Sterilization of sea lice eggs with ultraviolet C light: towards a new preventative technique for aquaculture

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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“…2018), direct current electricity (Bredahl 2014) and irradiation with short‐wavelength light (Barrett et al . 2020b; Barrett et al . 2020c).…”

Section: What Preventative Methods Are Available?mentioning

confidence: 99%

“…2018; Barrett et al . 2020b; Barrett et al . 2020c), but it is currently unclear whether any such methods can be effective at commercial scale.…”

Section: What Preventative Methods Are Available?mentioning

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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“…3,38,39 The rate of killing for sea lice eggs was 5% at a UV dose of 0.008 J cm −2 , but increased to 95% when the UV dose was 0.09 J cm −2 . 38 Similarly, a UV dose of 2.69 × 10 5 μWs cm −2 did not kill theronts of C. irritans but the UV dose became lethal it was above 2.88 × 10 5 μWs cm −2 . 3 In this study, the survival rate of protomonts and tomonts of C. irritans decreased significantly with an increase in UV dose.…”

Section: Discussionmentioning

confidence: 99%

Sustainable development of factory aquaculture through automation of ultraviolet parasiticide for the prevention and control of cryptocaryoniasis

Zhou

Kang

et al. 2022

Pest Management Science

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Background Cryptocaryon irritans infestations on marine teleosts are a considerable burden on factory mariculture. Ultraviolet (UV) light can kill C. irritans under laboratory conditions. However, a rational method for using UV in factory aquaculture to control cryptocaryoniasis has not been developed. This study focused on evaluating the killing effect of UV on protomonts and tomonts of C. irritans and established an automatic UV parasiticide device for the prevention and control of cryptocaryoniasis in marine teleosts. Results The survival rate of protomonts and tomonts decreased with an increase in the UV irradiation dose. All the protomonts and tomonts died within 14 and 24 min, respectively. The lowest UV lethal doses of protomonts and tomonts of C. irritans were 2.0 × 106 and 3.5 × 106 μWs cm−2, respectively. Exposure of protomonts and tomonts to lethal doses of UV radiation led to shrinkage and severe dissolution of the protoplasm, causing abnormal development of cells. The survival rate of artificially infected Larimichthys crocea (treatment group, group A) was 83.33% at the end of the test (day 14) after disinfection using the automatic UV parasiticide device, whereas that of the control group (group C) was 90.00% (p < 0.05). However, all artificially infected L. crocea without disinfection using the automatic UV parasiticide device (untreated group, group B) died on day 8. Conclusion The automation of traditional physical methods conforms to the sustainable development of aquaculture and provides a theoretical reference for the prevention and control of cryptocaryoniasis in mariculture. © 2022 Society of Chemical Industry.

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“…e = ED 63 ) while with the Gompertz function the reduction accrued at a dose equal to e is 36.6%, that is, e ≈ ED 37 35 . However, the parameter e has erroneously been interpreted as ED 50 in several studies despite the fact that an asymmetrical model has been fitted to dose–response data 20,36–39 …”

Section: Common Errorsmentioning

confidence: 99%

“…35 However, the parameter e has erroneously been interpreted as ED 50 in several studies despite the fact that an asymmetrical model has been fitted to dose-response data. 20,[36][37][38][39] 3.8 Solution to Error #4: Fitting symmetrical models or calculating absolute ED 50 There is no global recipe as to whether a symmetrical or asymmetrical model should be used but rather the choice of model should be determined by data and the goodness of fit. Statistical tests such as the F-test, likelihood ratio test, AIC, and Bayesian Information Criterion (BIC) can be used for model selection.…”

Section: Error #4mentioning

confidence: 99%

Perspective: common errors in dose–response analysis and how to avoid them

Keshtkar

Kudsk

Mesgaran

2021

Pest Management Science

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Dose–response experiments are conducted to determine the toxicity of chemicals on organisms. The relationship between dose and response is described by different statistical models. The four‐parameter log‐logistic model is widely used in pesticide sciences to derive biologically relevant parameters such as ED50 and resistance index (RI). However, there are some common errors associated with the calculation of ED50 and RI that can lead to erroneous conclusions. Here we discuss five common errors and propose guidance to avoid them. We suggest (i) all response curves must be fitted simultaneously to allow for proper comparison of parameters across curves, (ii) in the case of nonparallel curves absolute ED50 must be used instead of relative ED50, (iii) standard errors or confidence intervals of the parameters must be reported, (iv) the e parameter in asymmetrical models is not equal to ED50 and hence absolute ED50 must be estimated, and (v) when the four‐parameter log‐logistic model returns a negative value for the lower asymptote, which is biologically meaningless in most cases, the model should be reduced to its three‐parameter version or other types of model should be applied. The mixed‐effects model and the meta‐analytic approach are suggested as appropriate to average the parameters across repeated dose–response experiments. © 2021 Society of Chemical Industry

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Sterilization of sea lice eggs with ultraviolet C light: towards a new preventative technique for aquaculture

Cited by 8 publications

References 31 publications

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

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

Sustainable development of factory aquaculture through automation of ultraviolet parasiticide for the prevention and control of cryptocaryoniasis

Perspective: common errors in dose–response analysis and how to avoid them

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