Spatial patterns of sea lice infection among wild and captive salmon in western Canada
Parasite transmission between captive and wild fish is mediated by spatial, abiotic, biotic, and management factors. More effective population management and conservation strategies can result from multivariable assessments of factors associated with spatial dynamics of parasite spillover.
Our study characterised spatial patterns of sea lice (Lepeophtheirus salmonis,Caligus clemensi) infection on out-migrating chum (Oncorhynchus keta) and pink (O. gorbuscha) salmon in an area with Atlantic salmon (Salmo salar) farming.
A multivariable statistical model for sea louse parasitism of out-migrating chum and pink salmon was developed from 166,316 wild salmon sampled in the Broughton Archipelago, British Columbia, Canada from 2003 to 2012. We assessed for factors hypothesized to influence sea lice infection levels, at the non-motile life stage, including spatial scales of infection sources.
Fish length, sampling year and method were strong explanatory factors. Infection was greatest in higher salinity water. Farmed and wild juvenile salmon infection levels were correlated, on average, within 30 km. Except for 2004, sea lice infection on farms were typically well below the regulatory level (3 motiles per fish). Average intensity of non-motile infections observed on the wild fish were 6.36 (SD = 9.98) in 2004 compared to 1.66 (SD = 1.25) for the other years.
Accuracy of future model estimates will benefit by including hydrodynamic data accounting for anisotropic spread of sea lice from sources. Multivariable statistical modelling over long time series data strengthens understanding of factors impacting wild juvenile salmon infection levels and informs spatial patterns of aquatic epidemiology.
KeywordsAtlantic salmon aquaculture British Columbia Caligus clemensi Lepeophtheirus salmonis Pacific salmon Sea lice Spatial–temporal modeling
- Anderson RM, May RM (1991) Infectious disease of humans: dynamics and control, 1st edn. Oxford University Press, New York, p 757Google Scholar
- Beamish RJ, Jones S, Neville C-E, Sweeting R, Karreman G, Saksida S, Gordon E (2006) Exceptional marine survival of pink salmon that entered the marine environment in 2003 suggests that farmed Atlantic salmon and Pacific salmon can coexist successfully in a marine ecosystem on the Pacific coast of Canada. ICES J Mar Sci 63:1326–1337CrossRefGoogle Scholar
- Brauner CJ, Sackville M, Gallagher Z, Tang S, Nendick L, Farrell AP (2012) Physiological consequences of the salmon louse (Lepeophtheirus salmonis) on juvenile pink salmon (Oncorhynchus gorbuscha): implications for wild salmon ecology and management, and for salmon aquaculture. Phil Trans R Soc B 367:1770–1779CrossRefPubMedCentralPubMedGoogle Scholar
- Brooks KM (2005) The effects of water temperature, salinity, and currents on the survival and distribution of the infective copepodid stage of sea lice (Lepeophtheirus Salmonis) originating on Atlantic salmon farms in the Broughton Archipelago of British Columbia, Canada. Rev Fish Sci 13:177–204CrossRefGoogle Scholar
- Burnham KP, Anderson DR (2002) Model selection and multimodel inference: a practical information-theoretic approach, 2nd edn. Springer, New York, p 488Google Scholar
- Fast MD, Ross NW, Mustafa A, Sims DE, Johnson SC, Conboy GA, Speare DJ, Johnson G, Burka JF (2002) Susceptibility of rainbow trout Oncorhynchus mykiss, Atlantic salmon Salmo salar and coho salmon Oncorhynchus kisutch to experimental infection with sea lice Lepeophtheirus salmonis. Dis Aquat Organ 52:57–68CrossRefPubMedGoogle Scholar
- Gustafson LL, Ellis SK, Beattie MJ, Chang BD, Dickey DA, Robinson TL, Marenghi FP, Moffett PJ, Page FH (2007) Hydrographics and the timing of infectious salmon anemia outbreaks among Atlantic salmon (Salmo salar L.) farms in the Quoddy region of Maine, USA and New Brunswick, Canada. Prev Vet Med 78:35–56CrossRefPubMedGoogle Scholar
- Heard WR (1991) Life history of pink salmon (Oncorhynchus gorbuscha). In: Groot C, Margolis L (eds) Pacific Salmon Life Histories, 1st edn. University of British Columbia Press, Vancouver, pp 119–230Google Scholar
- Hosmer DW, Lemeshow S (2004) Applied logistic regression, 2nd edn. Wiley, New York, p 392Google Scholar
- Jones SRM, Prosperi-Porta G, Kim E, Callow P, Hargreaves NB (2006a) The occurrence of Lepeophtheirus salmonis and Caligus clemensi (Copepoda: Caligidae) on three-spine stickleback Gasterosteus aculeatus in coastal British Columbia. J Parasitol 92:473–480Google Scholar
- Jones SRM, Wosniok W, Hargreaves NB (2006b) The salmon louse Lepeophtheirus salmonis on salmonid and non-salmonid fishes in British Columbia. In: Proceedings of the 11th international symposium on veterinary epidemiology and economics.Google Scholar
- Krkosek M, Revie CW, Gargan PG, Skilbrei OT, Finstad B, Todd CD (2013) Impact of parasites on salmon recruitment in the Northeast Atlantic Ocean. Proc R Soc B Biol Sci 280:2012–2359Google Scholar
- Morton AB, Williams R (2003) First report of a sea louse, Lepeophtheirus salmonis, infestation on juvenile pink salmon, Oncorhynchus gorbuscha, in nearshore habitat. Can Field Nat 117:634–641Google Scholar
- Moss JH, Murphy JM, Farley EV, Eisner LB, Andrews AG (2009) Juvenile pink and chum salmon distribution, diet, and growth in the northern Bering and Chukchi Seas. North Pac Anadromous Fish Comm 5:191–196Google Scholar
- Okabe A, Boots B, Sugihara K, Chiu SN (2000) Spatial tessellations––concepts and applications of Voronoi diagrams, 2nd edn. Wiley, Chichester, p 696Google Scholar
- R Development Core Team (2012) R: a language and environment for statistical computing. R Foundation for Statistical Computing, Vienna. ISBN 3-900051-07-0. http://www.R-project.org/
- Salo EO (1991) Life history of chum salmon (Oncorhynchus keta). In: Groot C, Margolis L (eds) Pacific salmon life histories, 1st edn. University of British Columbia Press, Vancouver, pp 231–309Google Scholar
- Stucchi DJ, Guo M, Foreman MGG, Czajko P, Galbraith M, Mackas DL, Gillibrand PA (2011) Modeling sea lice production and concentrations in the Broughton Archipelago, British Columbia. In: Jones S, Beamish R (eds) Salmon lice: an integrated approach to understanding parasite abundance and distribution, 1st edn. Wiley, Chichester, pp 117–150CrossRefGoogle Scholar
- Sutherland BJG, Jantzen SG, Sanderson DS, Koop BF, Jones SRM (2011) Differentiating size-dependent responses of juvenile pink salmon (Oncorhynchus gorbuscha) to sea lice (Lepeophtheirus salmonis) infections. Comp Biochem Physiol 6:213–223Google Scholar
- van Etten J (2012) gdistance: distances and routes on geographical grids. R package version 1.1–4. http://CRAN.Rproject.org/package=gdistance