Effect of cleaner fish on sea lice in Norwegian salmon aquaculture: a national scale data analysis

Barrett, Luke T.; Overton, Kathy; Stien, Lars Helge; Oppedal, Frode; Dempster, Tim

doi:10.1016/j.ijpara.2019.12.005

Cited by 43 publications

(30 citation statements)

References 36 publications

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“…Future studies could assess if IgT-B cells contribute to a putative ocular specific immune response to infection by pathogens. A recent national level analysis of cleaner fish use on salmon farms in Norway concluded that, while benefits of the use of cleaner fish on some farms is clear, suboptimal usage of cleaner fish remains in some settings (74). Our results raise the possibility that pathogen mediated visual disruption might impact cleaner fish visual health in such settings.…”

Section: Discussionmentioning

confidence: 64%

CD10+ Cells and IgM in Pathogen Response in Lumpfish (Cyclopterus lumpus) Eye Tissues

et al. 2020

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Lumpfish (Cyclopterus lumpus), a North Atlantic “cleaner“ fish, is utilized to biocontrol salmon louse (Lepeophtheirus salmonis) in Atlantic salmon (Salmo salar) farms. Lumpfish require excellent vision to scan for and eat louse on salmon skin. The lumpfish eye immune response to infectious diseases has not been explored. We examined the ocular response to a natural parasite infection in wild lumpfish and to an experimental bacterial infection in cultured lumpfish. Cysts associated with natural myxozoan infection in the ocular scleral cartilage of wild adult lumpfish harbored cells expressing cluster of differentiation 10 (CD10) and immunoglobulin M (IgM). Experimental Vibrio anguillarum infection, which led to exophthalmos and disorganization of the retinal tissues was associated with disruption of normal CD10 expression, CD10+ cellular infiltration and IgM expression. We further describe the lumpfish CD10 orthologue and characterize the lumpfish scleral skeleton in the context of myxozoan scleral cysts. We propose that lumpfish develop an intraocular response to pathogens, exemplified herein by myxozoan and V. anguillarum infection involving novel CD10+ cells and IgM+ cells to contain and mitigate damage to eye structures. This work is the first demonstration of CD10 and IgM expressing cells in a novel ocular immune system component in response to disease in a teleost.

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Section: Discussionmentioning

confidence: 64%

CD10+ Cells and IgM in Pathogen Response in Lumpfish (Cyclopterus lumpus) Eye Tissues

et al. 2020

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“…2020; Barrett et al . 2020a) is sufficient to justify their poor welfare in commercial sea cages (Nilsen et al . 2014; Hvas et al .…”

Section: Introductionmentioning

confidence: 99%

Prevention not cure: a review of methods to avoid sea lice infestations in salmon aquaculture

Barrett

Oppedal

Robinson

et al. 2020

Reviews in Aquaculture

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The Atlantic salmon aquaculture industry still struggles with ectoparasitic sea lice despite decades of research and development invested into louse removal methods. In contrast, methods to prevent infestations before they occur have received relatively little research effort, yet may offer key benefits over treatment‐focused methods. Here, we summarise the range of potential and existing preventative methods, conduct a meta‐analysis of studies trialling the efficacy of existing preventative methods and discuss the rationale for a shift to the prevention‐focused louse management paradigm. Barrier technologies that minimise host–parasite encounter rates provide the greatest protection against lice, with a weighted median 76% reduction in infestation density in cages with plankton mesh ‘snorkels’ or ‘skirts’, and up to a 100% reduction for fully enclosed cages. Other methods such as geographic spatiotemporal management, manipulation of swimming depth, functional feeds, repellents and host cue masking can drive smaller reductions that may be additive when used in combination with barrier technologies. Finally, ongoing development of louse‐resistant salmon lineages may lead to long‐term improvements if genetic gain is maintained, while the development of an effective vaccine remains a key target. Preventative methods emphasise host resistance traits while simultaneously reducing host–parasite encounters. Effective implementation has the potential to dramatically reduce the need for delousing and thus improve fish welfare, productivity and sustainability in louse‐prone salmon farming regions.

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“…2020; Barrett et al . 2020b). A recent analysis of more than 500 farms in Norway suggested that the louse removal effects of cleaner fish are patchy in space and time (Barrett et al .…”

Section: Cleaner Fishmentioning

confidence: 99%

“…A recent analysis of more than 500 farms in Norway suggested that the louse removal effects of cleaner fish are patchy in space and time (Barrett et al . 2020b). Whether cleaner fish efficacy has declined over three decades of use is unknown, due to a shortage of data collected on efficacy across this period.…”

Section: Cleaner Fishmentioning

confidence: 99%

Evolution of salmon lice in response to management strategies: a review

Coates

Phillips

Bui

et al. 2021

Reviews in Aquaculture

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Ectoparasitic salmon lice (Lepeophtheirus salmonis) present a major challenge to Atlantic salmon (Salmo salar) aquaculture. The demand for effective louse control has produced diverse management strategies. These strategies essentially impose novel selection pressures on parasite populations, driving the evolution of resistance. Here we assess the potential for salmon lice to adapt to current prevention and control methods. Lice have evolved resistance to at least four of five chemical therapeutants, and use of these chemicals has declined significantly in recent years. The industry has shifted to alternative non-chemical approaches, yet lice may adapt to these as well. Early research suggests that phenotypic variation exists in the louse population upon which non-chemical selection pressures could act and that this variation may have a genetic basis. From the existing evidence, as well as an examination of evolutionary processes in other relevant parasite and pest systems, we conclude that the evolution of non-chemical resistance is an emergent concern that must be considered by the industry. We recommend areas for focused research to better assess this risk. It is also important to determine whether phenotypic shifts in response to non-chemical selection may shift the ecological niche of the parasite, as this may have cascading effects on wild salmon populations. We also recommend further research to identify strategy combinations that have antagonistic selective effects that slow louse evolution and those with synergistic effects that should be avoided. Greater understanding of evolutionary processes can inform aquaculture policies that counteract the rise of resistant parasite populations.

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Effect of cleaner fish on sea lice in Norwegian salmon aquaculture: a national scale data analysis

Cited by 43 publications

References 36 publications

CD10+ Cells and IgM in Pathogen Response in Lumpfish (Cyclopterus lumpus) Eye Tissues

CD10+ Cells and IgM in Pathogen Response in Lumpfish (Cyclopterus lumpus) Eye Tissues

Prevention not cure: a review of methods to avoid sea lice infestations in salmon aquaculture

Evolution of salmon lice in response to management strategies: a review

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