Blar i Brage IMR på forfatter "Dempster, Timothy David"
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Acclimation with lice-infested salmon improves cleaner fish delousing performance
Gentry, Katherine; Bui, Samantha; Oppedal, Frode; Bjelland, Reidun Marie; Nola, Velimir; Dempster, Timothy David (Peer reviewed; Journal article, 2021)Securing the welfare and maximising the lice removal efficacy of ~60 million cleaner fish used each year on salmonid farms is essential to develop a productive and ethical industry with low salmon lice Lepeophtheirus ... -
Avlusing med kaldt vann? – effektivitet og laksens velferd — sluttrapport FHF prosjekt 901488
Oppedal, Frode; Stien, Lars Helge; Wright, Daniel William; Moltumyr, Lene; Nilsson, Jonatan; Dempster, Timothy David; Overton, Kathy (Rapport fra havforskningen, Research report, 2019)Termisk behandling av oppdrettslaks med varmt vann blir hyppig brukt av næringen som avlusingsmetode. Behandlingen rapporteres å fjerne mobile lus effektivt, men kan også føre til dårligere fiskevelferd og økt dødelighet. ... -
Cage size affects dissolved oxygen distribution in salmon aquaculture
Oldham, Tina; Oppedal, Frode; Dempster, Timothy David (Journal article; Peer reviewed, 2018)Atlantic salmon aquaculture is shifting toward larger cages, but the water quality implications of this shift are unknown. While larger cages could improve profitability through economies of scale, they may increase the ... -
Depth distribution of the amoebic gill disease agent, Neoparamoeba perurans, in salmon sea-cages
Wright, Daniel W.; Nowak, Barbara; Oppedal, Frode; Bridle, Andrew; Dempster, Timothy David (Journal article; Peer reviewed, 2015-07-16)Identifying where and when parasites occur in farming environments is vital to understand transmission dynamics and develop preventative measures that reduce host-parasite encounters. A major parasite concern for Atlantic ... -
Differential effects of internal tagging depending on depth treatment in Atlantic salmon: a cautionary tale for aquatic animal tag use.
Wright, Daniel William; Stien, Lars Helge; Dempster, Timothy David; Oppedal, Frode (Journal article; Peer reviewed, 2019)Electronic tags are widespread tools for studying aquatic animal behavior; however, tags risk behavioral manipulation and negative welfare outcomes. During an experiment to test behavioral differences of Atlantic salmon ... -
Effect of ectoparasite infestation density and life-history stages on the swimming performance of Atlantic salmon Salmo salar
Bui, Samantha; Dempster, Timothy David; Remen, Mette; Oppedal, Frode (Journal article; Peer reviewed, 2016-06-14)To overcome sustainability obstacles and improve operations, the Atlantic salmon farming industry is testing novel approaches to production. Redistributing farm sites to offshore locations is one such solution; however, ... -
Free-living Neoparamoeba perurans depth distribution is mostly uniform in salmon cages, but reshaped by stratification and potentially extreme fish crowding
Wright, Daniel William; Nowak, Barbara; Oppedal, Frode; Bridle, Andrew; Dempster, Timothy David (Peer reviewed; Journal article, 2017)Understanding the spatio-temporal positioning of hosts and their parasites in free-living states is useful in devising methods to diminish parasite encounters in animal production systems. We explored the potential for ... -
Growth and welfare of submerged Atlantic salmon under continuous lightning
Sievers, Michael; Korsøen, Øyvind Johan; Dempster, Timothy David; Fjelldal, Per Gunnar; Kristiansen, Tore S; Folkedal, Ole; Oppedal, Frode (Peer reviewed; Journal article, 2018)ABSTRACT: Although surface-based cages dominate the marine finfish aquaculture industry, production issues that arise at the surface such as poor environmental conditions and the presence of parasites has spurred interest ... -
High host densities dilute sea lice Lepeophtheirus salmonis loads on individual Atlantic salmon, but do not reduce lice infection success
Samsing, Francisca; Oppedal, Frode; Johansson, David; Bui, Samantha; Dempster, Timothy David (Peer reviewed; Journal article, 2014) -
Limited evidence for differential reproductive fitness of wild Atlantic cod in two areas of high and low salmon farming density
Barrett, Luke; Swearer, Stephen E.; Harboe, Torstein; Karlsen, Ørjan; Meier, Sonnich; Dempster, Timothy David (Journal article; Peer reviewed, 2018)Sea cage fish aquaculture attracts large aggregations of wild fish that feed on farm waste. Fish that associate closely with farms undergo physiological changes, and captive feeding trials indicate possible negative effects ... -
Lyd i lakseoppdrett
Oppedal, Frode; Vindas, Marco; Sivle, Lise Doksæter; de Jong, Karen; Dempster, Timothy David; Forland, Tonje Nesse; Barrett, Luke (Rapport fra havforskningen;2024 - 23, Research report, 2024)Lydnivået på oppdrettsanlegg har økt ettersom anleggene har blitt større, mer mekanisert og bruker en rekke støyende maskiner (arbeids- og brønnbåter, pumper og kompressorer). Lyd brer seg godt under vann og kan høres av ... -
Parasite management in aquaculture exerts selection on salmon louse behaviour
Coates, Andrew; Johnsen, Ingrid Askeland; Dempster, Timothy David; Phillips, Ben (Peer reviewed; Journal article, 2021)The evolution of pest resistance to management strategies is a major challenge for farmed systems. Mitigating the effects of pest adaptation requires identifying the selective pressures imposed by these strategies. In ... -
Salmon lice (Lepeophtheirus salmonis) development times, body size and reproductive outputs follow universal models of temperature dependence
Samsing, Francisca; Oppedal, Frode; Dalvin, Sussie; Johnsen, Ingrid Askeland; Vågseth, Tone; Dempster, Timothy David (Journal article; Peer reviewed, 2016-05-25)Temperatures regulate metabolism of marine ectotherms and thereby influence development, reproduction, and, as a consequence, dispersal. Despite the importance of water temperatures in the epidemiology of marine diseases, ... -
Salmon lice nauplii and copepodids display different vertical migration patterns in response to light
Szetey, Aylah; Wright, Daniel William; Oppedal, Frode; Dempster, Timothy David (Peer reviewed; Journal article, 2021)Light is a fundamental environmental cue which influences the migration of many marine organisms. For the salmon louse Lepeophtheirus salmonis, light is believed to drive the diel vertical migration behaviour of their ... -
Sea lice prevention strategies affect cleaner fish delousing efficacy in commercial Atlantic salmon sea-cages
Gentry, Katherine; Bui, Samantha; Oppedal, Frode; Dempster, Timothy David (Peer reviewed; Journal article, 2020)Over the last 2 decades, cleaner fishes have been employed to remove external sea lice parasites from Atlantic salmon Salmo salar in sea cages. Norway, Scotland, Ireland, and the Faroe Islands combined now use ~60 million ... -
Sea lice removal by cleaner fish in salmon aquaculture: a review of the evidence base
Overton, Kathy; Barrett, Luke; Oppedal, Frode; Kristiansen, Tore S; Dempster, Timothy David (Peer reviewed; Journal article, 2020) -
Snorkel sea-cage technology decreases salmon louse infestation by 75% in a full-cycle commercial test
Geitung, Lena; Oppedal, Frode; Stien, Lars Helge; Dempster, Timothy David; Karlsbakk, Egil; Nola, Velimir; Wright, Daniel William (Journal article; Peer reviewed, 2019)Methods to prevent parasite infestations in farmed fish are becoming widespread, yet tests of their effectiveness often lack commercial relevance and statistical power, which may lead to technology misuse. Here, we examined ... -
'Snorkel' sea lice barrier technology reduces sea lice loads on harvest-sized Atlantic salmon with minimal welfare impacts
Stien, Lars Helge; Dempster, Timothy David; Bui, Samantha; Glaropoulos, Alexis; Fosseidengen, Jan Erik; Wright, Daniel W.; Oppedal, Frode (Journal article; Peer reviewed, 2016-02-13)The infestation of farmed Atlantic salmon (Salmo salar) by ectoparasitic sea lice (Lepeophtheirus salmonis) presents a need for new approaches to parasite control. One option is the use of ‘snorkel’ sea lice barrier ... -
Surface environment modification in Atlantic salmon sea-cages: Effects on amoebic gill disease, salmon lice, growth and welfare
Wright, Daniel William; Geitung, Lena; Karlsbakk, Egil; Stien, Lars Helge; Dempster, Timothy David; Oldham, Tina; Nola, Velimir; Oppedal, Frode (Journal article; Peer reviewed, 2018)Surface environment modification is a potential parasite control strategy in Atlantic salmon sea-cage farming. For instance, a temporary low salinity surface layer in commercial-scale snorkel sea-cages has coincided with ...