Browsing Mastergradsoppgaver i fiskeri- og havbruksvitenskap by Author
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Browsing Mastergradsoppgaver i fiskeri- og havbruksvitenskap by Author
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Now showing items 89-93 of 93
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Vang, Birthe (Master thesis; Mastergradsoppgave, 28-Sep-2007)[+][-]
Abstract: Atlantic cod (Gadus morhua L.) is a promising and relatively new species in Norwegian fish farming. Benefits of cod farming includes stable deliveries of fresh cod all year round, and that the supply of a growing marked can be met without depletion of the cod stocks. Improved slaughter procedures by live chilling and reduction of ante mortem stress, give the opportunity to process the fish pre-rigor, usually within 4 hours pm. Such processing not only reduces fillet gaping which often is a serious problem in well-fed cod fishes filleted post-rigor, but may also lower the transportation costs and make the fresh fillets available to the markets at an earlier stage. Little is known about how pre-rigor filleting affects the drip loss of cod fillets, but the low WHC reported for cod might suggest that it is more severe than in salmon. The aims of this thesis were to determine weight and length changes during ice storage of farmed Atlantic cod fillets produced pre- and post-rigor. In addition, biochemical characteristic such as pH, water content and water holding capacity (WHC) of the fillets were determined. The concentrations of proteins, gelatine degrading enzymes and cathepsin D in the muscle and drip losses during storage were also investigated. The results showed that pre-rigor filleting of farmed Atlantic cod resulted in a 10 % weight loss during an 11 day long storage period after slaughter. This loss was twice the amount found in cod filleted post-rigor (5 days post mortem). Such a large weight loss may indicate that pre-rigor production of skinless fillets from farmed cod is not a feasible practice for the industry. The rigor contraction of the pre-rigor produced fillet resulted in a shortening of 27 % on the second day post mortem. At the end of the storage the shortening of the fillets were approximately 19 % while the post-rigor produced fillets merely had contracted 4 %. The shapes of the pre- and post-rigor produced fillets were quite different. Both the myofibrillar and sarcoplasmatic proteins were apparently very stable during ice storage. However, more sensitive methods than general proteinstaining are necessary to obtain detailed knowledge on post-mortem changes of these proteins in the muscles. The proteins present in the drip losses were very similar to the sarcoplamatic proteins extracted from the muscles. However, some degradation could be detected to have occurred in the drips. Both cathepsin D and gelatine degrading enzymes were detected in the drip losses. As with the sarcoplasmatic proteins, these enzyme activities appeared to be less stable in the drips than in the muscles. URI: http://hdl.handle.net/10037/1212 File(s) in this item: 1
Maseropppg%20Birthe%20Vang[1].pdf (2.034Mb) -
Varmedal, Ingrid (Master thesis; Mastergradsoppgave, 22-May-2009)[+][-]
Abstract: Aqueous and organic extracts of the Arctic sponge Aplysilla sulfurea and methanolic extracts from the Arctic phytoplankton Porosira glacialis were fractionated using preparative HPLC into 40 fractions according to the polarity of the components in the extract. The fractions were tested for antibacterial, anticancer and antioxidative activities. After re-chromatography, active fractions were analyzed by mass spectrometry in order to identify components responsible for the confirmed activities. In the organic extracts of the sponge, fractions containing cytotoxic activity were found. Ianthelline, a di-brominated molecule with molecular mass 472.9672 was tentatively identified as the cytotoxic compound. The antibacterial activity of this molecule has previously been published, but the cytotoxicity related to human cancer cell lines has not been reported. The antioxidative activity found in the same fractions was not further investigated due to the likely cytotoxicity of the compound. The semi-aqueous fractions from the pellet of the phytoplankton Porosira glacialis were found to have antioxidative activity. No cytotoxicity was found, and this made the antioxidative components interesting for further investigation by mass spectrometry in order to elucidate the structure. However, the data were complex and not clear, and further investigation will be necessary in order to come to an identification. URI: http://hdl.handle.net/10037/3561 File(s) in this item: 1
thesis.pdf (1.583Mb) -
Weihe, Rúni (Master thesis; Mastergradsoppgave, 15-May-2008)[+][-]
Abstract: Laks blir i all hovedsak solgt som en standardvare og derfor foregår det prinsipielt priskonkurranse på spottmarkedet. Noen oppdrettsnajonser oppnår allikevel gjennomsnittlig mye høyere pris enn andre. Blant disse finner vi Irland som produksjonsmessig er en liten aktør i markedet. Denne studien undersøker hvordan Irland oppnår bedre priser enn konkurrentene i laksemarkedet. Basert på en dyptgående studie av fire sentrale aktører i Irland, gir studien innsikt i hvilke strategier som den irske næring benytter for å posisjonere seg i markedet. Innsikt i disse aktiviteter blir også utforsket for å identifisere potensielle konsekvenser disse resulterer i. For å forstå sammenhengen mellom strategisk valg og posisjonering prensenterer studien sentrale teoretiske bidrag. Porters (1980) bidrag omkring strategi står helt sentralt i litteraturen omkring posisjoneringstemaet og i kombiansjon med Day & Wensleys (1988) konkurransefortrinnsmodell brukes disse som et teoretisk fundament. Barneys (2007) inndeling av differensieringsbaser sammenfatter en stor del av differensieringsmulighetene som finnes og er derfor også en fokal del i teorien. Disse bidrag er med til å strukturere og bearbeide teori og empiri. En eksplorativ forskningsstrategi er adaptert som følge av a priori liten innsikt i temaet. En kombinasjon av kvalitative og kvantitative metoder er brukt til datainnsamling. Halvstrukturerte dybdeintervjuer er utført med fire sentrale irske personer samt bruk av sekundærdata fra for eksempel EFF har bidratt med praktiske opplysninger. Studien avslører flere interessante funn hvorav organisk sertifisert oppdrett og EMS sertifiserte standarder anses som hovedårsakene for sammenhengen mellom irsk strategi og høye laksepriser. Funnene indikerer også at Irland som opprinnelsesland har oppnådd et forholdsvis godt renommé i markedet og at dette påvirker prisen positivt. Irsk laks er et knapphetsprodukt og denne faktoren alene anses derfor som en viktig forklaringsvariabel for de høye irske laksepriser. Resultatene blir diskutert og det kastes lys over implikasjoner. URI: http://hdl.handle.net/10037/1435 File(s) in this item: 1
thesis.pdf (925.2Kb) -
Ytrøy, Egil Henning (Master thesis; Mastergradsoppgave, 15-Nov-2008)[+][-]
Abstract: Since the 1970s, many attempts have been made in Norway to turn blue mussel farming into a growth industry. Total production has increased during the last ten years, but prices have decreased and the value of the Norwegian production has fluctuated greatly. Many blue mussel farming companies have failed. Hence, the results have not been as expected. The Canadian story is different. In contrast to what has happened in Norway, some Canadian provinces – notably Prince Edward Island - have had a great success in blue mussel farming. During the same period they have developed this activity into a viable industry. This thesis compares the development of blue mussel farming in Norway and Canada. Why has the Canadian industry fared better than its Norwegian counterpart? In order to highlight the issue, the thesis focuses on the bottlenecks and barriers for the development of blue mussel production in the two countries and how these challenges have been dealt with. The study is based on interviews with eleven different companies and five different governmental and membership organizations in selected regions in Canada and Norway. In addition, a wide range of secondary sources have been used. The main findings are that the two industries are facing rather similar natural challenges. Toxicity is a common threat and at the moment invasive species is becoming a growing problem in Canada. What differentiates the two industries is that blue mussel farming in Canada was initiated as a response to declining fisheries. This may partly explain why the Canadian industry has been more successful. The infrastructure for industrial support also seems to be better co-ordinated in Canada than in Norway, and the Canadian producers have the benefit of a large domestic market and proximity to the US market, while the Norwegian producers have a small domestic market and greater difficulties gaining access to the well-established European market. However, these conclusions must be regarded as provisional considering the limited amount of data on which this thesis is built. URI: http://hdl.handle.net/10037/1696 File(s) in this item: 1
thesis.pdf (560.2Kb) -
Øseth, Ellen (Master thesis; Mastergradsoppgave, 15-Feb-2008)[+][-]
Abstract: Kongekrabben, Paralithodes camtschaticus, ble satt ut i Barentshavet på 60-tallet av russiske forskere, og har i dag etablert en reproduserende bestand både i russisk og norsk del av Barentshavet. Krabben er en forvaltningsmessig utfordring ettersom den både er en introdusert, fremmed art og en kommersielt lønnsom art. I dag har den en antatt utbredelse fra grensa mot Russland og kanskje ned til Tromsøområdet, og det er indikasjoner på at det er etableringer relativt langt fra kysten, også utenfor 12 nm, i norsk økonomisk sone. Krabben er en fødemessig generalist som har potensial til å fjerne store mengder organismer fra havbunnen, og den foretar sesongmessige vandringer for å skaffe seg føde og for å gyte. Hunnkrabbene kan ha betydelige mengder egg som har en inkubasjonstid på nesten et år og en larvefase på rundt to måneder i våre farvann, med en passiv transport med havstrømmene før den slår seg ned på passende bunnsubstrat. Kjønnsmodning ser ut til å inntreffe ved 110 mm ryggskjoldlengde for både hunner og hanner. Gjennom en nylig fremlagt Stortingsmelding om forvaltning av kongekrabbe skisseres hvordan norske myndigheter ønsker å forvalte denne fremmede arten; både gjennom et utrydningsfiskeri med gitte tiltak for å begrense spredning og gjennom et kommersielt fiskeri innen et geografisk avgrenset område. Der foreslås det å starte et kommersielt fiskeri også etter hunner, men det gjøres ikke noen vurdering av minstestørrelse eller beskatningsgrad for dem. Ut fra biologiske kriterier ser det ut til at et minstemål for hunner på 125 mm ryggskjoldlengde vil være formålstjenlig ut fra et ønske om fortsatt å ha en kommersiell bestand. Med det økende fokus på biologisk mangfold og økosystembasert forvaltning kan det stilles store spørsmålstegn ved den forvaltningsmessige behandlingen av kongekrabbe. Det er en meget stor utfordring å kombinere forvaltning av en introdusert art som en ressurs med grunnelementene i økosystembasert forvaltning. Jeg gjør i denne oppgaven noen betraktninger og kommer med noen anbefalinger i forhold til hvordan dilemmaet rundt kongekrabben kan vurderes og handteres. URI: http://hdl.handle.net/10037/1377 File(s) in this item: 1
thesis.pdf (3.819Mb)
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