Sökresultat:
36 Uppsatser om Atlantic herring - Sida 1 av 3
Tankar kring Torsk : Isotopanalyser av torskkotor för att undersöka vikten av torskimport i medeltida Sverige
This essay discusses the import of cod (Gadus morhua) in Sweden during the Middle Ages through isotope analysis of cod vertebrae. The isotope analysis is used to trace the cods origin to either the Baltic Sea or the Atlantic Ocean. The bones were subjected to d13C, d15N and d34S analysis; 64 of the analyzed bones met the quality criteria. The isotop data showed that import of Atlantic cod was significant in medeval Sweden. The analysis suggests that there is no specific time or event that the sites start to import cod but this varies from site to site. .
Politisk Mobilisering och Kollektiva och Sociala Identitetskonstruktioner -en studie om dess interaktion med Nicaraguas Atlantregion som empiriskt exempel
This thesis is concerned with political mobilization and the construction of a collective andsocial identity. The main purpose of the study is theoretical which emphasize their interaction.In order to do this I study the two phenomenons by seeing them as cases of each other. Wecannot understand one of the two phenomenons without taking into account the other as well.In addition, the secondary aim of my thesis is empirical. I use the political transformationduring the 70th and 80th on the eastern seaboard of Nicaragua to relate my theoretical analysisof political mobilization and the construction of identities. Nicaragua will provide mytheoretical analysis with new insights.
Rosenlunds bankar : Erosion och förändring sedan 1960
During the 1960´s and 1970´s the number of grey seals in the Baltic Sea was decreasing rapidly, mostly due to hunting and toxic substances like DDT and PCB. When hunting became less intense and toxic substances decreased in the environment the grey seal population started to increase. Today grey seals are found common in the Baltic Sea and have started to become a big treat and a problem to the fishing industry. The grey seal destroys and enters fishing traps and consumes large quantities of the fish that have been caught.The knowledge of the grey seal, like abundance and food preferences, is today limited. It is also important to define the position of the grey seal in the ecosystem in the Baltic Sea and to be able to predict changes that could occur if the population would rapidly decrease or increase.
"Fallbacks" - betydelsen av vandringstid för Atlantlax (Salmo salar L.) som faller nedströms vandringshinder
In Lake Vänern, Sweden, there is an endemic population of Atlantic salmon (Salmo salar L.) that lives its entire life in fresh water. The salmon is hindered from migrating to its natural spawning sites in the northern part of the River Klarälven by nine hydro-electric power plants. None of the hydro-electric power plants have fishways so that salmon migrating upstream or downstream may pass. In the current situation, the upward migrating salmon are caught in a fish trap at the most downstream located power plant in Forshaga. From there, the salmon are driven in a truck, past eight power plants and released a few kilometers upstream of the eighth power plant at Edsforsen.
Full Circle: upstream and downstream migration of Atlantic salmon (Salmo salar) in the northern Swedish river Vindelälven
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.
Födosammansättning hos gråsäl (Halichoerus grypus) samt test av flotte för insamling av sälfekalier.
During the 1960´s and 1970´s the number of grey seals in the Baltic Sea was decreasing rapidly, mostly due to hunting and toxic substances like DDT and PCB. When hunting became less intense and toxic substances decreased in the environment the grey seal population started to increase. Today grey seals are found common in the Baltic Sea and have started to become a big treat and a problem to the fishing industry. The grey seal destroys and enters fishing traps and consumes large quantities of the fish that have been caught.The knowledge of the grey seal, like abundance and food preferences, is today limited. It is also important to define the position of the grey seal in the ecosystem in the Baltic Sea and to be able to predict changes that could occur if the population would rapidly decrease or increase.
Fysiska strukturer i Umeälvens gamla älvfåra och dess inverkan på laxsmoltens utvandringsframgång
The survival of hatchery reared smolts is generally low after release. To get a better understanding of what variables affecting migration success, Atlantic salmon smolts were studied during their out-migration in the old river channel in the lower part of river Umeälven. The area consists of shifting habitat and complex structures which causes difficulties for smolt on their migration out to sea. The aim of this study was to try to determine the effects of feed restriction, fin conditions and different physical barriers in the river, on the migratory behavior of Atlantic salmon smolts in the river Umeälven.
The river was divided into six different sections using acoustic receivers strategically deployed along the river. Two-year old hatchery-reared smolts (n=150), in three different weight classes, were tagged with acoustic transmitters.
Utveckling av armstöd med joysticklösning för båtsäte
Syftet med det här examensarbetet var att konstruera och formge ett armstöd med integrerad joystick för båtsätet Atlantic Seat. Projektet genomfördes vid Medinova AB som är ett produktutvecklingsföretag med fokus på ergonomi och i första hand arbetar med säten och styrsystem för snabba motorbåtar. Atlantic Seat är ett säte med god stötupptagningsförmåga och har två målgrupper i dels yrkesbåtar såsom Sjöräddningens och Försvarsmaktens båtar, dels lyxiga fritidsbåtar. Under projektet har ett systematiskt tillvägagångssätt använts i arbetet. De moment som genomgicks var informationsinsamling, problemformulering, problemundersökning, idégenerering, idébedömning samt detaljkonstruktion och formgivning.
Vattenflödets betydelse för fångster av lekvandrande lax (Salmo salar) och öring (Salmo trutta) : En utvärdering av laxfällan vid vattenkraftverket i Forshaga
Many watersheds have lost stocks of migrating fish species because of the development of hydroelectric plants and other fragmenting barriers. The remaining stocks of migrating Atlantic salmon (Salmo salar) and brown trout (Salmo trutta) in River Klarälven, Sweden are five times smaller compared to one hundred years ago. A fish-trap at the hydroelectric plant in Forshaga has been vital for the continued existence of the stocks. This is the first hydroelectric plant of eight, blocking the way to the spawning grounds. Spawners are collected in the trap for both hatchery and transport by truck upstream and past seven more hydroelectric plants to the spawning grounds, where they are released for possible natural reproduction.
Passage efficiency and migration behavior for adult Atlantic salmon at a Half-Ice Harbor fish ladder
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.
Migration losses of Atlantic salmon (Salmo salar L.) smolts at a hydropower station area in River Åbyälven, Northern Sweden : passage fates at a reservoir, a power house and a bypass structure
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.
Termohalin cirkulation i Nordatlanten
Den termohalina cirkulationen är en global havscirkulation driven av densitetsskillnader, som gör att varmt vatten transporteras mot polerna och kallt vatten mot ekvatorn. Densiteten påverkas av temperatur och salinitet (och tryck, som vanligtvis ignoreras). Därför heter cirkulationen termohalin. Saliniteten minskar när vatten tillförs genom nederbörd, havsissmältning eller landavrinning. Saliniteten ökar genom avdunstning och isbildning.
Bruket och arbetarna : Arbets- och anställningsförhållanden vid Åtvidabergs kopparverk 1800-1890
This paper illustrates the working conditions at the copper factory in Åtvidaberg during 1800-1890 from different views. The highest salary was given to the building contractor. Thereafter came in order the rust turners, the garmaker, the melter, the ore booker, the factory supervisor and the garmaker hand. Also the rest of the working conditions for different employees might differ from each other in this order. The mine workers generally earned a little less than the other workers at the factory, and especially the workers in the Bersbo mine.
Dioxinkontaminering i Gävleborgs län : Utbredning, orsaker och åtgärdsanalys
Detta examensarbete syftade till att ta fram ett underlag för en regional åtgärdsplan avseende dibenso-p-dioxiner och dibensofuraner, gemensamt benämnda som PCDD/F eller dioxiner, i Gävleborgs län. Länet har historiskt varit ett av de mest utsatta områdena i Sverige beträffande dessa föroreningar och höga koncentrationer i bland annat strömming har medfört att denna inte får saluföras i övriga EU. I arbetet har resultaten från den rådande forskningen på området studerats för att få kunskap om nuvarande källor och möjliga förklaringar till de fortsatt förhöjda koncentrationerna av dioxiner. Därefter har data från tidigare undersökningar av dioxinkoncentrationer i Gävleborgs län samlats in, sammanställts och använts för att studera hur koncentrationerna varierar geografiskt inom länet. Principalkomponentanalys (PCA) av specifika dioxinkongeners koncentrationer har sedan använts för att försöka identifiera verksamhetstyper som potentiellt kan ha bidragit till föroreningarna på olika platser - en analys som dock är behäftad med stora osäkerheter. De insamlade provresultaten har även använts för att genom massbalansmodellering undersöka återhämtningen i två känt förorenade fjärdar i länet; Norrsundet och Gårdsfjärden.
Den medeltida stadshamnen : Om strandområdets topografi och funktion i tre Öresundsstäder
This essay focuses on the function and development of city harbors during the middle ages in the Scanian part of Öresund. The purpose of the survey is to take a closer look at topography, development and activities on the shores in three coastal cities along the west coast of Scania. The cities that has been part of the survey are: Skanör ? Falsterbo, Malmoe and Landskrona, three cities that follows each other chronologically and that show both similarities and differences in appearance, function and urbanization.The cities of Skanör ? Falsterbo and Malmoe were important market places for the medieval Scania market with the herring fishery in focus. The cities? birth has to be looked upon in relation to these activities.