Ferskvannsbehandling av lakselus

Lakselusa fører til ca. 500 millioner kroner i tap i forhold til dødelighet, tap av tilvekst, samt nedgradering av kvalitet og utgifter i forhold til behandling og arbeid. Og vi opplever et økende resistensproblem med lakselusa. Jeg skal med denne eksperimentielle oppgaven se nærmere på ferskvann som behandlingsmetode mot lakselus. Jeg skal evaluere og registrere, i samarbeid med GIFAS, hvordan preadulte hunnlus (Lepeophtheirus salmonis) reagerer på ulike saliniteter gjennom bruk av bioassay. Samt være med på å gjennomføre og analysere resultater fra et semi – kommersielt forsøk med brønnbåt fylt med ferskvann. Det ble brukt preadulte hunnlus i boiassay, på grunn av lave lusetall og lite kjønnsmoden hunnlus. Resultatet viste at all preadult hunnlus døde etter en time eksponering for ferskvann. All lus som var i kontrollgruppen med sjøvann overlevde ikke, slik at man kan anta at lusa var noe svekket. Man kan ikke konkludere hundre prosent på dette resultatet. Det totale resultatet fra brønnbåtforsøket viste en signifikant nedgang på 1.29 lus per fisk før behandling (alle livsstadier) til 0.05 lus per fisk etter eksponering for ferskvann i overkant av tre timer. Det vil si en nedgang på 97%. Kjønnsmoden hunnlus hadde en signifikant nedgang på 0.39 lus per fisk før behandling, til 0.03 lus etter eksponering for ferskvann. Konklusjonen er at ferskvann viser et klart potensial for å brukes som en del av en integrert tilnærming for å kontrollere lakselus – infeksjoner. Med en kombinasjon av kommersielle legemidler mot lus og ferskvann kan man oppnå en kortere behandlingstid og større dødelighet på kjønnsmoden lus. Muligheten for å kunne kommersialisere en slik behandlingsmetode avhenger mye av tilgjengeligheten av brønnbåt, god og stor nok ferskvannskilde, og om det er mulig å blande kommersielle legemidler uten at det oppstår problemer

Sustainable Aquaculture in Norway: Aligning Policy Intentions with Environmental Realities

The aquaculture industry in Norway, with its steady growth, has not only become one of the country's most important industries but also a significant player on the global stage. Its importance is underscored by the fact that it is a major contributor to the country's economy. However, sustainability has emerged as a central concern, especially considering the industry's criticism for increased emissions, diseases, and mortality rates in salmon pollution. Balancing economic growth and environmental concerns is a major challenge in the industry, one that requires careful consideration and strategic planning. This study, employing a qualitative research method with document analysis, delves into the relationship between the Norwegian government's political intentions as expressed in 'Meld. St. 20 (2019-2020)’ and the actual environmental and economic outcomes reported in 'Risikorapport Norsk Fiskeoppdrett 2024'. Through a systematic analysis of these two documents, the study uncovers the trajectory of the aquaculture industry in Norway. The study reveals both alignment and tensions between the political intentions and actual results. The analysis demonstrates a broad correspondence between the sustainability strategies outlined in the whitepaper and the reported environmental challenges. However, the effectiveness of these strategies varies significantly across different production areas. The framework plays a pivotal role in shaping environmental and economic outcomes, but practical implementation poses challenges across all areas. The study also uncovers potential links and trade-offs between the environmental and economic aspects of sustainable aquaculture. These findings significantly contribute to our understanding of the development of the aquaculture industry in Norway and the alignment and tensions between political intentions and actual results

Hindrer Nordhordlandsbroen smoltens utvandring?

Den dramatiske nedgangen av laksebestanden i Vosso har brakt flere institusjoner sammen for å undersøke betydningen av menneskeskapte forhold for denne utviklingen. De siste årene har søkelyset i hovedsak vært rettet mot lakselus og andre faktorer som kan påvirke smoltutvandringen. Havforskningsinstituttet har undersøkt hvilken betydning Norhordlandsbroen kan ha

A novel lice control method: photochemical treatment (Photolice)

Control of salmon lice has long been the biggest challenge for the further development of a sustainable industry. Preventive measures are expected to play an increasing role, but experience suggests that drug treatment will still be an important tool in an effective lice strategy. Today's control options are limited by unwanted environmental effects or resistance issues linked to the use of chemicals. This project has tested whether light-activated chemicals used in e.g. human cancer medicine could be an effective and environmentally friendly treatment method against salmon lice. The project consisted of three parts, which first examined the direct effect of substances on salmon lice (screening phase), after which selected substances were tested on lice-infected fish and finally on organisms from the environment around the cage. Nine different compounds were tested, where three of the tested compounds induced mortality when applied directly to salmon lice but did not induce loss of salmon lice when applied to infected fish. The tested compounds had no negative effects on fish welfare, nor did they induce mortality or change the behavior of rock-pool shrimps, which were used as an example of an organism that might be affected. We conclude that the use of photoactivated compounds may be possible to eliminate salmon lice from fish in aquaculture environments, but further studies are necessary.A novel lice control method: photochemical treatment (Photolice)publishedVersio

Sea lice feeding behavior of wild and hatchery lumpfish (Cyclopterus lumpus) under hatchery conditions.

In 2014 Norway contributed 1.2 million tons of the world production of farmed salmon. Norway is the world’s largest producer of farmed salmon, and the species is among the top five species, quantity consumed, in the major seafood markets. Infection by sea lice is the greatest disease challenge currently limiting the production of Atlantic salmon globally. Sea lice are responsible for a wide range of distresses to the fish, from mild skin damage to stress-induced mortality, which can be a tremendous economic burden for the Atlantic farmed industry. Biological control by cleaner fish has become a common approach to delouse salmon. Lumpfish is a cold-water marine fish used as cleaner fish, and salmon cages contain 93%-97% fewer sea lice with lumpfish present than without them. The use of lumpfish as biological control raises ethical concerns for poor welfare and high mortality of the cleaner fish when stocked in sea cages. Good welfare of lumpfish is essential because it affects their ability to delouse salmon, and a higher welfare will have several advantages, including improving delousing efficacy and having economic value as sea lice cause economic losses to the industry. There are few studies on the effectiveness of cleaner fish, and it is essential to characterize the behavior of individuals eating most actively on sea lice so that choosing lumpfish as cleaner fish in the future can be more efficient. The primary aim of this study was to observe feeding behavior of wild and hatchery lumpfish. This was done by comparing number and type of attacks by wild versus hatchery lumpfish to delouse salmon under hatchery conditions. Stomach content from gastric lavage was also used to examine how many lice were eaten by lumpfish. A secondary aim was to evaluate the swimming activity of wild and hatchery lumpfish under two different light conditions; 1) once lights are turned on, and 2) once the lights start dimming. Four swimming activities will be evaluated which are 1) hovering, 2) swimming, 3) attached swimming, and 4) burst swimming. Ten hatchery and ten wild lumpfish were introduced together with eight sea lice-infested salmon of approximately 300 g in a 500 l tanks over a 3-weeks experimental period. The experiment was duplicated in another 500 l tank. The number and type of attacks and the swimming activity of the lumpfish were recorded for posterior video analysis. Additionally, the number of sea lice consumed by each lumpfish was examined by a gastric lavage three times over the experimental period. Hatchery lumpfish seemed better fit for delousing based on the higher number of sea lice in their stomach, 55 lice compared to 27 by wild individuals, and a higher number of attacks recorded. Five individuals were evaluated more closely, because they had the highest number of attacks performed and highest number of lice in their stomach. The individuals were shown to have 5 to 23 sea lice in their stomach on total days sampled and performed attacks within most of the attack types. Hatchery lumpfish showed to be bolder and more aggressive than wild lumpfish

Modellering av smittsomme lakseluslarver - bakgrunnsdata for Havforskningsinstituttets modellprodukt til Trafikklyssystemet, 2020

Siden det er vanskelig å få en fullstendig oversikt over luseinfeksjoner på laksefisk langs hele kysten ved hjelp av tradisjonelle feltobservasjoner, har Havforskningsinstituttet utviklet en lakselusmodell som utfyller observasjonene, både i tid og rom. Les mer om overvåking på https://www.hi.no/hi/temasider/arter/lakselus/overvaking-av-lakselus Rapporten inneholder figurer som viser antall klekte nauplier per uke i de 13 produksjonsområdene. Videre beskrives og vises det figurer over hvordan tettheten av kopepoditter variere i tid og rom innen de ulike produksjonsområdene. Til slutt inneholder rapporten en diskusjon av utveksling av kopepoditter mellom produksjonsområdene. Rapporten inngår i Havforskningsinstituttets bidrag til ekspertgruppen for trafikklyssystemet og grunnlaget for vurdering av lakselusindusert dødelighet per produksjonsområde i 2020.publishedVersio

Risikorapport norsk fiskeoppdrett 2020 : Risiko knyttet til dødelighet hos utvandrende postsmolt laks som følge av utslipp av lakselus fra fiskeoppdrett

Havforskningsinstituttet har siden 2011 gitt ut en årlig risikorapport for norsk fiskeoppdrett med fokus på miljøeffekter og dyrevelferd. Arbeidet med rapporten har vist at akvakultur har et svært komplekst risikobilde, og det er varierende kunnskapsnivå og grad av tilgjengelige overvåkningsdata knyttet til de ulike miljøpåvirkningene. Lakselus og rømt oppdrettslaks regnes per i dag som de største truslene for villaksen og i 2017 ble det innført en handlingsregel basert på lakselus som miljøindikator som regulerer kapasitetsendringer i oppdrettsnæringen (Trafikklyssystemet). Der ekspertgruppen i Trafikklyssystemet beskriver nåværende status i produksjonsområdene basert på de siste to årene, ønsker vi med denne risikovurderingen å skape økt forståelse og innsikt rundt de antatt viktigste risikofaktorene knyttet til effekten av lakselus på utvandrende postsmolt laks, hvordan disse samspiller, og konsekvensen av disse. Argumentasjonen og vurderingene våre bygger på data og annen tilgjengelig kunnskap fra perioden 2012-2019.publishedVersio

Farmed salmonids drive the abundance, ecology and evolution of parasitic salmon lice in Norway

Sea cage fish farming is typically open to the environment, with disease transmission possible between farmed and wild hosts. In salmonid aquaculture, salmon louse Lepeophtheirus salmonis infestations cause production losses, reduce welfare for farmed fish and increase infestation rates for wild fish populations. The high density of hosts in farms likely also shifts the coevolutionary arms race between host and parasite, with ecological and evolutionary consequences for the salmon louse. Using farm-reported salmon and louse abundances and publicly reported estimates of wild salmonid host abundances and the salmon lice they carry, we estimated (1) the relative abundance of farmed and wild salmonid hosts and (2) the relative importance of each for the abundance of salmon lice for the coastal zone of Norway from 1998 to 2017. Farmed hosts increased in importance over time with the expansion of the industry. From 2013 to 2017, farmed salmonids outnumbered wild salmonids by 267-281:1. By 2017, farmed salmonids accounted for 99.6% of available hosts and produced 99.1% of adult female salmon lice and 97.6% of mated (ovigerous) adult female salmon lice in Norwegian coastal waters. The persistent dominance of farmed hosts has clear implications: (1) management decisions that aim to limit lice abundance can be guided by lice data from farms alone, as lice on wild salmonids make a trivial contribution to the national lice population; and (2) strategies to prevent or treat lice infestations are vulnerable to the evolution of resistance, as the pool of wild hosts is inconsequential and will not act as a refuge large enough to stem the evolution of resistance. As the Norwegian salmon industry expands and salmon lice infestations continue, farmed salmon will drive the ecology and evolution of salmon lice.publishedVersio

Kunnskapsstatus lakselus 2020 - Effekt av lakselus på vill laksefisk (2010-2019)

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