Biosecurity and Fish Health Management for Recirculating Systems

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Biosecurity and Fish Health Management for
Recirculating Systems

• Julie Bebak-Williams, VMD, PhD
• Freshwater Institute
• Shepherdstown, WV

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Why are infectious disease outbreaks more likely
to occur in the RAS?

• Fish loading densities greater than those used in
  pond or serial reuse systems
• Continuous production strategies
• Prolonged water retention in system provides
  extended residence time that allows for growth of
  opportunistic and overtly virulent pathogens
• Relatively more stressful environment

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Why does it matter (costs)?

• Costs
• Diagnosis, response, diversion of management and
  labor, underutilization of production facility
• Direct losses from mortality
• Reduced quality of survivors
• Inability to replace stock
• Restricted market for healthy stock because of
  damage to reputation and missed markets
• Restriction of movement orders
• Facility closure orders

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What is biosecurity?
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Hazard reduction through environmental
manipulation
Biosecurity
(Plumb, 1992)
(Operating costs are reduced by minimizing the
number and severity of disease outbreaks.)
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Effective Biosecurity

• Reduces risk of pathogen introduction
• Reduces risk that pathogens will spread
  throughout the facility
• Reduces conditions that increase susceptibility
  to infection and disease (e.g., reduce stress)

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What is one strategy for making up for losses?
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100,000 at Start
Starting Fish Density
lt0.11 lbs/gal 0.11-0.21 lbs/gal 0.22-0.34 lbs/gal
1 Inf 76,062 31,595 25,790
2 Inf 37,389 27,449 24,488
3 Inf 26,703 30,201 22,466
Pathogen Dose
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Effect of Pathogen Dose
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Rule of Thumb

• Every producer that transports fish directly from
  a pond into a recirculating system will
  experience catastrophic losses from infectious
  disease outbreaks

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Opportunistic vs. Obligate Pathogens

• Obligate pathogens
• Require animal host to replicate
• Viruses (IPNV, IHNV, VHSV and OMV in salmonids)
  bacteria (bacterial kidney disease,
  furunculosis?, enteric redmouth disease)
• Opportunistic pathogens
• Do not require animal host to replicate
  nutrition from organic material
• Naturally occur in soil and water
• May also be part of the natural microbial
  population in the fish (e.g., the
  gastro-intestinal tract)
• Includes the species associated with bacterial
  gill disease, coldwater disease, columnaris
  disease, and the motile aeromonads.
  Opportunistic parasites include Trichodina,
  Chilodonella, Ichthyobodo?, Epistylis and
  Ambiphyra. The fungi can also be considered
  opportunistic pathogens.

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Biosecurity planning starts at the facility
design stage

• Includes consideration of
• Placement of doors
• Placement of disinfection areas
• Ventilation to control insects, dust and
  aerosol transfer (also can use barriers)

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Facility design

• Reduce noise and vibration
• Arrange tanks so that they are easily accessible
• Ability to take individual tanks and unit
  processes off line for cleaning or chemical
  treatment
• Construction materials non-porous and easy to
  clean and disinfect (plastic, metal, PVC)
• Avoid use of wood (consider disposable)
• Never transfer equipment to or from another site

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Circular Tanks Solids Removal

• Advantages
• self cleaning
• rapid solids fractionation
• uniform environment
• optimum rotational velocity
• for swimming fish
• flow distributes feed fish

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Circular Tanks w/o Rotation

• Solids must be mucked-out of tank.

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Design features should be easy and convenient to
use
White River NFH
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Clean Outs and Cone-bottom Unit Processes

• Solids should not build up in any part of system
• Easy to clean
• Unit processes (CO2 stripper, LHO, biofilter)
  designed to be cleaned (e.g., cone-bottom,
  ability to drain)
• Include features to ease solids removal from
  system (e.g., clean outs)

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Clean-Outs for Ozone Contacting
Lamar NFH (PA)
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Clean-Out Locations in all Sumps
cascade aeration column

• CO2 O2 Control
• (Summerfelt et al., 2000)

LHO
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Isolation of system components

• Tanks and unit processes that can be taken off
  line drained out of system
• For cleaning while the rest of the system is
  operating, then discharge out of the system
• For chemical treatment of individual tanks,
  discharge to a chemical drain

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Bypass Piping

• Drain piping should be plumbed to allow drum
  filter bypass to direct flow to
• Drain (away from RAS)
• during cleaning events
• Pump sump
• When servicing drum filter

drum filter
pump sump
drain
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Bypass Piping

• Clean-outs with valves were installed at the end
  of every pipe run.
• Discharge tank pipe cleaning flows into floor
  trench.

MCRA Hatchery, Delbarton, WV
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Sump Design

• Sump design with no standing water

White River Natl Fish Hatchery
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Fish health monitoring allows early detection of
a problem

• Tank windows
• Two locations
• where healthiest fish would be
• where sick fish would congregate

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Mort Removal

• Design features to remove dead fish
• Mort Flush
• Quantify mortality
• Reduce pathogen load on system
• Remove weak/moribund fish for examination

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Unit processes in separate building
White River NFH
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Avoid use of wood, unless disposable

• Equipment used for sequential cohorts
• PVC sheets instead of wood sheets

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Metal
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PlasticInexpensive Easy to Disinfect
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I. Practices to Reduce the Risk of Pathogen
Introduction
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Water Supply

• Specific-pathogen free (SPF) groundwater supply
• For both well and spring water
• Investigate possibility of surface water input
  (depends on surrounding geology and depth
• Test both before purchase of the property
• Should be constructed to protect from surface
  water input and entry of animals (e.g.,
  invertebrates, amphibians, reptiles, mammals,
  birds) that could be carriers of pathogens
• If surface water must be used, then it must be
  disinfected

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Eggs and Fish

• Specific-pathogen-free certified eggs/fish
• Eggs disinfected upon arrival
• Quarantine new fish, certified or not
• Avoid introduction of delivery water

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Feed

• Live food
• Presents a serious risk of contamination with
  pathogens -should be cultured as
  specific-pathogen-free, never used directly from
  the natural environment
• Commercial dry feeds
• Steam-pelleted 160-180 F (71-82 C)
• Expanded 180-200 F (82-93 C)
• Extruded 220-350 F (104-177 C)
• Lyophilized feed
• Many microorganisms survive lyophilization well

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People Management

• Frequent washing of hands and arms with
  antibacterial soap should be standard practice
• Strategically schedule culture activities (work
  on most vulnerable stages first, minimize number
  of personnel working on a group of fish, leave
  sick for last)
• Disinfect vehicles before driving up to facility

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People Management (cont.)

• Visitor parking at periphery of facility grounds
• Restrict facility access to a minimum number of
  people
• Minimize number of tours and limit to small,
  easily managed groups
• Maintain log book
• Visitors (not at aquaculture facility w/in past
  48 hours) coveralls over clothing, disinfected
  boots, wash with antibacterial soap for 30 seconds

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Visitor Control
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People Management (cont.)

• Visitors (at aquaculture facility w/in past 48
  hours) remove clothes, put on coveralls and
  disinfected boots, wash with antibacterial soap
• Instruct visitors not to touch, or lean on,
  anything in culture room
• Change footbaths and disinfect floors after every
  tour

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Footbath
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Quarantine

• Planned early in the design of the facility
• Separate building, room or area with independent,
  isolated culture system
• Q period accounts for incubation and development
  times for targeted pathogens
• Water temperature kept at upper end of fish
  species optimum range to speed up pathogen life
  cycles

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Quarantine (cont.)

• Observe new arrivals for abnormalities in
  appearance and behavior, sample and examine
• Throughout Q period, sample normal and abnormal
  fish, examine
• Hold fish at culture densities they will
  encounter in production system

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Quarantine (cont.)

• Wash hands and arms before going between
  quarantine and production area. Disinfect
  footware. Change clothing.
• Save work in Q area as last element of the work
  day
• Use Q equipment only in the Q area
• Acclimate fish to production system water by
  introducing it to quarantine before transfer out
  of quarantine

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II. Practices to Reduce Pathogen Spread
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Meticulous husbandry
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Husbandry

• Install deep foot baths, clean and change
  frequently
• Wash hands and arms before entering fish culture
  area and as change work with groups of fish
• Easily accessible disinfectant and rinse areas
  (e.g., for buckets, nets, meters)

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Disinfection area
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Husbandry (cont.)

• Store clean equipment in a clean area
• Meticulous husbandry procedures
• Even for recycle loop, treat each tank as a
  discrete rearing unit, minimize potential for
  cross-contamination
• Disinfect tanks and equipment before use with a
  different group of fish

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Husbandry (cont.)

• Regard floor as contaminated, manage accordingly
• Clean floors frequently
• Inspect and clean all parts of system frequently
• Exclude pets, rodents, birds, other vertebrates
  and insects from culture area

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Definitions

• Surfactant 'SURFace ACTive AgeNT' - a molecule
  that lowers suface tension contain both
  hydrophobic and hydrophilic components so are
  semi-soluble in both organic and aqueous
  solvents the hydrophobic component sticks to
  grease and dirt while the hydrophilic section
  sticks to the water active ingredient in soap
• Disinfectant eliminates virtually all
  recognized pathogenic microorganisms an agent
  that kills or inactivates gt99.99 of disease
  causing microorganisms, may not kill spores
• Sanitizer an agent that decreases the load of
  microorganisms (not necessarily pathogenic)

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Surfactant Example

• Simple Green
• Cleaner and degreaser
• Listed as nonhazardous, non-mutagenic,
  non-carcinogenic
• On a scale of 1 to 4, ranked as 1 for slight
  health hazard because it can be a mild eye
  irritant (mucous membrane irritation concentrate
  mist)
• No special ventilation is required during use
• Meets EPA and OECD recommendations for ready
  biodegradability practically non-toxic per EPAs
  aquatic toxicity scale
• Components on TSCA Chemical Substance Inventory

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Disinfectants

• Factors affecting disinfection process
• Type
• Concentration
• Temperature
• Contact Time
• pH
• Presence of soil/organic matter
• Number of organisms
• Type and growth phase of organism

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Iodophor
Broad spectrum (inactivates IPNV)? No
Inactivated by soil/organic matter? Yes, but turns yellow is more stable than chlorine
Non-toxic fish? Depends on dilution
Non-toxic humans? Skin and eye irritation
Corrosive? Slightly
Surfactant activity? No
Leaves active residue? Yes
Stable? Dissipates slowly
Tests for active chemical residues? Test strips
Safe for environment Regs
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Quaternary Ammonium Compounds (QACs)
Broad spectrum (inactivates IPNV)? No
Inactivated by soil/organic matter? Moderately stable
Non-toxic fish? Depends on dilution
Non-toxic humans? Corrosive to skin and eyes Irritation of respiratory tract headache, drowsiness
Corrosive? No
Surfactant activity? Yes
Leaves active residue? Yes
Stable? Yes
Tests for active chemical residues? Test strips
Safe for environment Regs
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Hypochlorite (HTH)
Broad spectrum (inactivates IPNV)? Yes
Inactivated by soil/organic matter? Yes
Non-toxic fish? Extremely toxic at low concentrations
Non-toxic humans? Dust causes skin, eye, digestive tract and respiratory burns
Corrosive? Yes, to metals and plastics
Surfactant activity? V. slight
Leaves active residue? No
Stable? No, dissipates rapidly
Tests for active chemical residues? Test strips
Safe for environment Regs (must be neutralized with sodium thiosulfate)
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Virkon-S(potassium monopersulfate)
Broad spectrum (inactivates IPNV)? Yes
Inactivated by soil/organic matter? ?
Non-toxic fish? Depends on dilution
Non-toxic humans? As powder can be respiratory and eye irritant
Corrosive? To metals but not netting
Surfactant activity? Yes (including bacterial biofilms)
Leaves active residue? ?
Stable? Dissipates very slowly
Tests for active chemical residues? ?
Safe for environment Regs., breaks down to harmless organic salt
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Culling

• An important strategy to reduce transmission of
  pathogens
• Should include sick (as long as cause is
  infectious) as well as dead fish
• Cull at least once per day
• Fish should be killed humanely, not allowed to
  die from suffocation

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Additional Strategies

• Changing flow to increase turnover rates
• Density manipulation

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Culture Activities

• Minimize the number of different personnel
  working with a group of fish
• Unaffected tanks should be worked on before
  affected tanks
• Care for young fish before older fish
• Equipment touching the floor should not contact
  fish culture water
• Fish that jump from tank to floor should be
  humanely killed, not returned to tank

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III. Practices to Reduce Susceptibility to
Infection and Disease
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Strategies for a Strong Immune System

• Optimum nutrition
• Fish should be from optimum year class brood
  stock
• Gentle handling to reduce stress and injury
• Vaccination

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IV. Monitoring

• Set up a monitoring and response plan

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Record Keeping

• Used to track changes
• Used to improve biosecurity protocols
• Includes water quality, feed fed, feed lot
  numbers, visitors, number of dead and culled
  fish, observations of abnormalities, laboratory
  results, results of treatment

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Monitor Water Quality!
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Know normal vs. abnormal behavioral and physical
signs for stress and illness
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Behavioral and Physical Signs for Stress/Illness

• Movement
• Weak, erratic, lethargic swimming
• Abnormal reaction to external stimuli such as
  noise or movement
• Scratching, flashing, rubbing against tank walls
  or bottom
• Twitching, darting, spinning or jumping out of
  water
• Crowding at inflent water supply
• Swimming upside down
• Gasping at water surface

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Behavioral and Physical Signs for Stress/Illness

• Feeding
• Not feeding
• Reduced feeding (detected by system TAN and
  growth curves as well as observation)
• Breathing
• Decreased or increased rate of opercular movement

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Behavioral and Physical Signs for
Stress/IllnessPhysical Condition

• Visible lesions or sores
• Cloudy eyes, protruding eyes
• Gills swollen, white, pink or pale red, eroded,
  puffy, bloody, brown
• Scale loss
• Swollen abdomen
• Diarrhea

• Excess mucus on skin/gills (check for excess
  mucus on tank screens)
• Spots, fungus on skin
• Unusual coloration on body surface
• Flared opercula
• Frayed fins or tail
• Bubbles in eyes, skin, gills

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Submersible Biomass Scanner

• VAKI DNG (Kópavogur, Iceland)

Used to track Arctic char size growth at CFFI.
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V. Diagnosis
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Supplies/Equipment for Fish Health Laboratory

• Compound microscope (with 10X ocular and 4X, 10X,
  and 40X objectives)
• Slides, cover slips
• Dissecting kit (for large and small fish)
• Anesthetic (e.g., tricaine methane sulfonate
  (MS-222))

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Diagnosis

• Keep accurate records so that an accurate history
  can be compiled
• Learn normal and abnormal appearance and behavior
• Evaluate water quality
• Learn skin scrape and gill biopsy techniques to
  identify parasites
• Find an aquaculture veterinarian

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Diagnosis

• An accurate diagnosis is essential
• Determines treatment regimen (whether, and which,
  chemotherapeutants should be used)
• Treatment based on hunches results in wasted time
  and money and further degradation of the fish
• Incorrect diagnosis prevents development of an
  effective strategy to prevent recurrence

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Treatment

• Disease from water quality more likely in a
  biosecure recirculating system (slow turnover
  rate)
• If chemical treatment is necessary, effect on
  biofilter must be considered (Table 13.3) (design
  system for biofilter bypass during treatment)
• When treating the whole system, slow turnover
  rate means chemical might need to be applied at a
  lower concentration for a longer period
• Take individual tanks off-line for bath or
  flow-through treatment

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Case Study 1

• Recirculating salmonid facility
• Specific-pathogen-free eggs
• Biosecurity recommendations included disinfection
  of eggs with iodophor upon arrival from supplier
• Specific-pathogen-free water supply
• Design criteria included clean outs
• Attention to biosecurity appeared to be excellent
  but after one year, saw system-wide fungal
  infections and upon routine inspection fish were
  infected with Aeromonas salmonicida (furunculosis)

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Case Study 1 (cont.)

• Recommendations
• Fungi growing on solids substrates, so system
  maintenance is overdue its time to get into
  the cleanouts and get the solids out of the
  system, also, use formalin to treat affected
  fish.
• Some of the clean outs were not installed, others
  were concreted in. As a result, needed to try to
  access the pipes from hard-to-reach areas
  continually coping with chronic, low-level fungal
  infections in the system install cleanouts
  after system built
• Regarding the furunculosis bacteria
  recommendations to disinfect eggs upon arrival
  were not followed because the supplier
  disinfected them before shipping they are now
  disinfecting eggs upon arrival

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Case Study 2 (or, if we do everything you say,
will we experience disease outbreaks?)

• FI research system a biosecure system
• Spring water supply
• No infectious disease problems except chronic,
  recurring respiratory disease
• A new pathogen chlamydia-like/rickettsia-like
  bacteria that infects gill cells
• Identification of organism, development of
  prevention and control strategies are in progress

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Current/Future Issues in Biosecurity of
Recirculating Systems

• The safety of disease-free ground water
  supplies
• Opportunistic pathogens present in recirculating
  systems that come from the fish or from the
  environment

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Biosecurity programs should be dynamic,
re-evaluate and change as necessary