area, assessed with telemetry (n=116) and echo-sounding, with up- or downstream responses depending on flow-changes in both the bypass and the power station outlet. Increased turbine flow through the power-station generally attracted salmon into the tunnel outlet area while increased spill-flows facilitated salmon to enter the bypass. Echo-sounding in the confluence area showed an increased swimming activity up- and downstream due to time in the day and flow-rates through the tunnel outlet. No changes in activity could be detected due to increasing or decreasing flow through the hydro-power facility.

Due to exploitation of the world?s rivers, the upstream migration of anadromous species is frequently delayed or even prevented. To mitigate these problems and allow fish to migrate past obstacles, structures such as fish ladders have been developed. However, recent studies show that many of the present fish passage facilities are deficient. Monitoring and evaluation of passage facilities is therefore crucial to enable necessary adjustments.

A large number of rivers in northern Sweden have hydropower developments that cause negative effects on both up- and downstream migrations of anadromous species like Atlantic salmon. So far, most attention has focused on the hindrances of adult fish during their upstream spawning migration. However, since turbines in power stations cause losses on downstream passing fish, the focus on negative effects on smolts has increased. The aim of this study was to compare three different causes of losses of salmon smolts passing downstream through a power station area in the flow-controlled River Åbyälven in northern Sweden.A total of 61 wild salmon smolts were caught and radio-tagged in the River Åbyälven during their downstream migration in June 2009. The salmon smolts were released at three locations, 1.1 km upstream from the power station, in the turbine intake and in the upper part of a fishway, acting both for up- and downstream fish passage.

Vaccination of fish can be assumed to cause pain. This study was designed to see if we can minimize the suffering of fish following vaccination. Fishes are cold-blooded animals and thus more primitive than warm-blooded animals. Despite this, many organs, e.g. the nervous system, have the same basic structure as that of other vertebrates. The fibre system for conducting pain is more diffuse than in humans.