Monte Carlo Simulations and Sensitivity Analyses
as a Means to Assess and Optimize the Design of
Integrated Multi-Trophic Aquaculture Sites
Palisade workshop,
Miami, FL
October 25
G.K. Reid1,2, S.M.C. Robinson2, T Chopin1, Mullen J. 1,2, T. Lander1,2, M.
Sawhney1, B. MacDonald1, K. Haya2, L. Burridge2, F. Page2, N. Ridler1, S.
Boyne-Travis3, J. Sewuster4, M. Szemerda5, F. Powell5 and R. Marvin5
1
University of New Brunswick, Centre for Coastal Studies & Aquaculture, Centre for Environmental &
Molecular Algal Research, P.O. Box 5050, Saint John, NB
2
Department of Fisheries & Oceans, 531 Brandy Cove Road, St. Andrews, NB
3
Canadian Food Inspection Agency, 99 Mount Pleasant Road, St. George, NB
4
Acadian Seaplants Limited, 30 Brown Avenue, Dartmouth, NS
5
Cooke Aquaculture Inc., 14 Magaguadavic Drive, St. George, NB
Modern Intensive Salmon
Aquaculture
• Almost half of the food fish supplies in the
world are now from aquaculture
•Intensive salmon aquaculture is a small fraction of
this, but generates the most publicity
•One of the criticisms of intensive cage based
aquaculture is environmental impacts from the
nutrient load …ah, that is “fish pooh and pee”
Potential Impacts below
salmon cages
In conditions of low flushing:
- Low oxygen may occur giving rise to
sulfur oxidizing bacterium (Beggiatoa)
- A local loss of biodiversity and high
quality energy
BUT ….. Highly Localized and Temporary
Also water column impacts
• Algal blooms (eutrophication) Æ oxygen
loss as they die and decompose
• More of an issue in freshwaters
• What is a limiting nutrient and who cares?
– NitrogenÆ Marine
– Phosphorus Æ Freshwater
• Both are loaded from fish culture
What can we do to minimize
nutrient loading Impacts?
• Model to ensure nutrient loading stays
within the assimilative capacity of the
localized ecosystem
• Monitor to identify and respond to negative
impacts
• Recover some of the ‘lost nutrients’ in
harvestable biomass
• Combination of the above
The thing about nutrients…
•Essential for life Æ appropriate
concentrations
•When present in excess Æ becomes a
pollutant
•Back to fish cages
Lobster Boat
Salmon Cage
Hmmmm?
Now, what is IMTA
• Integrated Multi-Trophic Aquaculture (IMTA) is a
practice in which the by-products (wastes) from
one species are recycled to become inputs
(fertilizers, food) for another
• Fed aquaculture (e.g. fish) is combined with
inorganic extractive (e.g. seaweed) and organic
extractive (e.g. shellfish) aquaculture to create
balanced systems for environmental
sustainability (biomitigation), economic stability
(product diversification and risk reduction) and
social acceptability (better management
practices)
Transition from Pilot Project to
Commercial Scale
• A five year IMTA pilot project involving industry, academia
and government partners has recently been completed in
the Bay of Fundy
• The pilot phase clearly indicated the plausibility and
potential of IMTA, and consequently this has lead to a
second phase, the transition of IMTA to a commercial
scale
• One if the biggest challenges is the determination of
optimal culture densities, placements and species
diversity at commercial scales
• These commercial scale IMTA sites are evolving largely
through trial and error, mainly due to site design issues
and the learning of new husbandry techniques
The Overall IMTA Model: Schematic Overview
Revenue ? Æ Production required Æ Scale Æ Placement Æ OptimalÆ Costs
Ammonia,
Phosphate
O2
CO2
O2
CO2
Particulates
?
es
t
lth
a
He ality
Qu
O2
Other species
CO2
Disease transfer/mitigation ?
Predation? Contaminants ?
h
alt ty
e
H ali
Qu
O2
CO2
Solids
Solids
Flushing rate, re-supply,
removal, hydrodynamics
temperature, water quality,
carrying & assimilative capacity
lth
a
He ality
Qu
Se
ed
Ha
rv
Ha
rv
lth
a
He ality
Qu
$
es
t
Fe
ed
es
t
Se
ed
Stock
$
$
$
Ha
rv
$
$
$
Mussel sock culture
Kelp Photo
Kelp Harvest
Photos courtesy of Manav
Sawhney and Thierry
Chopin
So when do we get to the
Palisade software?
Soon, but first something really cool !
IMTA site fly-through
We have questions?
But do we have answers?
• How do we optimize the design of an
IMTA site?
• How do we know if we are recovering any
nutrients?
• We do have data on the accelerated
growth rates of mussels and kelp grown
beside salmon cages
• How much nutrients are captured in the
‘augmented growth’?
It is the Biomass Ratios that are Important, not the
Scale of any One Component
If the total
combined
biomass is
the same for
both
examples
High inorganic
(soluble) nutrient
recovery
Low inorganic
(soluble) nutrient
recovery
Hypothetical IMTA Site Schematic:
Spatial Considerations
Kelp
Mussels
Boat access side
Fish Cages
What is the optimal ratio of rafts to fish cages?
Boat access needed for harvest. How does this affect placement?
Can not infinitely scale up co-cultured species rafts without
increase in fish cage numbers
Vertical Scale
‘Trial and Error’
Availability of salmon nutrients for
co-cultured species
Soluble
(~20%)
Solids (~80%)
Fecal solids & waste feed
Available to
Mytilus edulis
(blue mussels) ?
Deposit feeders
(worms, urchins,
sea cucumbers,
etc.)
Ammonia &
Phosphate
Other
inorganic
extractive
species
(seaweeds
/plants)
Available to
Saccharina
latissima
(seaweed)
Modeling Approaches
• Due to a combination of natural effects and site
management necessities, conducting traditional
scientific experimentation, where all variables are
controlled except the one of interest, is practically
impossible
•Nevertheless we need to model the system to
determine optimal design parameters and provide
data for coastal zone management
•How is this accomplished in the midst of
unpredictable dynamic change
Modelling Approaches Continued
Some modelling approaches
like Monte Carlo simulation,
can generate a likelihood of
outcomes based on ‘partial
data’ thereby providing
practical estimates until
validation can occur at fully
evolved commercial sites
But First…
The nutritional massbalance model ,proper
Salmonid Nutrient Mass Balance
Available to Inorganic
Extractive Species
Introduced feed
Available to Organic
Extractive Species
Retained
Digested nutrients
Ingested
Nutrients
Nutrients in
Waste Feed
Indigestible nutrients
Fin
es
Soluble Nutrients
Fecal nutrients
Non & slow-settleable
particulates
Settles out
Near-field
advection
Dissolves in
water column
Amount and Composition of Faeces
from a Typical Commercial Feed
Feed
(100 kg)
Percent
Digestion
40
95%
29
90%
26.1
2.9
Carbohydrates 17.6
2.5
Minerals
60%
10.6
7.0
50%
1.3
1.3
Phosphorus
1.5
50%
0.8
0.8
Moisture
9.4
50%
Total
100
Protein
Lipids
Digested
(kg)
Faeces (kg)
38.0
2.0
?
76
14
~14 kg of ‘dry’ faeces produced
from 100kg feed consumed
Estimation of soluble nutrient load from Atlantic
salmon consuming a typical Atlantic salmon feed
(from 100 kg feed consumed)
Feed
composition
(%)
39
1.2
Protein
Phosphorus
Digestibility
(%)
Amount
digested
(%)
Carcass
composition
(%)
90
50
35
0.60
18
0.55
Considered the soluble nutrients
If 83 kg growth occur
from 100kg feed
(1.2 FCR), the
amount retained
Not retained
(%)
Nitrogen
(%)
Protein
14.9
20.2
3.23
Phosphorus
0.46
0.14
Input values are not static Æ
“Enter the Distribution”
Some example distributions:
• Digestibility of nutritional components
• Mass ratios (feed, feces, ‘fines’)
• What is in the feed?
• What is the critter (or seaweed) or body
composition
• Proportion of faeces that are settleable vs.
suspended
– This seems silly but is extremely important
How we’re using @RISK
1) Fit your input distributions
2) Identify your outputs
3) Run the simulation
And then tell it like it is
The ‘Quick Report’ is
Your Friend!
The Awesome Tornado Diagram !
Dry salmon fecal matter output is sensitive to these inputs
Dry matter theoretically available to mussels (i.e. 5for DryMT
Matter
Theoretical
120Distribution
µm) from 2000
salmon
feed input
Availablitiy of ...
0.040
Mean=27.18287
0.035
0.030
0.025
0.020
0.015
0.010
0.005
0.000
0
14
5%
12.8228
28
42
90%
56
5%
44.5228
70
Theoretical Availability of Total Organic
Aquaculture Solids for Blue Mussels (MT)
?
Regression Sensitivity for Cell H72
Aquaculture solids 5 -120 µm/E45
NFE in feed/E19
Protein in feed/B19
.866
.327
.172
Protein digestibility (sal.../B24
.118
.105
NFE digestibility (salmon).../E24
Lipids digestiblity (salmo.../D24
.087
.042
Minerals digestibility (sa.../F24
.025
.015
Phosphours disgestibility .../G24
.013
-.133
Minerals in feed/F19
Fines / waste feed ratio/B41
-.09
-.088
Waste feed/D14
Lipids in feed/D19
-.037
Percent fines 5 -120 µm/E41
Phosphorus in feed/G19
-.015
Economic FCR/C14
-1
-0.75
-0.5
-0.25
0
0.25
Std b Coefficients
0.5
0.75
1
If we run a simulation to estimate nutrient recovery
and vary the biomass
1000-3000 MT
Feed Input
100-400 MT
100 -250 MT
Data sets from our pilot project
Growth Increase
of Kelp grown beside
salmon farms
0.59
0.27
0.48
0.24
0.19
0.46
0.44
0.24
Growth Increase
of Mussels grown
beside salmon farms
0.534
0.449
0.273
0.235
0.193
0.373
0.239
Fitting distribution to mussel growth
attributable to a fish farm (GAFF)
Nutrient Recovery of
Co-cultured Mussels
Recovery of solid nutrients:
Dry matter ~ 2.6%
Solid (organic) nitrogen ~5%
Solid (organic) phosphorus ~ 0.8%
Frequency
Regression sensitivity for dry matter recovery
Mussel Dry Matter
Recovery Distribution
%
Kelp Nutrient Recovery
•Total Nitrogen Recovery ~ 2.5%
•Almost 40% of what could be recovered under this
culture regimen
Regression sensitivity for nitrogen recovery
Frequency
Kelp nitrogen recovery
distribution
Enter the Deposit Feeders
These results show deposit feeders are what’s needed
to tackle the bulk of the nutrient waste
What we learn from modeling exercises
•All species must be practically accessible for husbandry and
harvest
•Co-cultured species must have more than good nutrient
‘capture ability’
•They must be able to digest and convert ‘lost nutrients’ to
biomass
•We must consider how all species functions together as an
ecosystem
•We need to ensure that addition of co-cultured species
results in a net increase of nutrient recovery
•We need to be able to model the ‘nutrient and energy
cascades’ to ensure this
Lessons continued
• It is not possible to report a general ‘mitigation’ or
nutrient recovery value for an IMTA system
• Nutrient recovery efficiency is a function of the
number and diversity of co-cultured species
• Each co-cultured species will have its own ‘niche’
and cannot exploit nutrients beyond this ‘niche’
• The aformentioned challenges cannot be
thoroughly anticipated or studied in laboratory or
pilot scale projects and, consequently,
emphasizes the need for scientific research and
commercial development to progress in a
concerted manner
A final ‘plug’
See our IMTA project featured on an
upcoming National Geographic
episode of ‘Strange Days on Planet
Earth’
Questions?
Thanks to our partners