Biosecurity and Fish Health Management for Recirculating Systems

Biosecurity and Fish Health Management for Recirculating Systems
Julie Bebak‐Williams, VMD, PhD
Freshwater Institute Shepherdstown, WV
1
Why are infectious disease outbreaks more likely to
occur in the RAS?
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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
2
Why does it matter (costs)?
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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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Running a facility without a biosecurity and fish health management plan will
result in these costs when an infectious disease outbreak occurs.
Note also that the higher capital and production costs of recirculating
systems means that the consequences of infectious disease outbreaks can
be catastrophic.
3
What is biosecurity?
4
Biosecurity
Hazard reduction through
environmental manipulation
(Plumb, 1992)
(Operating costs are reduced by minimizing the number and severity
of disease outbreaks.)
Biosecurity accomplishes hazard reduction through environmental
manipulation.
Biosecurity cannot completely prevent entry of, or eliminate, all pathogens
from a culture facility.
Biosecurity accomplished pathogen reduction rather than pathogen
elimination.
5
Effective Biosecurity
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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)
6
What is one strategy for
“making up” for losses?
Add extra fish.
7
100,000 at Start
Pathogen Dose
Starting Fish Density
<0.11
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
Can we compensate for losses to infectious disease by adding more fish to
the system? No.
Numbers in cells of table are the number of fish left at the end of an outbreak
for a given starting fish density and pathogen dose.
If we start with 100,000 fish, we have fewer left over at the end of the
outbreak in the higher fish densities for a given pathogen dose (and higher
pathogen doses for a given fish density)
8
Death rate (%/day)
Effect of Pathogen Dose
16
14
12
10
1 Inf
2 Inf
3 Inf
All Inf
0 Inf
8
6
4
2
0
0
5
10
15 20 25
30 35 40 45
50 55 60
Time (days)
Example from an experiment evaluating the relationship between fish density
and pathogen dose. This graph shows what happens to the death rate when
the pathogen dose increases from 0 to 1,2,3 or all infectious fish added to
varying densities of susceptible fish. The value for the death rate peaks
gradually higher at 5.2, 5.9, 6.2 and 14.9 %/day for 1, 2, 3 and All Inf,
respectively. The peak death rate occurs earlier and earlier 26, 25, 24 and
13 days for 1, 2, 3 and All Inf, respectively.
9
Rule of Thumb
Every producer that transports fish directly from a
pond into a recirculating system will experience
catastrophic losses from infectious disease
outbreaks
10
Opportunistic vs. Obligate Pathogens
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Obligate pathogens
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Require animal host to replicate
Viruses (IPNV, IHNV, VHSV and OMV in salmonids); bacteria (bacterial
(bacterial kidney
disease, furunculosis?,
furunculosis?, enteric redmouth disease)
Opportunistic pathogens
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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 gastrogastrointestinal tract)
Includes the species associated with bacterial gill disease, coldwater
coldwater disease,
columnaris disease, and the motile aeromonads.
aeromonads. Opportunistic parasites include
Trichodina,
Trichodina, Chilodonella,
Chilodonella, Ichthyobodo?
Ichthyobodo?, Epistylis and Ambiphyra.
Ambiphyra. The fungi can also be
considered opportunistic pathogens.
11
Biosecurity planning starts at the facility design
stage
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Includes consideration of
„ Placement of doors
„ Placement of disinfection areas
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Ventilation – to control insects, dust and aerosol transfer
(also can use barriers)
12
Facility design
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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
13
Circular Tanks & Solids Removal
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Advantages:
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self cleaning
rapid solids fractionation
uniform environment
optimum rotational velocity
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for swimming fish
flow distributes feed & fish
Solids fractionation – rapidly moving settleable solids to center drain so they don’t
move out of side drain – leaves tank in 1 to 2 minutes and 5 minutes in a 30 foot
tank
Create uniform environment as far as mixing, equal DO, Co2 ammonia
Optimal rotational velocity – 0.5 to 2.0 body lengths per second (12-30 cm/sec)
compared to raceway which is much lower than 0.5 (2-4 cm/sec)
Flow distributes feed and fish more evenly around the tank
14
Circular Tanks w/o Rotation
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Solids must be “mucked-out” of tank.
15
Design features should be easy and
convenient to use
White River NFH
Top of CO2 stripper at White River NFH
Designed by Brian, 8 feet diameter
Constructed of panels with handles that are easy to remove and easier to clean, can
do while in operation
16
Clean Outs and Cone-bottom Unit Processes
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Solids should not build up in any
part of system:
system:
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Easy to clean
Unit processes (CO2 stripper, LHO,
biofilter) designed to be cleaned
(e.g., conecone-bottom, ability to drain)
Include features to ease solids
removal from system (e.g., clean
outs)
Example of a cleanout – very important!
17
Clean-Outs for Ozone Contacting
13-40 min O3
Destruct
6-20 min O3
Contact
ozonated inlet
Stripping
Column
Fan
sediment
trap
sediment
trap
to culture tanks
Foam & O3
Off-Gas
Separator
Floor drain
Lamar NFH (PA)
Note also cone-shaped unit processes that facilitates collection and emptying.
18
Clean-Out Locations in all Sumps
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CO2 & O2 Control
cascade
aeration
column
(Summerfelt et al., 2000)
LHO
Note the clean outs in the LHO sump and the CO2 stripper
From the LHO sump to the fish tanks. An example of how you can take a unit
process off line.
19
Isolation of system components
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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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20
Bypass Piping
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Drain piping should be
plumbed to allow drum
filter bypass to direct
flow to:
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drum filter
pump sump
Drain (away from RAS)
„ during
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cleaning events
Pump sump
„ When
filter
servicing drum
drain
21
Bypass Piping
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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
22
Sump Design
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Sump design with no standing water
White River Nat’l Fish Hatchery
Sump on left side doesn’t drain, would be better if it slopes and collects to a drain
Properly sized pipes move solids away from the system, used to be 8”, but now 4”.
Dam boards were present with the 8” pipes, moved out dam boards and replaced
with 4 inch so the whole thing drained more efficiently
Solids will settle where there are dead zones and low velocity pipes so removed
dead zones and increased velocity to remove solids
23
Fish health monitoring allows early detection
of a problem
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Tank windows
Two locations
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where healthiest fish would be
where sick fish would
congregate
24
Mort Removal
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Design features to remove dead fish
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“Mort Flush”
Flush”
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Quantify mortality
Reduce pathogen load on system
Remove weak/moribund fish for examination
25
Unit processes in separate building
White River NFH
26
Avoid use of wood, unless disposable
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Equipment used for
sequential cohorts
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PVC sheets instead of wood
sheets
27
Metal
28
Plastic
Inexpensive & Easy to Disinfect
29
I. Practices to Reduce the Risk of
Pathogen Introduction
30
Water Supply
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Specific-pathogen free (SPF) groundwater supply
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For both well and spring water
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Investigate possibility of surface water input (depends on surrounding
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
31
Eggs and Fish
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Specific-pathogen-free certified eggs/fish
Eggs disinfected upon arrival
Quarantine new fish, certified or not
Avoid introduction of delivery water
32
Feed
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Live food
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Presents a serious risk of contamination with pathogens -should be
cultured as specificspecific-pathogenpathogen-free, never used directly from the
natural environment
Commercial dry feeds
SteamSteam-pelleted – 160160-180 F (71(71-82 C)
„ Expanded – 180180-200 F (82(82-93 C)
„ Extruded – 220220-350 F (104(104-177 C)
Lyophilized feed
„ Many microorganisms survive lyophilization well
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33
People Management
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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
34
People Management (cont.)
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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
35
Visitor Control
Can use signs, rope and cones to control visitor and personnel movement
36
People Management (cont.)
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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
37
Footbath
Incorrect use of a footbath – dirty boots and footbath is almost dry.
Footwear going in should be clean and foot bath solution should be clean
and at least one to two inches above the top of the material in the footbath
38
Quarantine
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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
39
Quarantine (cont.)
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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
40
Quarantine (cont.)
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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
41
II. Practices to Reduce Pathogen Spread
42
Meticulous husbandry
An example of a dirty system
43
Husbandry
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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)
44
Disinfection area
Three sink method: First sink for dirty equipment and for hand washing,
second sink has disinfect and third sink is for rinsing disinfected equipment
only
Trash cans: One has disinfectant, the other is the rinse, with constant flow of
water through it
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Husbandry (cont.)
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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 crosscontamination
Disinfect tanks and equipment before use with a
different group of fish
46
Husbandry (cont.)
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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
47
Definitions
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Surfactant – 'SURFace ACTive AgeNT'
AgeNT' - a molecule that lowers suface
tension; contain both hydrophobic and hydrophilic components so are
semisemi-soluble in both organic and aqueous solvents; the hydrophobic
component sticks to grease and dirt while the hydrophilic section
section sticks to
the water; active ingredient in soap
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Disinfectant – eliminates virtually all recognized pathogenic
microorganisms; an agent that kills or inactivates >99.99% of disease
disease
causing microorganisms, may not kill spores
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Sanitizer – an agent that decreases the load of microorganisms (not
necessarily pathogenic)
48
Surfactant Example
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“Simple Green”
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Cleaner and degreaser
Listed as nonhazardous, nonnon-mutagenic, nonnon-carcinogenic
On a scale of 1 to 4, ranked as 1 for slight health hazard because
because it can
be a mild eye irritant (mucous membrane irritation concentrate mist)
mist)
No special ventilation is required during use
Meets EPA and OECD recommendations for ready biodegradability;
practically nonnon-toxic per EPA’
EPA’s aquatic toxicity scale
Components on TSCA Chemical Substance Inventory
OECD – Organization for Economic Cooperation and Development
49
Disinfectants
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Factors affecting disinfection process
Type
„ Concentration
„ Temperature
„ Contact Time
„ pH
„ Presence of soil/organic matter
„ Number of organisms
„ Type and growth phase of organism
„
50
Iodophor
Broad spectrum (inactivates IPNV)? No
Inactivated by soil/organic matter?
Yes, but turns yellow & is more stable than chlorine
NonNon-toxic fish?
Depends on dilution
NonNon-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
51
Quaternary Ammonium Compounds (QACs)
Broad spectrum (inactivates
IPNV)?
Inactivated by soil/organic
matter?
NonNon-toxic fish?
NonNon-toxic humans?
Corrosive?
Surfactant activity?
Leaves active residue?
Stable?
Tests for active chemical
residues?
Safe for environment
No
Moderately stable
Depends on dilution
Corrosive to skin and eyes; Irritation of respiratory
tract; headache, drowsiness
No
Yes
Yes
Yes
Test strips
Regs
52
Hypochlorite (HTH)
Broad spectrum (inactivates
IPNV)?
Inactivated by soil/organic
matter?
NonNon-toxic fish?
NonNon-toxic humans?
Corrosive?
Surfactant activity?
Leaves active residue?
Stable?
Tests for active chemical
residues?
Safe for environment
Yes
Yes
Extremely toxic at low concentrations
Dust causes skin, eye, digestive tract and respiratory burns
Yes, to metals and plastics
V. slight
No
No, dissipates rapidly
Test strips
Regs (must be neutralized with sodium thiosulfate)
53
Virkon-S
(potassium monopersulfate)
Broad spectrum (inactivates
IPNV)?
Inactivated by soil/organic
matter?
NonNon-toxic fish?
NonNon-toxic humans?
Corrosive?
Surfactant activity?
Leaves active residue?
Stable?
Tests for active chemical
residues?
Safe for environment
Yes
?
Depends on dilution
As powder can be respiratory and eye irritant
To metals but not netting
Yes (including bacterial biofilms)
?
Dissipates very slowly
?
Regs.,
Regs., breaks down to harmless organic salt
54
Culling
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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
55
Additional Strategies
„ Changing
flow to increase turnover rates
„ Density manipulation
56
Culture Activities
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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
57
III. Practices to Reduce Susceptibility to
Infection and Disease
58
Strategies for a Strong Immune System
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Optimum nutrition
Fish should be from
optimum year class brood
stock
Gentle handling to reduce
stress and injury
Vaccination
59
IV. Monitoring
Set up a monitoring
and response plan
60
Record Keeping
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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
61
Monitor Water Quality!
62
Know normal vs. abnormal behavioral and
physical signs for stress and illness
63
Behavioral and Physical Signs for
Stress/Illness
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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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64
Behavioral and Physical Signs for
Stress/Illness
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Feeding
Not feeding
„ Reduced feeding (detected by system TAN and growth
curves as well as observation)
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Breathing
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Decreased or increased rate of opercular movement
65
Behavioral and Physical Signs for Stress/Illness
Physical Condition
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Visible lesions or sores
Cloudy eyes, protruding eyes
Gills swollen, white, pink or
pale red, eroded, puffy,
bloody, brown
Scale loss
Swollen abdomen
Diarrhea
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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
66
Submersible Biomass Scanner
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VAKI DNG (Kópavogur,
Iceland)
Used to track Arctic char size & growth at CFFI.
What principle does the VAKI scanner work on? Infrared diode array note the
contour of the fish to get shape profile from top and side – works at 100 kg/m3
67
V. Diagnosis
68
Supplies/Equipment for Fish Health
Laboratory
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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))
69
Diagnosis
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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
70
Diagnosis
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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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71
Treatment
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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
72
Case Study #1
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Recirculating salmonid facility
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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
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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)
73
Case Study #1 (cont.)
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Recommendations
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Fungi growing on solids substrates, so system maintenance is overdue
overdue
– it’
it’s time to get into the cleanouts and get the solids out of the
system, also, use formalin to treat affected fish.
„
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Some of the clean outs were not installed, others were concreted in. As a result,
needed to try to access the pipes from hardhard-toto-reach areas – continually coping
with chronic, lowlow-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”
shipping” – they are now disinfecting eggs upon arrival
74
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
„
75
Current/Future Issues in Biosecurity of
Recirculating Systems
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The safety of “disease-free” ground water supplies
Opportunistic pathogens present in recirculating
systems that come from the fish or from the
environment
76
Biosecurity programs should
be dynamic, re-evaluate and
change as necessary
77