Gone with the flow: current velocities mediate parasitic infestation of an aquatic host

Samsing, Francisca; Solstorm, David; Oppedal, Frode; Solstorm, Frida; Dempster, Tim

doi:10.1016/j.ijpara.2015.03.006

Cited by 43 publications

(27 citation statements)

References 39 publications

(46 reference statements)

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“…Specifically, at low-exposure sites, the infection rate tends to increase faster with the total number of salmon than at high-exposure sites. One final point to note is that current speed can strongly influence the attachment of sea lice to fish (Samsing et al 2015). Thus the effect of exposure on infection rates is not solely through population dynamics at different sites, but also directly acts on the infestation process.…”

Section: Discussionmentioning

confidence: 99%

Effect of exposure on salmon lice Lepeophtheirus salmonis population dynamics in Faroese salmon farms

Patursson¹,

Simonsen²,

Visser³

et al. 2017

Aquacult. Environ. Interact.

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We assessed variations in salmon lice Lepeophtheirus salmonis population dynamics in Faroese salmon farms in relationship to their physical exposure to local circulation patterns and flushing with adjacent waters. Factors used in this study to quantify physical exposure are estimates of the freshwater exchange rate, the tidal exchange rate and dispersion by tidal currents. Salmon farms were ranked according to the rate of increase in the average numbers of salmon lice per fish. In a multiple linear regression, physical exposure together with temperature were shown to have a significant effect on the rate of lice infection. The sites with low exposure revealed higher rates of self-infection and internally driven outbreak dynamics, while high-exposure sites showed lower rates of self-infection, tending towards externally driven outbreak dynamics. The lowexposure sites also appeared to have a lower threshold of salmon stocking numbers for outbreaks of infection. The study presents a simple method of characterizing salmon farming fjords in terms of their different exposure levels and how they relate to potential self-infection at these sites.

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Section: Discussionmentioning

confidence: 99%

Effect of exposure on salmon lice Lepeophtheirus salmonis population dynamics in Faroese salmon farms

Patursson¹,

Simonsen²,

Visser³

et al. 2017

Aquacult. Environ. Interact.

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“…; Samsing et al . ). Although the swimming speed of salmon is driven by internal preferences and current velocity (Drenner et al .…”

Section: Alternative Prevention and Control Methods For The Future Toolboxmentioning

confidence: 97%

Behaviour in the toolbox to outsmart parasites and improve fish welfare in aquaculture

Bui

Oppedal

Sievers

et al. 2017

Reviews in Aquaculture

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Host behaviour can prevent infection and moderate the fitness of parasites. Antiparasite behaviours are prevalent in many host–parasite systems and occur over fine or broad scales. With global growth in aquaculture production and the associated proliferation of parasites in farming systems, the behaviour of the fish being farmed has seldom been investigated in relation to parasites. Epidemics and outbreaks of parasites are prevalent in most aquaculture systems, and behaviour could be harnessed in concert with current methods to prevent and control parasites and pathogens. However, this requires a systematic understanding of the behaviours of hosts, their capacity for resistance and their interaction with the environment and the parasite. Herein, we present evidence for how behaviour could be used in aquaculture, and discuss the possibility for behaviour to be used in aquaculture as (i) an indicator of welfare status, (ii) a tool in prevention or control and (iii) to maintain or improve welfare. We apply this framework to a case study of a highly problematic parasite, the salmon louse (Lepeophtheirus salmonis), on farmed Atlantic salmon (Salmo salar). We present the current state of the system, and the drawbacks of current control or prevention methods. We synergise current knowledge on host behaviours and show how behaviour could be incorporated into current and new approaches for prevention and control. Through this first evaluation of the possibilities behaviour presents in disease management, we aim to facilitate a shift in the current disease control paradigm from reactive‐based post‐infection control to pre‐infection prevention approaches.

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“…It has been estimated that under certain conditions, the planktonic larvae can spread more than 100 km before they need to attach to a host (Asplin et al 2011. Recent experiments at different current velocities have shown that attachment probability of salmon lice during an encounter with a potential host likely is dependent on the swimming speed of the host (Samsing et al 2015) Modelling from salmon farms in Norway has shown how salmon lice spread between farms and has revealed that the infestation pressure among farms increases with density of fish and temperature (Jansen et al 2012). Other studies have evaluated effects of environmental variables on salmon lice dynamics in farmed salmonids (e.g.…”

Section: Introductionmentioning

confidence: 99%

Statistical and ecological challenges of monitoring parasitic salmon lice infestations in wild salmonid fish stocks

Helland¹,

Uglem²,

Jansen³

et al. 2015

Aquacult. Environ. Interact.

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Ecological monitoring programmes should provide precise data to inform management, but the data quality is often limited by methodological challenges and the need for cost-effective sampling. Parasite infestations are particularly challenging to monitor due to complex interactions among hosts, parasites and the environment. In Norway, salmon lice infestations on wild salmonid fish have been monitored since 1992 to survey the potential transmission between farmed and wild salmonids. Here, we compared spatiotemporal variation in salmon lice levels with variations in local fjord conditions, including salinity, temperature and infestation pressure from salmon farms (measured as mean abundance of mature female lice × number of farmed fish). We tested 3 different measures of infestation with different statistical properties. Our results confirm that, even after correcting for temperature and salinity effects, infestation pressure from salmon farms significantly increases the probability of lice infestation in wild salmonids. The probability of infestation increases with fish body length, salmon farm infestation pressure and tem perature, and decreases with increasing freshwater influence. Furthermore, we found a significant interaction between temperature and infestation pressure from salmon farms. When the infestation pressure from farms is low, temperature has a strong increasing effect on the probability of infestation, but as the infestation pressure from farms increases, temperature gradually becomes less important. The exact results vary somewhat depending on the measure of lice infestations used, but the same trend can be seen in all models. We discuss the statistical and biological complexities that make monitoring of salmon lice in wild populations challenging.Variation in salmon lice levels on wild salmonids have been monitored along the entire Norwegian coast.Photo: Bengt Finstad. Map: Ingeborg P. Helland

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Gone with the flow: current velocities mediate parasitic infestation of an aquatic host

Cited by 43 publications

References 39 publications

Effect of exposure on salmon lice Lepeophtheirus salmonis population dynamics in Faroese salmon farms

Effect of exposure on salmon lice Lepeophtheirus salmonis population dynamics in Faroese salmon farms

Behaviour in the toolbox to outsmart parasites and improve fish welfare in aquaculture

Statistical and ecological challenges of monitoring parasitic salmon lice infestations in wild salmonid fish stocks

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