Canadian Aquaculture R&D Review 2011

Sea Lice

Spatial distribution of planktonic sea lice in the Broughton Archipelago

Weather station maintenance at Surgeon Island

Development of effective farm location and management practices requires ongoing knowledge of where the sea lice larvae are located, how far and fast they spread from farm sources of adult sea lice and eggs, and how long the larvae remain present and infective after outputs from the farm sources are reduced by treatment or harvest. In support of this goal, this project accessed the distribution of planktonic larval sea lice in Knight Inlet and the Broughton Archipelago. Sampling was conducted in mid-late autumn (Nov-Dec; after the return migration of adult wild fish, but before mid-winter fallowing and pesticide treatments), when we anticipated that sea lice larval numbers may be higher in order to give us a more accurate picture of larval sea lice drift. However, larval sea lice abundances remained relatively low in the 2009 samples. This may be due to SLICE® applications and harvesting at farm sites 1-2 months earlier than in the previous year. Past works concentrated on getting into the field before the smolt out–migration. These previous studies showed that although spring season abundances of the sea lice larvae were quite low in 2007 and 2008 (and at detection limit in 2009), local spatial maxima of the sea lice larvae were consistently located near active fish farms. The spatial association was strongest for the nauplius but was also significant and persistent for the copepodite infective stage. The fall distribution of planktonic stages is similar to spring; Lepeophtheirus salmonis more closely associated with farms sites and Caligus clemensi further afield. The project provided validation data for the Stucchi and Foreman computer model of sea lice dispersal and advection. Sampling was undertaken where the model showed 'hot spots' of accumulation by wind and currents on the outer reaches of the Broughton Archipelago. In this region, the numbers of sea lice larvae were not large but were located in areas as defined by the model.

Jan. 2009 – Dec. 2009 • Funded by: DFO – Program for Aquaculture Regulatory Research, DFO Science
Project team: Moira Galbraith (DFO), Dave Mackas (DFO)
Contact:Moira Galbraith ( Moira.Galbraith@dfo-mpo.gc.ca), Dave Mackas ( Dave.Mackas@dfo-mpo.gc.ca)

Bioassay protocol development to determine susceptibility of sea lice from BC salmon farms to therapeutants

This BC Centre for Aquatic Health Sciences (BC CAHS) project concerned with the transfer of bioassay procedures from the AVC Centre for Aquatic Health Sciences in PEI and international research facilities to BC CAHS. These methods were further adapted to the field and laboratory conditions and to the sea lice species found in British Columbia. Initial development of the bioassay protocol was supported by Intervet Schering-Plough and Marine Harvest Canada. Since April 2010, nine bioassays have been conducted. All assays tested for susceptibility to SLICE® (emamectin benzoate), which is the only sea lice therapeutant currently available in BC. All bioassays showed good susceptibility of sea lice to SLICE® – this finding corroborates efficacy studies of BC sea lice treatments with this therapeutant.

Mar. 2010 – Oct. 2010 • Funded by: Intervet Schering-Plough, Marine Harvest Canada
Project team: Alexandra Eaves, Sonja Saksida (BC CAHS), Intervet Schering-Plough, Marine Harvest Canada, Marine Harvest, Atlantic Veterinary College's Centre for Aquatic Health Sciences
Contact: Sonja Saksida ( sonja.saksida@cahs-bc.ca) http://www.cahs-bc.ca

Formalin preserved newly hatched sea lice (Lepeophtheirus salmonis) at nauplii stages I and II, as viewed though a microscope. Background reference grid is 1 mm

Modeling sea lice dispersion and encounter rates with juvenile Pacific Salmon

Sea lice dispersion modeling initiated by the Pacific Salmon Forum and the Program for Aquaculture Regulatory Research (DFO) is continuing in collaboration with the new Broughton Archipelago Management Plan (BAMP) project whose objective is to explore means for reducing the potential for sea lice from farmed salmon to infect juvenile Pink and Chum Salmon during the outward migration season. Sea lice copepodid concentrations will be computed by coupled circulation and dispersion models for the Broughton Archipelago and used to estimate encounter rates with juveniles migrating seaward along pre-specified routes. The model grids have been improved to provide increased resolution around farms and coastlines, and various coastal boundary approximations will be tested to determine their effects on sea lice retention. A hindcast simulation for May 2008 will be compared with a similar run for March 2008 in order to estimate the impact of freshwater on sea lice mortality. A May 2010 run will also be compared with May 2008 to assess inter-annual variability. Methodologies to compare these concentrations and encounter rates with values arising from BAMP's wild salmon monitoring program will also be investigated. In the second year of the project, model coverage will be extended to the Discovery Islands area utilizing the circulation component of a viral transmission model that is presently under development with funding from Aquaculture Collaborative Research and Development Program.

June 2010 – Mar. 2011 • Funded by: DFO – Program for Aquaculture Regulatory Research, Marine Harvest Canada Project team:Mike Foreman (DFO), Dario Stucchi (DFO), Darren Tuele (DFO), Moira Galbraith (DFO), Peter Chandler (DFO), Crawford Revie (UPEI), Sharon DeDimonicis, Craig Orr, Ming Guo Contact: Mike Foreman ( Mike.Foreman@dfo-mpo.gc.ca) • /aquaculture/parr-prra/types-eng.asp

Environmental fate of SLICE® (emamectin benzoate) in saltwater aquaculture

Sea lice infestation at marine cage finfish farms in Canada are most often treated by the application of the anti-parasitic chemotherapeutant SLICE®. Concerns regarding the potential effect and uptake of the active compound in this treatment, emamectin benzoate (EB), by nontarget organisms have been raised by numerous stakeholder groups. The goals of this project are to measure EB environmental levels, conduct laboratory exposure experiments at environmentally relevant concentrations where water, sediment and tissue concentrations can be measured, and to use genomic techniques to assess toxicological impacts on Spot Prawns.

As part of the field study, the benthic fate and concentration of EB and its desmethyl metabolite were evaluated following the application of SLICE® at finfish farm sites in BC. Ultra-trace analytical methodologies based on liquid chromatography electrospray ionization mass spectrometry were developed at DFOIOS to measure EB in sediments, water and tissue matrices at low to sub parts per billion (ppb) levels. Preliminary data of the EB concentrations measured in the sediments near a salmon farm treated with SLICE® are presented in the figure below. The EB levels measured at the reference site were close to the limit of quantitation and were consistently low throughout the entire sampling period. At this site, the EB concentrations were highest underneath the net-pen (i.e., W0 and E0) with the highest concentration reaching 30 ppb some three weeks after SLICE® treatment commenced. These findings suggest that EB emerging from this salmon farm after SLICE® treatment were sequestered in the sediments in close proximity to the fish farm, i.e., within a 60 to 100 meter radius from the farm site. Residues of EB seem to dissipate over time and with distance from the net-pens. These EB profiles are specific to this site and may not be extrapolated to other sites. It is evident from our on-going work that the EB profiles in the sediments are site dependent and are closely related to the deposition characteristics of the specific location. Sites with low deposition characteristics had very low levels of EB (sub-ppb) in the sediments underneath the net-pen following SLICE® treatment.

Sediment, water, and Spot Prawn samples were collected from several sites treated with SLICE® and have been analyzed for EB. Presently we are analyzing these data for relationships between environmental concentrations and toxicological findings. The measured environmental EB concentrations are also being used to test, calibrate and implement the DEPOMOD model to predict the behaviour of EB in relevant aquatic ecosystems. These findings will be useful in developing policy for SLICE® utilization.

Nov. 2008 – Mar. 2012 • Funded by: DFO – Program for Aquaculture Regulatory Research, BC Ministry of the Envioronment, Pacific Salmon Forum, Pacific Prawn Fishers Association (PPFA))
Project team:Michael Ikonomou (DFOIOS), John Chamberlain (BC Ministry of Agriculture and Lands), Eric McGreer (BC Ministry of Environment), Cory Dubetz (DFOIOS), Chris Sporer (Pacific Prawn Fishers Association (PPFA)
Contact:Michael Ikonomou ( Michael.Ikonomou@dfo-mpo.gc.ca)

EB concentrations (ppb wet weight) as measured in surface sediment samples collected at a salmon farm site along East (E) and West (W) transects over four months of sampling. Samples were collected at specific distances East and West from the farm at 0 meters (m), 30 m, 60 m, 100 m and 150 m as well a reference (Ref) site. Average moisture level for all samples was determined to be 69.7% ± 11.4%

Can sea lice carry and transmit bacterial and viral pathogens to salmon?

The role of ectoparasitic sea lice in disease propagation (as a possible vector) or in progression (impacts on the host's immunology) has not been explored. There are two phases of research underway in our lab: 1) experimental testing of the potential of sea lice as a pathogen vector – through acquisition and transfer of Aeromonas salmonicida and infectious haematopoietic necrosis virus (IHNv) between salmon hosts; and 2) the genetic examination of changes in the salmon immune response to sea lice feeding to test the hypothesis that sea lice feeding activities promote small, localised patches of reduced immune response, potentially acting as portals of pathogen entry. For objective 1, we have evidence that sea lice can acquire A. salmonicida and IHNv passively from waterborne exposure; however, the concentrations must be very high (similar to a disease outbreak). We also have evidence that sea lice can acquire these pathogens from feeding on infected salmon (Atlantic, Pink, or Chum). Our current experiments are examining the hypothesis that infected sea lice can transmit these pathogens to uninfected salmon, thereby completing the cycle of host → vector → host. For objective 2, data suggest that there are distinct differences among Atlantic, Pink, and Chum Salmon in genomic expression of various immune-associated genes. Pink Salmon have been found to have significantly elevated levels of interleukin-1, Beta (IL1β) (inflammatory responses). In addition, there are differences in the amount of gene expression from 24-48 hours post exposure to sea lice, with Atlantic Salmon often showing the highest initial expression. These studies continue with the addition of new variables including responses at the cellular level, the presence of bacteria, and duration of expression. As we progress through our second year of this project, the role of sea lice as a vector remains unclear. Thus, much of our current focus is on replication of transmission challenges through the examination of several key variables:

  • vector potential between male and female sea lice;
  • host susceptibility to 'contaminated' sea lice (i.e., sea lice from infected Atlantic Salmon transferred to uninfected Pacific salmon and vice-versa);
  • behaviour/viability of sea lice in varying environmental conditions (i.e., temperature, salinity) when carrying bacteria; and
  • immunohistochemical detection methods of the pathogens on/in the sea lice.

2009 – 2012 • Funded by: NSERC Strategic Grant
Project team: Duane Barker (Vancouver Island University), Simon Jones (DFO), Kyle Garver (DFO), Diane Morrison (Marine Harvest), Brad Boyce (Marine Harvest), Stewart Johnson (DFOPBS), Sonja Saksida (BC Centre for Aquatic Health Sciences), Luis Alfonso (BC Centre for Aquatic Health Sciences), Ben Koop (University of Victoria), Scott McKinley (University of BC), Eva Jakob (UVI), Laura Braden (UVI), Colin Novak (UVI), Danielle Lewis (UVI)
Contact: Duane Barker ( duane.barker@viu.ca)

Bacterial culture plate

Development of genomics tools to assess potential biological effects of SLICE® on Spot Prawns

SLICE® (emamectin benzoate (EB)) is used in medicated feed to control against juvenile motile pre-adult and adult stages of sea lice species on farmed salmon. EB enters the aquatic environment in uneaten feed and via fish feces. Concerns regarding the potential effects and uptake of EB by non-target organisms have been raised by numerous stakeholder groups. Genomic methodologies were developed to assess the risk of sub-lethal effects of EB on Pacific Spot Prawn, Pandalus platyceros, under laboratory conditions. Spot Prawns were exposed to selected concentrations (100, 400, 800, 1200 and 4800 ppb) of EB for up to 8 days. EB was spiked into the sediments placed in the aquariums where the spot prawn where placed.

It is well-established that RNA production varies with many environmental conditions and that differential gene expression does not necessarily indicate changes in protein production or cellular functions. The results from this study indicated changes in differential gene expression within muscle tissue from Spot Praws exposed to the selected EB concentrations under these laboratory conditions. Accordingly, work is now proceeding to determine if the alterations are functionally relevant or meaningful. Additional cloning and QPCR initiatives have been undertaken that include a cDNA subtraction technique. This PCR-driven methodology will focus the design of QPCR tools for further screening of EB–exposed Spot Prawn. In addition to the laboratory exposed animals, we will also examine animals collected in the field close to fish farms following SLICE® treatment.

Apr. 2009 – Mar. 2011 • Funded by: DFO – Program for Aquaculture Regulatory Research (PARR), BC-MOE, Environment Canada (EC), PSF, University of Victoria
Project team:Michael Ikonomou (DFO), Caren Helbing (University of Victoria), Nik Veldhoen (University of Victoria), Cory Dubetz (DFO), Jon Chamberlain (Ministry of Agriculture and Lands), Graham van Aggelen (EC), Craig Buday (EC)
Contact: Michael.Ikonomou@dfo-mpo.gc.ca

Genomics in Lice and Salmon (GiLS): using genomics to combat sea lice infections in salmon

Sea lice infections of salmon populations can threaten this important economic and environmental resource in British Columbia. Costs to the Canadian salmon industry to treat sea lice infections, keep farm stock healthy, and minimize environmental impact have been estimated at 10 to 20 percent of the total landed value, or more than $50 million in 2010.

The Genome BC-funded team of researchers (University of Victoria's Ben Koop, Simon Fraser University's William Davidson, Fisheries & Oceans Canada's Simon Jones, and Vancouver Island University's Grant Murray) is using microarray technology to examine gene expression patterns of both salmon and sea louse to identify which genes undergo significant changes in expression during infection. Identification of genetic markers in sea lice will enable the examination of population characteristics, including migration patterns, origins and selection, which will in turn provide information about the genetic factors that influence the host–pathogen response.

The team is identifying common genetic elements required for infection that could provide potential targets against which therapeutics can be developed to affect both species of sea louse. The analysis will provide important insight into the host-pathogen interaction, including the identification of resistant strains of salmon and more virulent strains of sea louse. This genomic strategy can also be employed to investigate the environmental variables that influence infection in order to potentially limit infection in farmed salmon populations.

Barker Lab team

Oct. 2008 - ongoing • Funded by: Genome British Columbia, BC Ministry of Agriculture and Lands, Fisheries and Oceans Canada (DFO), Grieg Seafood BC Ltd., Mainstream Canada, Marine Harvest Microtek Research and Development Ltd., University of Victoria, Vancouver Island University
Project team: Ben Koop (U of Victoria), Grant Murray (VIU), Simon Jones (DFOPBS), William Davidson (SFU)
Contact: Ben Koop ( bkoop@uvic.ca) • http://web.uvic.ca/grasp/gils/

The biology of juvenile Pink Salmon and the impact of sea lice on the earliest stages of Pink Salmon in seawater

This study investigated the biology of juvenile Pink Salmon (Oncorhynchus gorbuscha) and the impacts of sea lice, (Lepeophtheirus salmonis), on the earliest stages of Pink Salmon in seawater. Controlled laboratory experiments were performed under natural conditions at a fallowed fish farm at Doctors Islet. Additional non-field based laboratory studies were performed at the Centre for Aquaculture and Environmental Research in West Vancouver and at UBC.

The research objectives were to perform sound laboratory and field studies to increase basic knowledge on the ionoregulatory physiology and performance of developing juvenile Pink Salmon and the effects of varying sea lice densities on these functions. The six research studies revealed that:

  1. The relatively early entry of Pink Salmon into seawater (at about 0.3 g body mass) occurs prior to full physiological readiness for seawater life when compared to other anadromous salmonids. At this life stage, they have a strong preference for the top 1-2 meters of the water column.
  2. The voracious appetite and high growth rate in seawater can result in a doubling of body mass each month. After about 1-2 months of such growth, seawater readiness appears complete.
  3. Juvenile Pink Salmon were discovered to be more resilient to controlled infections of sea lice copepodids than previously thought. Very little fish mortality was observed over a 1-month period of infection. Juveniles could lose sea lice (as previously reported in all controlled infection studies) and increased body mass even as the sea lice developed towards adult stages.
  4. The swimming performance and ionic balance of Pink Salmon was disrupted by sea lice infections only when the juveniles were less than 0.5-0.7 g in body mass.
  5. The vertical and diurnal distribution of Pink Salmon was influenced by the presence of sea lice in a 10 m water column

Feb. 2007 – Mar. 2011 • Funded by: British Columbia Pacific Salmon Forum, Natural Sciences and Engineering Research Council of Canada (NSERC)
Project team: A. P. Farrell (UBC), C. J. Brauner (UBC), L. Nendick (UBC), S. Tang (UBC),M. Sackville (UBC), A. M. Grant (UBC), M. Gardner (UBC), L. M. Hanson (UBC), A. G. Lewis (UBC), C. DiBacco (UBC)
Contact: A. P. Farrell ( farrellt@mail.ubc.ca) http://people.landfood.ubc.ca/anthony.farrell/

Pink salmon juveniles

Sea lice infection of juvenile Pink Salmon: effects on swimming performance and post-exercise ion balance

Sea lice (Lepeophtheirus salmonis) infection negatively affected swimming performance and post-swim body ion concentrations of juvenile Pink Salmon (Oncorhynchus gorbuscha) at a 0.34 g average body mass but not at 1.1 g. Maximum swimming velocity (Umax) was measured on over 350 individual Pink Salmon (0.2–3.0 g), two–thirds of which had a sea lice infection varying in intensity (one to three sea lice per fish) and life stage (chalimus 1 to preadult). For fish averaging 0.34 g (caught in a nearby river free of sea lice and transferred to seawater before being experimentally infected), the significant reduction in Umax was dependent on sea lice life stage, not intensity, and Umax decreased only after the chalimus 2 life stage. Experimental infections also significantly elevated post-swim whole body concentrations of sodium (by 23%–28%) and chloride (by 22%–32%), but was independent of sea lice developmental stage or infection intensity. For fish averaging 1.1 g (captured in seawater with existing sea lice), the presence of sea lice had no significant effect on either Umax or post-swim whole body ions. Thus, a single L. salmonis impacted swimming performance and post-swim whole body ions of only the smallest Pink Salmon and with a sea louse stage of chalimus 3 or greater.

Sept. 2009 – Apr. 2012 • Funded by: British Columbia Pacific Salmon Forum, Natural Sciences and Engineering Research Council of Canada (NSERC)
Project team: L. Nendick (UBC), M. Sackville (UBC), S. Tang (UBC), A. P. Farrell (UBC), C. J. Brauner (UBC)
Contact: L. Nendick ( laura.nendick@gmail.com) http://people.landfood.ubc.ca/anthony.farrell/

Pink Salmon osmoregulatory development plays a key role in sea louse tolerance

Sea lice (Lepeophtheirus salmonis) of fish farm origin have been implicated in reducing Pink Salmon (Oncorhynchus gorbuscha) populations in British Columbia's Broughton Archipelago. Due to the physically disruptive nature of sea louse attachment to fish skin in a hyperosmotic environment, we hypothesize that impacts on fish performance are ionoregulatory in origin. Ionoregulatory status was measured in juvenile Pink Salmon artificially infected in the laboratory and naturally infected in the wild. Body [Na+] of laboratory-infected fish (approximately 1 wk SW; 0.2-0.4 g) increased significantly by 12% with a single chalimus 4 sea louse, and by 23% with 2-3 chalimus 3 sea lice. Mortality over this 24- day trial was 2.4% for fish initially infected with 1-3 sea lice. Body [Na+] for fish caught with natural infections (approximately 4-12 wks SW; 0.5-1.5 g) did not differ from uninfected controls. Combining data sets revealed body mass threshold of 0.5 g for fish infected with one chalimus 4 sea louse above which there was no effect on body ions. We propose that this size-related sea louse tolerance is associated with normal development of better hypoosmoregulatory abilities, adding to a previously suggested multi-factorial mechanism based on epidermal and immune system development. We suggest management bodies consider this fish mass threshold when planning to minimize risk to wild fish populations.

Feb. 2007 – Mar. 2011 • Funded by: British Columbia Pacific Salmon Forum, Natural Sciences and Engineering Research Council of Canada (NSERC) Project team:M. Sackville (UBC), S. Tang (UBC), L. Nendick (UBC), A. P. Farrell (UBC), C. J. Brauner (UBC) Contact:M. Sackville ( mikesack@zoology.ubc.ca) http://people.landfood.ubc.ca/anthony.farrell/

Modeling in support of Coordinated Area Management Production plan

As part of a British Columbia Pacific Salmon Forum (PSF) project, Dario Stucchi and Mike Foreman developed two computer models for the Broughton Archipelago: i) a three-dimensional numerical circulation model that, with appropriate forcing for specific time periods, is capable of simulating velocity, salinity and temperature fields throughout the region; and ii) a model of sea lice dispersal and development/behaviour that uses the 3D circulation model currents to disperse the planktonic larvae and model temperature and salinity fields to control their development and mortality. The Broughton aquaculture industry has recently proposed a Coordinated Area Management Production (CAMP) plan wherein a combination of SLICE® treatments and fallowing will be used to minimize potential sea lice infections on wild juvenile salmon migrating seaward past fish farms. As a guide to the future implementation of CAMP and in consultation with industry, we propose using our two models to investigate how the 2008 infective pressures would have changed under different treatment/fallowing scenarios.

Apr. 2009 – Mar. 2010 • Funded by: DFO - Program for Aquaculture Regulatory Research (PARR)
Project team: Dario Stucchi (DFOIOS), Mike Foreman (DFOIOS)
Contact: Dario Stucchi ( Dario.Stucchi@dfo-mpo.gc.ca), Mike Foreman ( Mike.Foreman@dfo-mpo.gc.ca)

Diel vertical distribution of early marine phase juvenile Pink Salmon and behaviour when exposed to sea lice

We observed diel vertical migration patterns in juvenile Pink Salmon (Oncorhynchus gorbuscha) and tested the hypothesis that fish behaviour is altered by exposure to sea lice copepodids. Experiments involved replicated field deployments of a large (9 m) plankton column, which provided a vertical distribution enclosure under natural light and salinity conditions. Diel vertical distributions of juvenile Pink Salmon were observed during the first three weeks of seawater acclimation both in the presence and absence of the ectoparasitic sea louse (Lepeophtheirus salmonis). Immediately upon entering seawater, juvenile Pink Salmon preferred the top 1 m of the water column, but they moved significantly deeper down the vertical water column as seawater acclimation time increased. A significant diel migration pattern was observed, which involved a preference for the surface at night-time, compared with daytime. When fish in the column were exposed to L. salmonis copepodids for 3 h, 43-62% of fish became infected, fish expanded their vertical distribution.

Feb. 2007 – Mar. 2011 • Funded by: British Columbia Pacific Salmon Forum, Natural Sciences and Engineering Research Council of Canada (NSERC)
Project team: S. Tang (UBC), A. G. Lewis (UBC), M. Sackville (UBC), L. Nendick (UBC), C. DiBacco (UBC), A. P. Farrell (UBC), C. J. Brauner (UBC)
Contact: S. Tang ( ubcsteve@gmail.com) http://people.landfood.ubc.ca/anthony.farrell/

Mixing in wellboats and cage treatment tarps and skirts

Chemical therapeutants are used as part of integrated pest management strategies by salmon growers in southwest New Brunswick to combat sea lice infestations. Efficient mixing of chemical therapeutants in treatment tarps and skirts and wellboat wells is desired for treatment efficacy. Studies took place in two well boats, the Ronja Carrier and Ronja, and at several farm sites, utilizing different chemical delivery systems. Fluorescent dye was injected into treatment vesicles with chemical therapeutants, following industry practices. Dye concentrations were measured at multiple locations and at multiple depths during the treatment period with fluorometers and the movement of dye was visually evaluated with time lapse photography. Results showed that mixing within wells was generally achieved approximately 10 minutes after the addition of the chemical and dye. The type of recirculation system in the wells impacts the rate of mixing. In tarps and skirts, the amount of time taken for the dye concentrations at the different locations to converge was far more variable and in general took longer than within the wellboat wells. It should be noted that mixing in wells was studied without the presence of fish, while mixing in tarps and skirts was monitored with fish present. Further work elucidating the importance of chemical dispersal method and behaviour of fish in mixing is planned.

Jun. 2010 – Mar. 2011 • Funded by: DFO – Program for Aquaculture Regulatory Research (PARR), DFO – Aquaculture Innovation and Market Access Program (AIMAP) Project team: Fred Page (DFOSABS), Randy Losier (DFOSABS), Paul McCurdy (DFOSABS), Jack Fife (DFOSABS), Jiselle Bakker (DFOSABS), Blythe Chang (DFOSABS), Mike Beattie (NBDAAF), Bruce Thorpe (NBDAAF), Kathy Brewer-Dalton (NBDAAF)
Contact: Fred Page ( Fred.Page@dfo-mpo.gc.ca)

NBSGA wellboat Ronja Carrier

The ECO-Bath cage system: eco-friendly, safe and cost-effective ectoparasite control in finfish aquaculture operations

Sea lice have a global economic impact on salmonid aquaculture through loss of stock, product downgrades and costs involved in monitoring and managing infections. A sea lice epidemic recently occurred in New Brunswick as local sea lice populations become tolerant to a limited number of treatments. Present in-bath treatment methods are hampered by difficulties in obtaining and maintaining effective dose concentrations. Project partners are evaluating a new treatment system that will allow cost-effective field bathing treatments while minimizing total environmental impact from the sea lice treatment. Phase I was conducted in environmentally-controlled tanks. This experiment determined that there was no difference in pesticide toxicity between pre- and post-treatment fish when oxygen was infused to very high concentrations in the treatment bath water. Phase II is designing a commercial-scale ECO-Bath system to efficiently treat entire cages/sites while reducing total pesticide usage to a fraction of that presently required. Phase III field trials will evaluate the effectiveness of the ECO-Bath system to minimize total fish stress and mortality during commercial-scale treatments. The ECO-Bath system will increase productivity and operational efficiency through improvement of present fish health management tools and provide a green solution to sea lice control by dramatically minimizing pesticide discharge to the environment.

May 2010 – Mar. 2011 • Funded by: Aquaculture Innovation and Market Access Program, New Brunswick Innovation Foundation
Project team: Evan Kearney (Admiral Fish Farms), Amber Garber (Huntsman Marine Science Centre), Chris Bridger (Aquaculture Engineering Group), Phil Dobson (Aquaculture Engineering Group), Bill Hogans (Huntsman Marine Science Centre), Jack Pendleton (Admiral Fish Farms), James Snider (inVentures Technologies), Craig Glassford (inVentures Technologies), Mike Beattie (NB-DAAF), Kathy Brewer-Dalton (NB-DAAF), Clarence Blanchard (Future Nets)
Contact: Evan Kearney ( ekearney@admiralfishfarms.com),Amber Garber ( agarber@huntsmanmarine.ca)

Effects of anti-sea lice pesticides on non-target organisms

"Sea lice" is a general name for ectoparasitic crustacean copepods that infest Atlantic Salmon. Severe infestations in aquaculture situations have led to loss of fish and revenue wherever salmon aquaculture has been practiced. In Canada, treatment with drugs and pesticides is required when infestations reach threshold levels defined by regulators and fish health professionals. Under current treatment practices, the drug or pesticide is released to the surrounding environment after the treatment, raising concerns about the potential risk to non-target organisms. Laboratory tests have shown that these dispersed therapeutants can be toxic to the American Lobster, which is often harvested close to aquaculture cage sites in Eastern Canada. Dr. Burridge's group has been investigating the nature of the pesticide AlphaMax® (active ingredient deltamethrin) lethal thresholds to the lobster and other crustaceans. Preliminary estimates of the 24-h lethality to lobsters range from 0.01 to 0.14 μg L-1, depending on life-stage. Mysid shrimp are very sensitive to this product but sand shrimp are less sensitive than other species tested. These data, considered along with the results of dye dispersion studies conducted by Dr. Fred Page, will help assess the risk associated with the use of this product.

Apr. 2010 – Mar. 2011 • Funded by: DFO - Program for Aquaculture Regulatory Research (PARR)
Project team: Les Burridge (DFOSABS), Monica Lyons (DFOSABS), David Wong (DFOSABS), Ken MacKeigan (DFOSABS),Susan Waddy (DFOSABS), Vicky Merritt-Carr (DFOSABS)
Contact: Les Burridge ( Les.Burridge@dfo-mpo.gc.ca)

Lobster Larvae

Potential for capture of chemical therapeutant active ingredients prior to release into environment

Chemical therapeutants are part of the integrated pest management strategies used by salmon growers for the control and management of sea lice. Current treatment technologies, wellboats and bath treatments, release the therapeutants into the surrounding environment once treatment is complete. While characterizing exposure and consequence of therapeutants is a time consuming and costly research effort, capturing the active ingredients prior to release would eliminate many of the questions concerning the use of chemical therapeutants in the aquatic environment and our reliance on effective risk management. For instance, preliminary trials using activated charcoal to filter Salmosan® (azamethiphos) and Alphamax® (deltamethrin) have shown > 90% efficacy in removing active ingredients. Planning for possible integration of charcoal filtration with emerging new cage treatment technology has begun. Exploration of methods for deactivating the therapeutants is also underway, given that filtration is challenging in wellboats due to the rates of water exchange.

Dec. 2010 – Mar. 2011 • Funded by: Department of Agriculture, Aquaculture and Fisheries of New Brunswick, Cooke Aquaculture Inc., Admiral Fish Farms, Northern Harvest Sea Farms, New Brunswick Total Development Fund
Project team:Mike Beattie (NBDAAF), Bruce Thorpe (NBDAAF), Kathy Brewer-Dalton (NBDAAF), Jiselle Bakker (DFOSABS), Research and Productivity Council (RPC),Huntsman Marine Science Centre
Contact:Mike Beattie ( Mike.beattie@gnb.ca)

Double and triple SLICE® dosage residue times in Atlantic Salmon

SLICE® (active ingredient emamectin benzoate) is an in-feed sea lice treatment for salmon in southwest New Brunswick and the only registered product to treat sea lice in Canada. Due to some instances of suspected tolerance and a continuing need for sea lice management, increased dosages are becoming more widely used. The purpose of this project is to establish the depletion curve for double and triple doses of emamectin benzoate (100 μg kg-1 and 150 μg kg-1 emamectin benzoate for 7 days, respectively) in salmon under controlled conditions and to validate the above using field–collected samples from a range of size classes and a variety of environmental conditions. This information is required to ensure that fish meet required withdrawal times and are under the maximum residue limits in order to maintain markets in Canada and the US. Work will be completed winter 2010-2011 and results disseminated to pertinent regulatory authorities, industry and other interested parties.

Dec. 2010 – Mar. 2011 • Funded by: Department of Agriculture, Aquaculture and Fisheries of New Brunswick, Schering Plough/Intervet Animal Health, New Brunswick Total Development Fund
Project team: Mike Beattie (NBDAAF), Rob Merritt (NBDAAF), Bruce Thorpe (NBDAAF), Kathy Brewer-Dalton (NBDAAF), Jiselle Bakker (DFOSABS), Skretting, Cooke Aquaculture Inc.
Contact: Mike Beattie ( Mike.beattie@gnb.ca)

Evaluating transport and dispersal of chemical therapeutants: an oceanographic perspective

In the past couple of years, salmon growers in southwest New Brunswick have been using chemical therapeutants in bath and wellboat treatments to combat sea lice infestations. Once the salmon are exposed to the therapeutant for the prescribed time, the currently available treatment technologies release the chemical into the surrounding environment. Given that the chemicals are not specific to sea lice but target crustaceans in general, and that salmon farming is part of a complex multi-user environment, including local lobster and herring fisheries, characterizing the potential zone of influence of these treatments is integral for designing and applying appropriate management practices. Studies on the transport and dispersal of effluents from bath and wellboat treatments at multiple cage sites used fluorescent dye to track the effluent plumes. Fluorometry, visual plume perimeter estimations, time lapse imagery, and current profiles were used to observe the spatial extent of dye plumes and the temporal evolution of dye concentration within the plume. Water samples in the treatment cages and in the dye plume were collected and analyzed to develop dye-chemical relationships. Flushing of the dye from the treatment cages varied from minutes to hours and was likely influenced by net biofouling and current velocities. More data needs to be collected and existing data more fully analyzed to adequately describe the flushing plume characteristics from wellboats. The three dimensional distribution of the dye needs to be mapped to estimate the volume of exposure and be compared to local bathymetry to estimate the area of benthic exposure. Experiences to date indicate that individual site characteristics including depth, bathymetry, and current velocities play an important role in effluent transport and dispersal, and hence exposure. Gathered information will be coupled with toxicological studies led by Les Burridge (DFO), Bill Ernst (EC), and Ken Doe (EC) to assist in assessing the risk associated with these treatments.

Jun. 2010 – Mar. 2011 • Funded by: DFO – Program for Aquaculture Regulatory Research (PARR), DFO – Aquaculture Innovation and Market Access Program (AIMAP)
Project team: Fred Page (DFOSABS), Randy Losier (DFOSABS), Paul McCurdy (DFOSABS), Jack Fife (DFOSABS), Jiselle Bakker (DFOSABS), Blythe Chang (DFOSABS), Mike Beattie (NBDAAF), Bruce Thorpe (NBDAAF), Kathy Brewer-Dalton (NBDAAF)
Contact: Fred Page ( Fred.Page@dfo-mpo.gc.ca)

Adult female sea louse Lepeophtheirus salmonis

Hydrogen peroxide bath effects on salmon skin epithelium

Hydrogen peroxide is used widely for the treatment of sea lice by the salmon industry at the current time. Field sea lice counts seem to indicate that fish treated with hydrogen peroxide suffer from a higher copepodid-chalimus re-infestation than fish treated with other bath chemicals. Our hypothesis is that hydrogen peroxide may affect the ultrastructure of the skin epithelium and subsequently the composition of the mucous layer, thus making it easier for sea lice reattachment. Damage to the dermis from this treatment may also release semiochemicals or chemo-attractants causing sea lice to be overly "attracted" to these fish. If results are positive, industry must then consider adjusting the timing of the hydrogen peroxide treatments in order to reduce the chance of reinfestation. This adjustment would also lead to fewer treatments throughout the year.

Treated Atlantic Salmon

Jan. 2011 – Jan. 2012 • Funded by: Department of Agriculture, Aquaculture and Fisheries of New Brunswick, TDF, Novartis Animal Health Inc., AVC-UPEI
Project team:Mike Beattie (NBDAAF), Mark Fast (AVC-UPEI), Bruce Thorpe (NBDAAF), Kathy Brewer-Dalton (NBDAAF), Jiselle Bakker (DFOSABS), Jennifer Covello (AVC-UPEI), Sara Purcell (AVC-UPEI), Novartis Animal Health Inc.
Contact: Mike Beattie ( Mike.beattie@gnb.ca), Mark Fast ( mfast@upei.ca)

Construction and evaluation of a scale model of a finfish cage under different flow regimes simulating bath therapeutant exposure

The salmon farming industry in eastern Canada is examining novel therapeutants for sea lice control, as part of a broader Integrated Pest Management Strategy. These products are delivered as either in feed treatments or as bath treatments in cages using tarps or fully enclosed in well boats. Two questions for bath treatment usage are how rapidly the therapeutants diluted/dispersed following treatment in the cages, and what are the implications for non-target organisms within tarps and well boats and how they are transported and dispersed following release from these containers. A scale model circular cage system was constructed and tested in the world's largest laminar flume tank under differing flow regimes simulating conditions across Atlantic Canada salmon farming locations. Systems were tested under tarped and untarped conditions to simulate therapeutant explore flow through tarped and untarped cage exposure in the field. The results showed rapid dilution/dispersion of bath therapeutants in the top layers of the water column representing various growout conditions in eastern Canada. The corollary is that therapeutants are not expected to reach non-target organisms on the sea bed under normal treatment operating conditions. These findings are useful for helping design and interpret field studies and data. The work will help provide input into regulator decisions as well as help improve knowledge of flow patterns through cages which in turn will help improve husbandry processes. The flume tank observations complement ongoing field trials, and collectively help facilitate rapid and cost effective assessment of potential treatment procedures prior to undertaking field assessments.

Jan. 2010 – Mar. 2010 • Funded by: DFO – Aquaculture Collaborative Research and Development Program (ACRDP) Marine Institute of Memorial University (MUN)
Project team: Cyr Couturier (MUN), Fred Page (DFOSABS), Gehan Mabrouk (DFO)
Contact: Cyr Couturier ( cyr@mi.mun.ca) • http://www.mi.mun.ca/casd

Enhanced monitoring of sea lice using video technology

Regular and accurate sea lice counting is a vital part of sea lice control on salmon farms. However, the manual methods currently used are: time consuming; their accuracy is highly dependent on the skill of the human inspector; they require access to sea pens in increasingly exposed locations; and the crowding of fish to collect samples imposes additional stress on the fish. As a result, only a small number of fish can be sampled leading to problems with the statistical reliability of any population estimates. A passive, automated counting system offers the benefits of enhanced repeatability and accuracy, larger sample sizes, continuous monitoring, lower costs, and lower levels of disturbance for the fish. Such an approach, using underwater image capture and analysis techniques, was explored in a pilot study involving Scottish researchers in 2005-07. The success of this initial study has led to a follow-on innovation award under the Eurostars project VisuaLice E!4721.

The VisuaLice project builds on earlier work. It will trial precommercial equipment to validate this approach and calibrate the image capture and processing algorithms. These trials will take place in Scotland and Norway, with a research team that includes scientists and engineers from Iceland, England, and Canada. The Canadian involvement is mainly focused on the epidemiological interpretation of the data collected. The additional features and extensive nature of this data should better facilitate estimates of rates of population change, short term population variations, and enhance accuracy of prevalence estimation. The increased accuracy and temporal resolution provided by this novel approach will offer many benefits, including the ability to improve the timing and evaluation of treatment interventions, and achieve greater accuracy in the modeling of sea lice population dynamics.

Jan. 2010 – Jun. 2012 • Funded by: ACOA/AIF, Eurostars EU, FHF Norway
Project team: Jeff Lines (Silsoe Livestock Systems), Thorvaldur Petursson (Vaki Aquaculture Systems), Crawford Revie (UPEI), Gordon Ritchie (Marine Harvest ASA), Chris Wallace (Marine Harvest Scotland)
Contact: Crawford Revie ( crevie@upei.ca)

Colour inverted image of adult sea louse attached to a salmon fluorescing under ultraviolet illumination

Sea Lice Decision Support System (DSS)

The Sea Lice Decision Support System is a web-based application that allows users to enter, edit and review data and generate reports/graphs designed to assist those making treatment decisions associated with sea lice management on salmon farms. It is being developed by CAHS (AVC, UPEI) research scientists in collaboration with computer programmers. All data generated as part of both regular and targeted sea lice surveillance as well as all bioassay trial outputs are managed within the DSS. Once data are entered into the database, sea lice count summary reports and charts, as well as bioassay trial result graphs and reports are generated. Participating companies are able to access numerous summary charts associated with their sites as well as industry-wide averages.

Typical charts that are available by Bay Management Area (BMA) include: summaries of mean sea lice per fish, by sea lice stage; comparison of sea lice numbers with other sites over a given season or with respect to other production years, at various levels of aggregation; counting and treatment compliance reports to ensure coverage across the industry. Site-level charts are also available showing sea lice trends over time, by stage, allowing for an analysis of the efficacy of various treatment types. The ability is provided to drill down to detailed analysis of a treatment for a particular cage where pre and post–treatment sea lice levels by stage can then be used to assess the impact of any intervention over time.

In addition, all of the data and results from bioassays carried out on sites in New Brunswick are being stored in the DSS, with summary reports being available to farm management staff and prescribing veterinarians to aid in appropriate treatment selection. Because the DSS is web-based, the ability to assess bioassay result from sea lice treatments is also being offered to colleagues and researchers in other producing regions, which in turn could lead to AVC-CAHS becoming a global repository for this type of bioassay data.

Apr. 2010 – Mar. 2011 • Funded by: NB Dept. of Agriculture, Aquaculture and Fisheries (NBDAAF), ACOA-AIF, Atlantic Canada Fish Farmers Association (ACFFA)
Project team: Larry Hammell (UPEI), Crawford Revie (UPEI), Shona Whyte (UPEI), Jillian Westcott (UPEI), Holly Burnley (UPEI), Patti Jones (UPEI)
Contact: Larry Hammell ( lhammell@upei.ca)

Sea lice treatment monitoring in the Bay of Fundy, NB

A team of researchers from the Atlantic Veterinary College's Centre for Aquatic Health Sciences (AVC-CAHSUPEI) have been working closely with salmon farmers in Southern New Brunswick over the past year in a joint effort to monitor and combat the sea lice problems that have been hindering the salmon aquaculture industry. CAHS-driven activities include sea lice surveillance across the industry, training site staff in methods to conduct more accurate sea lice counts and the collection of sea lice from a range of sites to be used in laboratory bioassays. This comprehensive sea lice monitoring and management program is being funded through a collaboration among industry and governments.

CAHS technical staff conducted sea lice counts on many sites throughout 2010. While some routine weekly sea lice counts were conducted to monitor the effects of sea lice loads, most counts were carried out to monitor recently introduced sea lice treatments. Pre- and post-treatment sea lice counts were conducted on fish treated with SLICE®, Paramove®, AlphaMax®, Salmosan® and Ivermectin. Monitoring treatments in this way allows an assessment of the change in sea lice load on the salmon, which then helps determine the efficacy of the treatment. In addition to CAHS counts, sea lice counts done by farm staff are entered into an industry-wide decision support system for expanded sea lice and treatment response trend analysis.

These results are used to assist farms in making better treatment management decisions. Training on sea lice identification has been developed and offered by CAHS staff to industry multiple times, thus improving the ability to monitor sea lice at each developmental stage.

In addition to sea lice counts, our team has collected sea lice from numerous participating sites/companies for use in laboratory bioassays. Treatments that have been assessed in the lab include SLICE®, Salmosan® and Alphamax®. A graduate student within the Centre is developing a bioassay for hydrogen peroxide (i.e., Paramove) treatments in 2011. All bioassays are standardized using vigorous sea lice, counted into multiple petri dishes, and exposed to varying doses of a treatment. Length of exposure depends on the type of treatment being used. After a 24-hour period, sea lice in every dish are observed and condition/rigour is recorded. Once analysis is complete, the efficacy of the treatment can be determined based on the number of sea lice that survive treatments at different doses.

Apr. 2010 – Mar. 2011 • Funded by: NB Dept. of Agriculture, Aquaculture and Fisheries (NBDAAF), ACOA-AIF, Atlantic Canada Fish Farmers Association (ACFFA)
Project team: Larry Hammell (UPEI), Crawford Revie (UPEI), Shona Whyte (UPEI), Jillian Westcott (UPEI), Holly Burnley (UPEI), Patti Jones (UPEI)
Contact: Larry Hammell ( lhammell@upei.ca)

Better ways to apply bath treatments to control sea lice

A range of techniques exist with which to carry out bath treatments on salmon farms. These include the use of tarpaulins as 'skirts' (draped around each cage) or, preferably, pulled under the cage to provide a complete enclosure, as well as the increased use of well boats. In addition, the advent of 'super-size' cages able to hold at least a quarter of a million fish located in more exposed settings has led managers and scientists to question the nature of optimal treatment strategies for topical approaches. Of particular interest is the establishment of appropriate sampling methods to evaluate different types of topical intervention. This question is being explored as part of an international research project.

The TopiLouse project involves a number of Norwegian partners, including fish farming and pharmaceutical companies and well boat manufacturers, in addition to academic researchers from Norway, Scotland and Canada. The overall goal of this multi-disciplinary team is to improve the effectiveness of topical treatments used in sea lice control. A particular focus of the team at UPEI will be the examination of sampling and surveillance protocols associated with adequate sampling in modern fish farm environments. This will include a range of field sampling activities in both Norway and Canada involving intensive, farm-wide sea lice counting (e.g., sampling up to 100 fish from all cages on a site). These unique data sets will be analyzed using a simulation and mathematical modeling platform to provide guidance on how best to organize sea lice surveillance in the future.

Apr. 2010 – Sept. 2012 • Funded by: Research Council of Norway, ACOA/AIF
Project team: George Gettinby (University of Strathclyde), Peter Andreas Heuch (Norwegian Veterinary Institute), Crawford Revie (UPEI)
Contact: Crawford Revie ( crevie@upei.ca)