Synthetic pyrethroids have been widely used in Chile to control the sea lice Caligus rogercresseyi, a major ectoparasite of farmed salmon. Although resistance of C. rogercresseyi to pyrethroids has been reported in Chile, there is no information regarding the geographic extent of this problem. In this study we explored the spatial and temporal variation of C. rogercresseyi's response to pyrethroids in Chile from 2012 to 2013. We modeled lice abundance one week after treatment with a linear mixed-effects regression, and then we performed spatial and spatio-temporal cluster analyses on farm-level effects and on treatment-level residuals, respectively. Results indicate there were two areas where the post-treatment lice counts were significantly higher than in the rest of the study area. These spatial clusters remained even once we adjusted for environmental and management predictors, suggesting unmeasured factors (e.g. resistance) were causing the clustering. Further investigation should be carried out to confirm this hypothesis.
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http://dx.doi.org/10.1016/j.sste.2018.04.004 | DOI Listing |
J Aquat Anim Health
December 2024
Department of Health Management and Centre for Veterinary Epidemiological Research, Atlantic Veterinary College, University of Prince Edward Island, Charlottetown, Prince Edward Island, Canada.
Objective: The primary objective was to construct a time series model for the abundance of the adult female (AF) sea lice Lepeophtheirus salmonis in Atlantic Salmon Salmo salar farms in the Bay of Fundy, New Brunswick, Canada, for the period 2016-2021 and to illustrate its short-term predictive capabilities.
Methods: Sea lice are routinely counted for monitoring purposes, and these data are recorded in the Fish-iTrends database. A multivariable autoregressive linear mixed-effects model (second-order autoregressive structure) was generated with the outcome of the abundance of AF sea lice and included treatments, infestation pressures (a measure that represents the dose of exposure of sea louse parasitic stages to potential fish hosts) within sites (internal) and among sites (external), and other predictors.
Sci Rep
December 2024
Department of Health Management, Atlantic Veterinary College, University of Prince Edward Island, Charlottetown, PEI, C1A 4P3, Canada.
Monitoring mortality is an essential strategy for fish health management. Commercial marine finfish sites in British Columbia, Canada, are required to report mortality events (MEs) to Fisheries and Oceans Canada (DFO), which makes these data publicly available. This study aimed to analyze the spatial and temporal patterns of ME composition and total MEs.
View Article and Find Full Text PDFPrev Vet Med
December 2024
Norwegian Veterinary Institute, Elizabeth Stephansens vei 1, Ås N-1433, Norway.
Salmon lice (Lepeophtheirus salmonis) are parasites on salmonid fish and a density-dependent constraint to the sustainable farming of salmonids in open net pens. To control the parasites, fish farmers in Norway are required to count the number of salmon lice in different developmental stages on a subset of the fish each week. Furthermore, they must ensure that the number of adult female lice per fish does not increase beyond a specified threshold level.
View Article and Find Full Text PDFBMC Genomics
December 2024
Institute of Aquaculture, University of Stirling, Stirling, Scotland, UK.
Background: The salmon louse (Lepeophtheirus salmonis) is a parasite of wild and farmed salmonid fish, causing huge economic damage to the commercial farming of Atlantic salmon (Salmo salar) in the northern hemisphere. The avermectin emamectin benzoate (EMB) is widely used for salmon delousing. While resistance to EMB is widespread in Atlantic populations of L.
View Article and Find Full Text PDFIn areas with high densities of salmon farming, spillover of the ectoparasitic salmon louse Lepeophtheirus salmonis poses a major threat to wild anadromous salmonids. By combining experimentally salmon louse infestation (mean ± standard deviation = 0.25 ± 0.
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