Search results for "kalanviljely"
showing 10 items of 23 documents
Potential for managing life history diversity in a commercially exploited intermediate predator, the goldsinny wrasse (Ctenolabrus rupestris)
2019
Abstract Small-bodied wrasse species are important for structuring coastal marine ecosystems but are also increasingly harvested as parasite cleaners on farmed salmon. Identifying management regulations that will support long-term sustainability of wrasse fisheries is challenging, because there is still limited knowledge about the impacts of fisheries on the demography of these intermediate predators in their natural environments. To this end, we studied individual growth histories of goldsinny wrasse (Ctenolabrus rupestris) at a fine spatial scale across replicated marine protected areas (MPAs) and areas open to commercial harvesting on the Norwegian coast. The MPAs were established 1–7 ye…
Rich resource environment of fish farms facilitates phenotypic variation and virulence in an opportunistic fish pathogen
2020
Phenotypic variation is suggested to facilitate the persistence of environmentally growing pathogens under environmental change. Here, we hypothesized that the intensive farming environment induces higher phenotypic variation in microbial pathogens than natural environment, because of high stochasticity for growth and stronger survival selection compared to the natural environment. We tested the hypothesis with an opportunistic fish pathogen Flavobacterium columnare isolated either from fish farms or from natural waters. We measured growth parameters of two morphotypes from all isolates in different resource concentrations and two temperatures relevant for the occurrence of disease epidemic…
Comparing RADseq and microsatellites for estimating genetic diversity and relatedness : Implications for brown trout conservation
2019
The conservation and management of endangered species requires information on their genetic diversity, relatedness and population structure. The main genetic markers applied for these questions are microsatellites and single nucleotide polymorphisms (SNPs), the latter of which remain the more resource demanding approach in most cases. Here, we compare the performance of two approaches, SNPs obtained by restriction-site-associated DNA sequencing (RADseq) and 16 DNA microsatellite loci, for estimating genetic diversity, relatedness and genetic differentiation of three, small, geographically close wild brown trout (Salmo trutta) populations and a regionally used hatchery strain. The genetic di…
Kuhan (Sander lucioperca) soveltuvuus kolmen imumatoloislajin väli-isännäksi: alttius infektiolle ja loisten vaikutus kalan käyttäytymiseen
2008
Flavobacterium columnare in Finnish fish farming : characterisation and putative disease management strategies
2005
Lotta-Riina Suomalainen selvitti väitöskirjatyössään syitä flavobakteeritaudin lisääntymiselle. Flavobacterium columnare -bakteerin aiheuttama kalakuolleisuus on vakava uhka suomalaiselle poikaskalan tuotannolle. Flavobakteeri-infektiot muodostavat suurimman osan kalanviljelyssä diagnostisoiduista tautitapauksista ja niiden haitta elinkeinolle on merkittävä. Flavobacterium columnare -bakteeri aiheuttaa kalanpoikasille vakavia kidus- ja ihotulehduksia. Tappiot kalanviljelijälle ovat mittavat, sillä jopa 100 % sairastuneista kaloista voi kuolla. Tauti esiintyy kesäaikaan yleensä viljellyillä lohikaloilla. Sen esiintyminen on lisääntynyt viime vuosien aikana, mutta syitä siihen ei tiedetä. The…
Screening of microalgae and LED grow light spectra for effective removal of dissolved nutrients from cold-water recirculating aquaculture system (RAS…
2019
Popularity of recirculating aquaculture systems (RAS) is increasing. Because of the high water recirculation rate, dissolved nutrients originating from fish feed are concentrated enough in RAS wastewater (WW) to enable growth of primary producers, e.g. microalgae. This study evaluated nitrate-nitrogen (NO3-N) and phosphate-phosphorus (PO4-P) removal efficiency of ten temperate zone freshwater microalgae species during their exponential growth phase in unfiltered RAS WW at 17 ± 0.5 °C. Growth and nutrient uptake efficiency of six green and four non-green microalgae strains were compared between WW and reference growth medium in batch monocultures. The effect of three different LED grow light…
The influence of infective dose, nutrient availability and coinfection on virulence of Flavobacterium columnare : implications of intensive aquacultu…
2016
Ecological factors are known to affect disease dynamics and even lead to disease emergence. Especially in opportunistic, environmentally transmitted pathogens, the environment may significantly contribute to pathogen virulence. Intensive farming, including aquaculture, has been suggested to create conditions favouring development of highly virulent pathogens. At Finnish fish farms, epidemics caused by opportunistic Flavobacterium columnare have been constantly increasing in their prevalence and severity since the 1980’s. Yet, factors behind the increased virulence of the pathogen and their mechanisms of action have largely remained unsolved. In this thesis, I explore the effects of infectio…
Transmission of Diplostomum spathaceum between intermediate hosts
2004
FM Anssi Karvonen tutki väitöskirjassaan kalojen silmän linssissä elävän Diplostomum spathaceum -imumatoloisen ekologiaa. Tutkimus tarjoaa uutta tietoa lois-isäntä -suhteiden evoluutiosta sekä perustietoa, jonka avulla voidaan suunnitella loisen torjuntamenetelmiä kalanviljelyssä. Tutkimukset ovat lisäksi osa laajempaa projektia, jossa tutkitaan D. spathaceum -loisen elinkierron ekologiaa ja evoluutiota kaikissa elinkierron vaiheissa. Sen yhtenä päämääränä on kehittää elinkierron matemaattinen malli, jonka avulla on mahdollista kehittää ekologisesti kestäviä menetelmiä D. spathaceum -loisen torjuntaan.D. spathaceum on yksi luonnonkalojen yleisimmistä loisista Suomessa ja sitä esiintyy myös …
Salmon lice in the Pacific Ocean show evidence of evolved resistance to parasiticide treatment
2022
AbstractParasitic salmon lice (Lepeophtheirus salmonis) threaten the economic and ecological sustainability of salmon farming, and their evolved resistance to treatment with emamectin benzoate (EMB) has been a major problem for salmon farming in the Atlantic Ocean. In contrast, the Pacific Ocean, where wild salmon are far more abundant, has not seen widespread evolution of EMB-resistant lice. Here, we use EMB bioassays and counts of lice on farms from the Broughton Archipelago, Canada—a core region of salmon farming in the Pacific—to show that EMB sensitivity has dramatically decreased since 2010, concurrent with marked decrease in the field efficacy of EMB treatments. Notably, these bioass…
Effects of weekend starvation and the duration of daily feeding on production parameters of rainbow trout Oncorhynchus mykiss
2021
It would often be practical to starve the cultivated fishes over the weekends, e.g. to save in labour costs. We evaluated the possibility that domesticated juvenile rainbow trout (Oncorhynchus mykiss) could compensate for the lost growth of the 2-day weekend starvation by either hyperphagic response and/or by lower feed conversion ratio, compared to the fish fed every day in an 8-week experiment. Rainbow trout (initial weight c. 30 g, temperature 16 °C) starved during the weekends were able to increase feed intake during the weekdays clearly above the intake of the control fish after the first two weekends, also seen as an increase of the compensation coefficients over the last four weeks o…