Cessation of a salmon decline with control of parasites

• Published in: Ecological Applications
• Main Authors: Peacock, Stephanie J., Krkošek, Martin, Proboszcz, Stan, Orr, Craig, Lewis, Mark A.
• Other Authors: University of Alberta, Edmonton, Canada, University of Otago, Dunedin, New Zealand, Salmon Coast Field Station, British Columbia, Simoom Sound, Canada, Watershed Watch Salmon Society, , Canada
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: Wiley 2013
• Subjects: Adaptive management; Aquaculture; Host-parasite; Lepeophtheirus salmonis; Migration; Pacific Canada; Parasiticide; Salmon; Sea lice; Oncorhynchus gorbuscha; Pink salmon
• Online Access: http://hdl.handle.net/10754/597747; https://doi.org/10.1890/12-0519.1

The resilience of coastal social-ecological systems may depend on adaptive responses to aquaculture disease outbreaks that can threaten wild and farm fish. A nine-year study of parasitic sea lice (Lepeophtheirus salmonis) and pink salmon (Oncorhynchus gorbuscha) from Pacific Canada indicates that adaptive changes in parasite management on salmon farms have yielded positive conservation outcomes. After four years of sea lice epizootics and wild salmon population decline, parasiticide application on salmon farms was adapted to the timing of wild salmon migrations. Winter treatment of farm fish with parasiticides, prior to the out-migration of wild juvenile salmon, has reduced epizootics of wild salmon without significantly increasing the annual number of treatments. Levels of parasites on wild juvenile salmon significantly influence the growth rate of affected salmon populations, suggesting that these changes in management have had positive outcomes for wild salmon populations. These adaptive changes have not occurred through formal adaptive management, but rather, through multi-stakeholder processes arising from a contentious scientific and public debate. Despite the apparent success of parasite control on salmon farms in the study region, there remain concerns about the long-term sustainability of this approach because of the unknown ecological effects of parasticides and the potential for parasite resistance to chemical treatments. © 2013 by the Ecological Society of America. We thank two anonymous referees whose comments greatlyimproved the manuscript. We are grateful to those at DFO whogenerated and shared escapement and catch data, A. Mortonfor providing the weekly monitoring data, and the manyindividuals who contributed to the sea lice fieldwork: E. Nelson,J. Volpe, S. Rogers, A. Park, D. Stabel, H. Ford, A. Yeomans-Routledge, M. Paleczny, G. Garramone, and S. Durkee. We arealso grateful to A. Ibell and L. Rogers for assembling andpreparing the database. This work was supported by fundingfrom the ...