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Godwin SC, Krkošek M, Reynolds JD, Bateman AW. Bias in self-reported parasite data from the salmon farming industry. ECOLOGICAL APPLICATIONS : A PUBLICATION OF THE ECOLOGICAL SOCIETY OF AMERICA 2021; 31:e02226. [PMID: 32896013 DOI: 10.1002/eap.2226] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/22/2020] [Revised: 07/01/2020] [Accepted: 07/20/2020] [Indexed: 06/11/2023]
Abstract
Many industries are required to monitor themselves in meeting regulatory policies intended to protect the environment. Self-reporting of environmental performance can place the cost of monitoring on companies rather than taxpayers, but there are obvious risks of bias, often addressed through external audits or inspections. Surprisingly, there have been relatively few empirical analyses of bias in industry self-reported data. Here, we test for bias in reporting of environmental compliance data using a unique data set from Canadian salmon farms, where companies monitor the number of parasitic sea lice on fish in open sea pens, in order to minimize impacts on wild fish in surrounding waters. We fit a hierarchical population-dynamics model to these sea-louse count data using a Bayesian approach. We found that the industry's monthly counts of two sea-louse species, Caligus clemensi and Lepeophtheirus salmonis, increased by a factor of 1.95 (95% credible interval: 1.57, 2.42) and 1.18 (1.06, 1.31), respectively, in months when counts were audited by the federal fisheries department. Consequently, industry sea-louse counts are less likely to trigger costly but mandated delousing treatments intended to avoid sea-louse epidemics in wild juvenile salmon. These results highlight the potential for combining external audits of industry self-reported data with analyses of their reporting to maintain compliance with regulations, achieve intended conservation goals, and build public confidence in the process.
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Affiliation(s)
- Sean C Godwin
- Earth to Ocean Research Group, Department of Biological Sciences, Simon Fraser University, 8888 University Drive, Burnaby, British Columbia, V5A 1S6, Canada
- Department of Biology, Dalhousie University, 1355 Oxford Street, Halifax, Nova Scotia, B3H 4R2, Canada
| | - Martin Krkošek
- Department of Ecology and Evolutionary Biology, University of Toronto, 25 Willcocks Street, Toronto, Ontario, M5S 3B2, Canada
- Salmon Coast Field Station, General Delivery, Simoom Sound, British Columbia, V0P 1S0, Canada
| | - John D Reynolds
- Earth to Ocean Research Group, Department of Biological Sciences, Simon Fraser University, 8888 University Drive, Burnaby, British Columbia, V5A 1S6, Canada
| | - Andrew W Bateman
- Salmon Coast Field Station, General Delivery, Simoom Sound, British Columbia, V0P 1S0, Canada
- Department of Geography, University of Victoria, 3800 Finnerty Road, Victoria, British Columbia, V8P 5C2, Canada
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2
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Bateman AW, Peacock SJ, Krkošek M, Lewis MA. Migratory hosts can maintain the high-dose/refuge effect in a structured host-parasite system: The case of sea lice and salmon. Evol Appl 2020; 13:2521-2535. [PMID: 33294006 PMCID: PMC7691465 DOI: 10.1111/eva.12984] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2019] [Revised: 04/14/2020] [Accepted: 04/15/2020] [Indexed: 01/13/2023] Open
Abstract
Migration can reduce parasite burdens in migratory hosts, but it connects populations and can drive disease dynamics in domestic species. Farmed salmon are infested by sea louse parasites, often carried by migratory wild salmonids, resulting in a costly problem for industry and risk to wild populations when farms amplify louse numbers. Chemical treatment can control lice, but resistance has evolved in many salmon-farming regions. Resistance has, however, been slow to evolve in the north-east Pacific Ocean, where large wild-salmon populations harbour large sea louse populations. Using a mathematical model of host-macroparasite dynamics, we explored the roles of domestic, wild oceanic and connective migratory host populations in maintaining treatment susceptibility in associated sea lice. Our results show that a large wild salmon population, unexposed to direct infestation by lice from farms; high levels of on-farm treatment; and a healthy migratory host population are all critical to slowing or stopping the evolution of treatment resistance. Our results reproduce the "high-dose/refuge effect," from the agricultural literature, with the added requirement of a migratory host population to maintain treatment susceptibility. This work highlights the role that migratory hosts may play in shared wildlife/livestock disease, where evolution can occur in ecological time.
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Affiliation(s)
- Andrew W. Bateman
- Pacific Salmon FoundationVancouverBCCanada
- Salmon Coast Field StationSimoom SoundBCCanada
| | - Stephanie J. Peacock
- Salmon Coast Field StationSimoom SoundBCCanada
- Department of Biological SciencesUniversity of CalgaryCalgaryABCanada
| | - Martin Krkošek
- Salmon Coast Field StationSimoom SoundBCCanada
- Department of Ecology and Evolutionary BiologyUniversity of TorontoTorontoONCanada
| | - Mark A. Lewis
- Department of Biological SciencesUniversity of AlbertaEdmontonABCanada
- Department of Mathematical and Statistical SciencesUniversity of AlbertaEdmontonABCanada
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3
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Julinta RB, Abraham TJ, Roy A, Singha J, Bardhan A, Sar TK, Patil PK, Kumar KA. Safety of emamectin benzoate administered in feed to Nile tilapia Oreochromis niloticus (L.). ENVIRONMENTAL TOXICOLOGY AND PHARMACOLOGY 2020; 75:103348. [PMID: 32032933 DOI: 10.1016/j.etap.2020.103348] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/16/2019] [Revised: 01/25/2020] [Accepted: 01/29/2020] [Indexed: 06/10/2023]
Abstract
Emamectin benzoate (EB) premix top-coated onto feed is extensively used to treat ectoparasitic crustacean infestations in aquaculture. This study evaluated the safety of EB-dosing in Nile tilapia Oreochromis niloticus at the recommended dose and dosage of 50 μg/kg biomass/day for 7 consecutive days (1X) and compared with control and 10 times the recommended dose (10X). Depletion of EB-residues in the edible muscle of 1X-dosed Nile tilapia was also studied. Mortality, behavioural changes, feed consumption, biomass, EB-residue depletion, and histopathological alterations in the kidney, liver and intestine were determined at slated intervals. Significant dose-dependent reduction in feed intake and biomass and insignificant mortalities were noted in 1X and 10X EB-dosed fish. In 1X EB-dosed fish muscle, the residues peaked on day 7 EB-dosing (9.72 ng/g) and decreased subsequently. Nevertheless, the residue levels were within the acceptable limit of the European Commission and the Canadian Food Inspection Agency even during the EB-dosing period. Histologically, tubule degeneration in the kidney, mild glycogen vacuolation in the liver, and loss of absorptive vacuoles, inflammation and disintegration of the epithelial layer in the intestine of Nile tilapia fed the 1X EB-diet were observed. The fish reverted back to their normal functions with time upon termination of oral-EB-dosing. This work contributed scientific data on the safety of EB particularly on the feed intake, growth reduction, mortality, histopathological alterations, and EB-residue levels in the edible tissues of Nile tilapia fed at the recommended dose and dosage, which suggested that EB-therapy might be reasonably risky in a tropical climate.
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Affiliation(s)
- Roy Beryl Julinta
- Department of Aquatic Animal Health, Faculty of Fishery Sciences, West Bengal University of Animal and Fishery Sciences, Chakgaria, Kolkata, 700 094, West Bengal, India
| | - Thangapalam Jawahar Abraham
- Department of Aquatic Animal Health, Faculty of Fishery Sciences, West Bengal University of Animal and Fishery Sciences, Chakgaria, Kolkata, 700 094, West Bengal, India.
| | - Anwesha Roy
- Department of Aquatic Animal Health, Faculty of Fishery Sciences, West Bengal University of Animal and Fishery Sciences, Chakgaria, Kolkata, 700 094, West Bengal, India
| | - Jasmine Singha
- Department of Aquatic Animal Health, Faculty of Fishery Sciences, West Bengal University of Animal and Fishery Sciences, Chakgaria, Kolkata, 700 094, West Bengal, India
| | - Avishek Bardhan
- Department of Aquatic Animal Health, Faculty of Fishery Sciences, West Bengal University of Animal and Fishery Sciences, Chakgaria, Kolkata, 700 094, West Bengal, India
| | - Tapas Kumar Sar
- Department of Veterinary Pharmacology, Faculty of Veterinary and Animal Sciences, West Bengal University of Animal and Fishery Sciences, Belgachia, Kolkata, 700 037, West Bengal, India
| | - Prasanna Kumar Patil
- Aquatic Animal Health and Environment Division, ICAR-Central Institute of Brackishwater Aquaculture, Raja Annamalai Puram, Chennai, 600 028, Tamil Nadu, India
| | - K Ashok Kumar
- Fish Processing Division, ICAR-Central Institute of Fisheries Technology, Willington Island, Cochin, 682 029, Kerala, India
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Cantrell DL, Rees EE, Vanderstichel R, Grant J, Filgueira R, Revie CW. The Use of Kernel Density Estimation With a Bio-Physical Model Provides a Method to Quantify Connectivity Among Salmon Farms: Spatial Planning and Management With Epidemiological Relevance. Front Vet Sci 2018; 5:269. [PMID: 30425996 PMCID: PMC6218437 DOI: 10.3389/fvets.2018.00269] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2018] [Accepted: 10/08/2018] [Indexed: 01/08/2023] Open
Abstract
Connectivity in an aquatic setting is determined by a combination of hydrodynamic circulation and the biology of the organisms driving linkages. These complex processes can be simulated in coupled biological-physical models. The physical model refers to an underlying circulation model defined by spatially-explicit nodes, often incorporating a particle-tracking model. The particles can then be given biological parameters or behaviors (such as maturity and/or survivability rates, diel vertical migrations, avoidance, or seeking behaviors). The output of the bio-physical models can then be used to quantify connectivity among the nodes emitting and/or receiving the particles. Here we propose a method that makes use of kernel density estimation (KDE) on the output of a particle-tracking model, to quantify the infection or infestation pressure (IP) that each node causes on the surrounding area. Because IP is the product of both exposure time and the concentration of infectious agent particles, using KDE (which also combine elements of time and space), more accurately captures IP. This method is especially useful for those interested in infectious agent networks, a situation where IP is a superior measure of connectivity than the probability of particles from each node reaching other nodes. Here we illustrate the method by modeling the connectivity of salmon farms via sea lice larvae in the Broughton Archipelago, British Columbia, Canada. Analysis revealed evidence of two sub-networks of farms connected via a single farm, and evidence that the highest IP from a given emitting farm was often tens of kilometers or more away from that farm. We also classified farms as net emitters, receivers, or balanced, based on their structural role within the network. By better understanding how these salmon farms are connected to each other via their sea lice larvae, we can effectively focus management efforts to minimize the spread of sea lice between farms, advise on future site locations and coordinated treatment efforts, and minimize any impact of farms on juvenile wild salmon. The method has wide applicability for any system where capturing infectious agent networks can provide useful guidance for management or preventative planning decisions.
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Affiliation(s)
- Danielle L Cantrell
- Department of Health Management, Atlantic Veterinary College, University of Prince Edward Island, Charlottetown, PE, Canada
| | - Erin E Rees
- Department of Health Management, Atlantic Veterinary College, University of Prince Edward Island, Charlottetown, PE, Canada.,Land and Sea Systems Analysis, Granby, QC, Canada
| | - Raphael Vanderstichel
- Department of Health Management, Atlantic Veterinary College, University of Prince Edward Island, Charlottetown, PE, Canada
| | - Jon Grant
- Department of Oceanography, Dalhousie University, Halifax, NS, Canada
| | - Ramón Filgueira
- Marine Affairs Program, Dalhousie University, Halifax, NS, Canada
| | - Crawford W Revie
- Department of Health Management, Atlantic Veterinary College, University of Prince Edward Island, Charlottetown, PE, Canada
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Messmer AM, Leong JS, Rondeau EB, Mueller A, Despins CA, Minkley DR, Kent MP, Lien S, Boyce B, Morrison D, Fast MD, Norman JD, Danzmann RG, Koop BF. A 200K SNP chip reveals a novel Pacific salmon louse genotype linked to differential efficacy of emamectin benzoate. Mar Genomics 2018; 40:45-57. [PMID: 29673959 DOI: 10.1016/j.margen.2018.03.005] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2017] [Revised: 02/28/2018] [Accepted: 03/27/2018] [Indexed: 11/28/2022]
Abstract
Antiparasitic drugs such as emamectin benzoate (EMB) are relied upon to reduce the parasite load, particularly of the sea louse Lepeophtheirus salmonis, on farmed salmon. The decline in EMB treatment efficacy for this purpose is an important issue for salmon producers around the world, and particularly for those in the Atlantic Ocean where widespread EMB tolerance in sea lice is recognized as a significant problem. Salmon farms in the Northeast Pacific Ocean have not historically experienced the same issues with treatment efficacy, possibly due to the relatively large population of endemic salmonid hosts that serve to both redistribute surviving lice and dilute populations potentially under selection by introducing naïve lice to farms. Frequent migration of lice among farmed and wild hosts should limit the effect of farm-specific selection pressures on changes to the overall allele frequencies of sea lice in the Pacific Ocean. A previous study using microsatellites examined L. salmonis oncorhynchi from 10 Pacific locations from wild and farmed hosts and found no population structure. Recently however, a farm population of sea lice was detected where EMB bioassay exposure tolerance was abnormally elevated. In response, we have developed a Pacific louse draft genome that complements the previously-released Atlantic louse sequence. These genomes were combined with whole-genome re-sequencing data to design a highly sensitive 201,279 marker SNP array applicable for both subspecies (90,827 validated Pacific loci; 153,569 validated Atlantic loci). Notably, kmer spectrum analysis of the re-sequenced samples indicated that Pacific lice exhibit a large within-individual heterozygosity rate (average of 1 in every 72 bases) that is markedly higher than that of Atlantic individuals (1 in every 173 bases). The SNP chip was used to produce a high-density map for Atlantic sea louse linkage group 5 that was previously shown to be associated with EMB tolerance in Atlantic lice. Additionally, 478 Pacific louse samples from farmed and wild hosts obtained between 2005 and 2014 were also genotyped on the array. Clustering analysis allowed us to detect the apparent emergence of an otherwise rare genotype at a high frequency among the lice collected from two farms in 2013 that had reported elevated EMB tolerance. This genotype was not observed in louse samples collected from the same farm in 2010, nor in any lice sampled from other locations prior to 2013. However, this genotype was detected at low frequencies in louse samples from farms in two locations reporting elevated EMB tolerance in 2014. These results suggest that a rare genotype present in Pacific lice may be locally expanded in farms after EMB treatment. Supporting this hypothesis, 437 SNPs associated with this genotype were found to be in a region of linkage group 5 that overlaps the region associated with EMB resistance in Atlantic lice. Finally, five of the top diagnostic SNPs within this region were used to screen lice that had been subjected to an EMB survival assay, revealing a significant association between these SNPs and EMB treatment outcome. To our knowledge this work is the first report to identify a genetic link to altered EMB efficacy in L. salmonis in the Pacific Ocean.
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Affiliation(s)
- Amber M Messmer
- Department of Biology, University of Victoria, Victoria V8W 2Y2, BC, Canada.
| | - Jong S Leong
- Department of Biology, University of Victoria, Victoria V8W 2Y2, BC, Canada.
| | - Eric B Rondeau
- Department of Biology, University of Victoria, Victoria V8W 2Y2, BC, Canada.
| | - Anita Mueller
- Department of Biology, University of Victoria, Victoria V8W 2Y2, BC, Canada.
| | - Cody A Despins
- Department of Biology, University of Victoria, Victoria V8W 2Y2, BC, Canada.
| | - David R Minkley
- Department of Biology, University of Victoria, Victoria V8W 2Y2, BC, Canada.
| | - Matthew P Kent
- Centre for Integrative Genetics (CIGENE), Department of Animal and Aquacultural Sciences, Norwegian University of Life Sciences, Ås, Norway.
| | - Sigbjørn Lien
- Centre for Integrative Genetics (CIGENE), Department of Animal and Aquacultural Sciences, Norwegian University of Life Sciences, Ås, Norway.
| | - Brad Boyce
- Marine Harvest Canada, Campbell River, BC, Canada.
| | | | - Mark D Fast
- Department of Pathology and Microbiology, University of Prince Edward Island, Charlottetown, PEI C1A 4P3, Canada.
| | - Joseph D Norman
- Department of Integrative Biology, University of Guelph, Guelph, ON N1G 2W1, Canada; Present address: The Hospital for Sick Children, 686 Bay St., Toronto, ON M5G 0A4, Canada.
| | - Roy G Danzmann
- Department of Integrative Biology, University of Guelph, Guelph, ON N1G 2W1, Canada.
| | - Ben F Koop
- Department of Biology, University of Victoria, Victoria V8W 2Y2, BC, Canada; Centre for Biomedical Research, University of Victoria, Victoria, BC V8W 3N5, Canada.
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6
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McEwan GF, Groner ML, Burnett DL, Fast MD, Revie CW. Managing aquatic parasites for reduced drug resistance: lessons from the land. J R Soc Interface 2017; 13:rsif.2016.0830. [PMID: 28003529 DOI: 10.1098/rsif.2016.0830] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2016] [Accepted: 11/28/2016] [Indexed: 11/12/2022] Open
Abstract
Atlantic salmon farming is one of the largest aquaculture industries in the world. A major problem in salmon farms is the sea louse ectoparasite Lepeophtheirus salmonis, which can cause stress, secondary infection and sometimes mortality in the salmon host. Sea lice have substantial impacts on farm economics and potentially nearby wild salmonid populations. The most common method of controlling sea louse infestations is application of chemicals. However, most farming regions worldwide have observed resistance to the small set of treatment chemicals that are available. Despite this, there has been little investigation of treatment strategies for managing resistance in aquaculture. In this article, we compare four archetypical treatment strategies inspired by agriculture, where the topic has a rich history of study, and add a fifth strategy common in aquaculture. We use an agent-based model (ABM) to simulate these strategies and their varying applications of chemicals over time and space. We analyse the ABM output to compare how the strategies perform in controlling louse abundance, number of treatments required and levels of resistance in the sea louse population. Our results indicated that among the approaches considered applying chemicals in combination was the most effective over the long term.
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Affiliation(s)
- Gregor F McEwan
- Centre for Veterinary and Epidemiological Research, Department of Health Management, Atlantic Veterinary College, University of Prince Edward Island, 550 University Avenue, Charlottetown, Prince Edward Island, Canada C1A 4P3
| | - Maya L Groner
- Departments of Fisheries Management and Aquatic Health Sciences, Virginia Institute of Marine Science, 1375 Greate Road, Gloucester Point, VA 23062-1346, USA
| | - Danielle L Burnett
- Centre for Veterinary and Epidemiological Research, Department of Health Management, Atlantic Veterinary College, University of Prince Edward Island, 550 University Avenue, Charlottetown, Prince Edward Island, Canada C1A 4P3
| | - Mark D Fast
- Hoplite Research Group, Department of Pathology and Microbiology, Atlantic Veterinary College, University of Prince Edward Island, 550 University Avenue, Charlottetown, Prince Edward Island, Canada C1A 4P3
| | - Crawford W Revie
- Centre for Veterinary and Epidemiological Research, Department of Health Management, Atlantic Veterinary College, University of Prince Edward Island, 550 University Avenue, Charlottetown, Prince Edward Island, Canada C1A 4P3
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7
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Godwin SC, Dill LM, Krkošek M, Price MHH, Reynolds JD. Reduced growth in wild juvenile sockeye salmon Oncorhynchus nerka infected with sea lice. JOURNAL OF FISH BIOLOGY 2017; 91:41-57. [PMID: 28556094 DOI: 10.1111/jfb.13325] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/16/2016] [Accepted: 03/29/2017] [Indexed: 06/07/2023]
Abstract
Daily growth rings were examined in the otoliths of wild juvenile sockeye salmon Oncorhynchus nerka to determine whether infection by ectoparasitic sea lice Caligus clemensi and Lepeophtheirus salmonis was associated with reduced host body growth, an important determinant of survival. Over 98% of the sea lice proved to be C. clemensi and the fish that were highly infected grew more slowly than uninfected individuals. Larger fish also grew faster than smaller fish. Finally, there was evidence of an interaction between body size and infection status, indicating the potential for parasite-mediated growth divergence.
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Affiliation(s)
- S C Godwin
- Earth to Ocean Research Group, Department of Biological Sciences, Simon Fraser University, Burnaby, BC, V5A 1S6, Canada
| | - L M Dill
- Earth to Ocean Research Group, Department of Biological Sciences, Simon Fraser University, Burnaby, BC, V5A 1S6, Canada
| | - M Krkošek
- Department of Ecology and Evolutionary Biology, University of Toronto, Toronto, ON, M5S 3B2, Canada
- Salmon Coast Field Station, Simoom Sound, BC, V0P 1S0, Canada
| | - M H H Price
- Earth to Ocean Research Group, Department of Biological Sciences, Simon Fraser University, Burnaby, BC, V5A 1S6, Canada
- SkeenaWild Conservation Trust, Terrace, BC, V8G 1P2, Canada
| | - J D Reynolds
- Earth to Ocean Research Group, Department of Biological Sciences, Simon Fraser University, Burnaby, BC, V5A 1S6, Canada
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8
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Gautam R, Boerlage AS, Vanderstichel R, Revie CW, Hammell KL. Variation in pre-treatment count lead time and its effect on baseline estimates of cage-level sea lice abundance. JOURNAL OF FISH DISEASES 2016; 39:1297-1303. [PMID: 26916434 DOI: 10.1111/jfd.12460] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/28/2015] [Revised: 12/20/2015] [Accepted: 12/21/2015] [Indexed: 06/05/2023]
Abstract
Treatment efficacy studies typically use pre-treatment sea lice abundance as the baseline. However, the pre-treatment counting window often varies from the day of treatment to several days before treatment. We assessed the effect of lead time on baseline estimates, using historical data (2010-14) from a sea lice data management programme (Fish-iTrends). Data were aggregated at the cage level for three life stages: (i) chalimus, (ii) pre-adult and adult male and (iii) adult female. Sea lice counts were log-transformed, and mean counts by lead time relative to treatment day were computed and compared separately for each life stage, using linear mixed models. There were 1,658 observations (treatment events) from 56 sites in 5 Bay Management Areas. Our study showed that lead time had a significant effect on the estimated sea lice abundance, which was moderated by season. During the late summer and autumn periods, counting on the day of treatment gave significantly higher values than other days and would be a more appropriate baseline estimate, while during spring and early summer abundance estimates were comparable among counts within 5 days of treatment. A season-based lead time window may be most appropriate when estimating baseline sea lice levels.
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Affiliation(s)
- R Gautam
- Department of Health Management and Centre for Vet Epi Research, Atlantic Veterinary College, University of Prince Edward Island, Charlottetown, PE, Canada.
| | - A S Boerlage
- Department of Health Management and Centre for Vet Epi Research, Atlantic Veterinary College, University of Prince Edward Island, Charlottetown, PE, Canada
| | - R Vanderstichel
- Department of Health Management and Centre for Vet Epi Research, Atlantic Veterinary College, University of Prince Edward Island, Charlottetown, PE, Canada
| | - C W Revie
- Department of Health Management and Centre for Vet Epi Research, Atlantic Veterinary College, University of Prince Edward Island, Charlottetown, PE, Canada
| | - K L Hammell
- Department of Health Management and Centre for Vet Epi Research, Atlantic Veterinary College, University of Prince Edward Island, Charlottetown, PE, Canada
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9
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Rittenhouse MA, Revie CW, Hurford A. A model for sea lice (Lepeophtheirus salmonis) dynamics in a seasonally changing environment. Epidemics 2016; 16:8-16. [DOI: 10.1016/j.epidem.2016.03.003] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2015] [Revised: 03/22/2016] [Accepted: 03/25/2016] [Indexed: 11/28/2022] Open
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10
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Elmoslemany A, Revie CW, Milligan B, Stewardson L, Vanderstichel R. Wild juvenile salmonids in Muchalat Inlet, British Columbia, Canada: factors associated with sea lice prevalence. DISEASES OF AQUATIC ORGANISMS 2015; 117:107-120. [PMID: 26648103 DOI: 10.3354/dao02939] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
The Muchalat Inlet, British Columbia, is among the most westerly points at which aquaculture is practiced in Canada. In this paper, we summarise data from over 18000 wild fish sampled at 16 sites over an 8 yr period, between 2004 and 2011. The most prevalent wild species was chum salmon Oncorhynchus keta (82.4%), followed by Chinook O. tshawytscha (10%) and coho O. kisutch (4.3%). However, inter-annual and seasonal variation was evident, and smaller numbers of other Pacific salmon and stickleback species were sporadically observed. A high percentage of wild salmon (~95%) had no sea lice parasites present, with less than 1% of the fish hosting a mobile-stage sea louse. Of the data for which sea lice species were recorded, just over 96% of samples were identified as Lepeophtheirus salmonis. Logistic regression models assessed the association between the presence of lice and a range of independent variables. These models indicated a significant degree of spatial variation, much of which could be explained in terms of salinity levels. There were also important variations through time, both over the season within a year and across years. In addition, coho salmon were significantly more likely (odds ratio = 1.65; 95% CI = 1.20-2.3) to be infected than chum salmon. The protective effect of low salinity was most clearly seen at values lower than 15 psu, although this was dependent on fish species.
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Affiliation(s)
- Ahmed Elmoslemany
- Atlantic Veterinary College, University of Prince Edward Island, 550 University Ave, Charlottetown, Prince Edward Island C1A 4P3, Canada
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11
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McEwan GF, Groner ML, Fast MD, Gettinby G, Revie CW. Using Agent-Based Modelling to Predict the Role of Wild Refugia in the Evolution of Resistance of Sea Lice to Chemotherapeutants. PLoS One 2015; 10:e0139128. [PMID: 26485023 PMCID: PMC4618729 DOI: 10.1371/journal.pone.0139128] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2015] [Accepted: 09/08/2015] [Indexed: 11/18/2022] Open
Abstract
A major challenge for Atlantic salmon farming in the northern hemisphere is infestation by the sea louse parasite Lepeophtheirus salmonis. The most frequent method of controlling these sea louse infestations is through the use of chemical treatments. However, most major salmon farming areas have observed resistance to common chemotherapeutants. In terrestrial environments, many strategies employed to manage the evolution of resistance involve the use of refugia, where a portion of the population is left untreated to maintain susceptibility. While refugia have not been deliberately used in Atlantic salmon farming, wild salmon populations that migrate close to salmon farms may act as natural refugia. In this paper we describe an agent-based model that explores the influence of different sizes of wild salmon populations on resistance evolution in sea lice on a salmon farm. Using the model, we demonstrate that wild salmon populations can act as refugia that limit the evolution of resistance in the sea louse populations. Additionally, we demonstrate that an increase in the size of the population of wild salmon results in an increased effect in slowing the evolution of resistance. We explore the effect of a population fitness cost associated with resistance, finding that in some cases it substantially reduces the speed of evolution to chemical treatments.
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Affiliation(s)
- Gregor F. McEwan
- Centre for Veterinary and Epidemiological Research, Department of Health Management, Atlantic Veterinary College, University of Prince Edward Island, 550 University Ave, Charlottetown, PE, Canada, C1A 4P3
- * E-mail:
| | - Maya L. Groner
- Centre for Veterinary and Epidemiological Research, Department of Health Management, Atlantic Veterinary College, University of Prince Edward Island, 550 University Ave, Charlottetown, PE, Canada, C1A 4P3
| | - Mark D. Fast
- Department of Anatomy and Physiology, Atlantic Veterinary College, University of Prince Edward Island, 550 University Ave, Charlottetown, PE, Canada, C1A 4P3
| | - George Gettinby
- Department of Mathematics & Statistics, University of Strathclyde, Richmond Street, Glasgow, G1 1XH, Scotland, UK
| | - Crawford W. Revie
- Centre for Veterinary and Epidemiological Research, Department of Health Management, Atlantic Veterinary College, University of Prince Edward Island, 550 University Ave, Charlottetown, PE, Canada, C1A 4P3
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Krkošek M, Ashander J, Frazer LN, Lewis MA. Allee effect from parasite spill-back. Am Nat 2013; 182:640-52. [PMID: 24107371 DOI: 10.1086/673238] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
The exchange of native pathogens between wild and domesticated animals can lead to novel disease threats to wildlife. However, the dynamics of wild host-parasite systems exposed to a reservoir of domesticated hosts are not well understood. A simple mathematical model reveals that the spill-back of native parasites from domestic to wild hosts may cause a demographic Allee effect in the wild host population. A second model is tailored to the particulars of pink salmon (Oncorhynchus gorbuscha) and salmon lice (Lepeophtheirus salmonis), for which parasite spill-back is a conservation and fishery concern. In both models, parasite spill-back weakens the coupling of parasite and wild host abundance-particularly at low host abundance-causing parasites per host to increase as a wild host population declines. These findings show that parasites shared across host populations have effects analogous to those of generalist predators and can similarly cause an unstable equilibrium in a focal host population that separates persistence and extirpation. Allee effects in wildlife arising from parasite spill-back are likely to be most pronounced in systems where the magnitude of transmission from domestic to wild host populations is high because of high parasite abundance in domestic hosts, prolonged sympatry of domestic and wild hosts, a high transmission coefficient for parasites, long-lived parasite larvae, and proximity of domesticated populations to wildlife migration corridors.
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Affiliation(s)
- Martin Krkošek
- Department of Ecology and Evolutionary Biology, University of Toronto, Toronto, Ontario M5S 3B2, Canada; and Department of Zoology, University of Otago, Dunedin, New Zealand
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Saksida SM, Morrison D, McKenzie P, Milligan B, Downey E, Boyce B, Eaves A. Use of Atlantic salmon, Salmo salar L., farm treatment data and bioassays to assess for resistance of sea lice, Lepeophtheirus salmonis, to emamectin benzoate (SLICE(®) ) in British Columbia, Canada. JOURNAL OF FISH DISEASES 2013; 36:515-520. [PMID: 23106395 DOI: 10.1111/jfd.12018] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/22/2012] [Revised: 08/31/2012] [Accepted: 09/11/2012] [Indexed: 06/01/2023]
Affiliation(s)
- S M Saksida
- BC Centre for Aquatic Health Sciences, Campbell River, BC, Canada.
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Rogers LA, Peacock SJ, McKenzie P, DeDominicis S, Jones SRM, Chandler P, Foreman MGG, Revie CW, Krkošek M. Modeling parasite dynamics on farmed salmon for precautionary conservation management of wild salmon. PLoS One 2013; 8:e60096. [PMID: 23577082 PMCID: PMC3618109 DOI: 10.1371/journal.pone.0060096] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2012] [Accepted: 02/22/2013] [Indexed: 11/24/2022] Open
Abstract
Conservation management of wild fish may include fish health management in sympatric populations of domesticated fish in aquaculture. We developed a mathematical model for the population dynamics of parasitic sea lice (Lepeophtheirus salmonis) on domesticated populations of Atlantic salmon (Salmo salar) in the Broughton Archipelago region of British Columbia. The model was fit to a seven-year dataset of monthly sea louse counts on farms in the area to estimate population growth rates in relation to abiotic factors (temperature and salinity), local host density (measured as cohort surface area), and the use of a parasiticide, emamectin benzoate, on farms. We then used the model to evaluate management scenarios in relation to policy guidelines that seek to keep motile louse abundance below an average three per farmed salmon during the March–June juvenile wild Pacific salmon (Oncorhynchus spp.) migration. Abiotic factors mediated the duration of effectiveness of parasiticide treatments, and results suggest treatment of farmed salmon conducted in January or early February minimized average louse abundance per farmed salmon during the juvenile wild salmon migration. Adapting the management of parasites on farmed salmon according to migrations of wild salmon may therefore provide a precautionary approach to conserving wild salmon populations in salmon farming regions.
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Affiliation(s)
- Luke A Rogers
- Department of Zoology, University of Otago, Dunedin, Otago, New Zealand.
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Jones PG, Hammell KL, Gettinby G, Revie CW. Detection of emamectin benzoate tolerance emergence in different life stages of sea lice, Lepeophtheirus salmonis, on farmed Atlantic salmon, Salmo salar L. JOURNAL OF FISH DISEASES 2013; 36:209-220. [PMID: 23347188 DOI: 10.1111/jfd.12022] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/29/2012] [Revised: 09/11/2012] [Accepted: 09/19/2012] [Indexed: 06/01/2023]
Abstract
Emamectin benzoate has been used to treat sea lice, Lepeophtheirus salmonis, infestations on farmed Atlantic salmon, Salmo salar. Recent evidence suggests a reduction in effectiveness in some locations. A major challenge in the detection of tolerance emergence can be the typically low proportion of resistant individuals in a population during the early phases. The objectives of this study were to develop a method for determining differences in temporal development of tolerance between sea lice life stages and to explore how these differences might be used to improve the monitoring of treatment effectiveness in a clinical setting. This study examined two data sets based on records of sea lice abundance following emamectin benzoate treatments from the west coast of Scotland (2002-2006) and from New Brunswick, Canada (2004-2008). Life stages were categorized into two groups (adult females and the remaining mobile stages) to examine the trends in mean abundance and treatment effectiveness. Differences in emamectin benzoate effectiveness were found between the two groups by year and location, suggesting that an important part of monitoring drug resistance development in aquatic ectoparasites may be the need to focus on key life stages.
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Affiliation(s)
- P G Jones
- Centre for Veterinary Epidemiological Research, Department of Health Management, Atlantic Veterinary College, University of Prince Edward Island, Charlottetown, Prince Edward Island, Canada.
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Torrissen O, Jones S, Asche F, Guttormsen A, Skilbrei OT, Nilsen F, Horsberg TE, Jackson D. Salmon lice--impact on wild salmonids and salmon aquaculture. JOURNAL OF FISH DISEASES 2013; 36:171-94. [PMID: 23311858 PMCID: PMC3675643 DOI: 10.1111/jfd.12061] [Citation(s) in RCA: 167] [Impact Index Per Article: 15.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/05/2012] [Revised: 10/15/2012] [Accepted: 10/17/2012] [Indexed: 05/04/2023]
Abstract
Salmon lice, Lepeophtheirus salmonis, are naturally occurring parasites of salmon in sea water. Intensive salmon farming provides better conditions for parasite growth and transmission compared with natural conditions, creating problems for both the salmon farming industry and, under certain conditions, wild salmonids. Salmon lice originating from farms negatively impact wild stocks of salmonids, although the extent of the impact is a matter of debate. Estimates from Ireland and Norway indicate an odds ratio of 1.1:1-1.2:1 for sea lice treated Atlantic salmon smolt to survive sea migration compared to untreated smolts. This is considered to have a moderate population regulatory effect. The development of resistance against drugs most commonly used to treat salmon lice is a serious concern for both wild and farmed fish. Several large initiatives have been taken to encourage the development of new strategies, such as vaccines and novel drugs, for the treatment or removal of salmon lice from farmed fish. The newly sequenced salmon louse genome will be an important tool in this work. The use of cleaner fish has emerged as a robust method for controlling salmon lice, and aquaculture production of wrasse is important towards this aim. Salmon lice have large economic consequences for the salmon industry, both as direct costs for the prevention and treatment, but also indirectly through negative public opinion.
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Affiliation(s)
- O Torrissen
- Institute of Marine Research, Nordnes, Bergen, Norway.
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Larrat S, Marvin J, Lair S. Safety and efficacy of emamectin benzoate to treat Anguillicoloides crassus (Kuwahara, Niimi & Itagaki) infections in American eels, Anguilla rostrata (Lesueur). JOURNAL OF FISH DISEASES 2012; 35:467-470. [PMID: 22486309 DOI: 10.1111/j.1365-2761.2012.01366.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Affiliation(s)
- S Larrat
- Centre québécois sur la santé des animaux sauvages, Faculté de médecine vétérinaire, Université de Montréal, St-Hyacinthe, QC, Canada
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