1. Ecopath can incorporate 150+ functional groups and 40+ fisheries
Conservation
Biomass ‘pools’
Tropic Level
Trophic links

2. Mass balance: cutting the pie
Other
mortality
Harvest
Unassi-
milated
food
Predation
Harvest
Respi-
ration
Respi-
ration
Predation
Predation
Other mortality
Unassi-
milated
food
Consumption
Other mortality
Unassi-
milated
food
Predation
Predation
Respi-
ration

3. INTRO 1 Ecopath An Introduction (1) 1.Mass-balance models Ecopath
Defining the components of model
Obtaining parameters of ecosystem functional groups
Diet matrix
Including fishery sectors and catches in
the model
Model construction
Balancing the model
Diagnosing the model
Semi-Bayesian estimation (Ecoranger)
Mass-balance ecosystem models (Ecopath 4).
Components of model. Obtaining parameters of ecosystem functional groups. Diet matrix. Model construction. Balancing the model. Semi-Bayesian estimation (Ecoranger). Including fishery sectors and catches in the model.
Simulations and “what if?” scenarios (Ecosim)
Tropho-dynamic simulations using Ecosim. Split pools and recruitment. Limitations of the Ecosim technique – ecological interactions covered by Ecosim. Seasonal changes. Links between models.
Spatial simulations of exploited ecosystems (Ecospace)
Movement parameters of Ecopath groups. Substrate, production and habitat parameters. Modelling and design of marine protected areas using Ecospace.
Reconstruction of past ecosystems: “Back to the Future”.
Rebuilding and trade-offs to provide guidelines for ecosystem management. Incorporation of archival, archeological and TEK data on past ecosystems. Evaluation of benefits to society (Ecoval).
Rapid appraisal of fisheries: (Rapfish)
Multi-disciplinary, non-parametric, rapid appraisal of fisheries using ecological, technological, economic, social, ethical and ecosystem evaluation fields. Application to FAO Code of Conduct for Responsible Fisheries. Ordination method, mathematical basis, temporal trajectories, leverage analysis, Monte Carlo simulations and uncertainty, presentation of results.
An Introduction (1)

4. Defining the ecosystem
OPTIMAL CRITERIA
Use natural ecological boundaries
CONSTRAINTS
Use reporting areas for fish catches ( landings )
Political boundaries may have to be used

5. Ecosystem: Odum’s definition
“any entity or natural unit that includes living and nonliving parts interacting to produce a stable system in which the exchange of materials between the living and nonliving parts follows circular paths is an ecological system or ecosystem. The ecosystem is the largest functional unit in ecology, since it includes both organisms (biotic communities) and abiotic environment, each influencing the properties of the other and both necessary for maintenance of life as we have it on the earth. A lake is an example of an ecosystem.”
Odum, E.P (1953) Fundamentals of Ecology
B u t … b e r e a l i s t i c …… !

6. INTRO 1 Ecopath An Introduction (1) 1.Mass-balance models Ecopath
Defining the components of model
Obtaining parameters of ecosystem functional groups
Diet matrix
Including fishery sectors and catches in
the model
Model construction
Balancing the model
Diagnosing the model
Semi-Bayesian estimation (Ecoranger)
Mass-balance ecosystem models (Ecopath 4).
Components of model. Obtaining parameters of ecosystem functional groups. Diet matrix. Model construction. Balancing the model. Semi-Bayesian estimation (Ecoranger). Including fishery sectors and catches in the model.
Simulations and “what if?” scenarios (Ecosim)
Tropho-dynamic simulations using Ecosim. Split pools and recruitment. Limitations of the Ecosim technique – ecological interactions covered by Ecosim. Seasonal changes. Links between models.
Spatial simulations of exploited ecosystems (Ecospace)
Movement parameters of Ecopath groups. Substrate, production and habitat parameters. Modelling and design of marine protected areas using Ecospace.
Reconstruction of past ecosystems: “Back to the Future”.
Rebuilding and trade-offs to provide guidelines for ecosystem management. Incorporation of archival, archeological and TEK data on past ecosystems. Evaluation of benefits to society (Ecoval).
Rapid appraisal of fisheries: (Rapfish)
Multi-disciplinary, non-parametric, rapid appraisal of fisheries using ecological, technological, economic, social, ethical and ecosystem evaluation fields. Application to FAO Code of Conduct for Responsible Fisheries. Ordination method, mathematical basis, temporal trajectories, leverage analysis, Monte Carlo simulations and uncertainty, presentation of results.
An Introduction (1)

7. B Mass-balance - Ecopath Biomass pools Production/Biomass — P/B
Consumpt./Biomass
— Q/B
Ecotrophic efficiency
Diet matrix
Adjusted to mass-
balance
[Production of i] – [all predation on i] – [non predation losses of i] – [export of i] = 0
Christensen, V. and Pauly, D. (1992) The ECOPATH II - a software for balancing steady-state ecosystem models and calculating network characteristics. Ecological Modelling 61:
Polovina, J.J. (1984) Model of a coral reef ecosystem. Part I: the ECOPATH model and its application to French Frigate Shoal. Coral Reefs 3: 1-11.
Christensen, V. and Pauly, D. (1992) The ECOPATH II - a software for balancing steady-state ecosystem models and calculating network characteristics. Ecological Modelling 61:
Polovina, J.J. (1984) Model of a coral reef ecosystem. Part I: the ECOPATH model and its application to French Frigate Shoal. Coral Reefs 3: 1-11.

8. Ecopath mass-balance equation
How
much
is there
of what
eats them?
is there?
is used
in system?
important
is it in
their diet?
more
this year?
gets
caught?
do they
eat?
Bi * (P/B)i * EEi = Yi +  Bj * (Q/B)j * DCji
Production ( group i)
Consumption (by group j)

9. Defining the ecosystem groups
Functional ecological groupings
Ecological similarities (niche overlap)
rather than taxonomy to aggregate species
Aggregate using cluster analysis on parameters
Include groups needed for policy analysis
(fisheries, conservation)
Groups where data available
Do not omit a known group
for lack of data – its worse than using guesstimates
Include all trophic levels
Care with bacteria and microbial loop
One (or more) must be a detritus group

10. Ecopath master equation 1
Production = biomass accumulation
+ predation
+ fishery
+ net migration
+ other mortality

11. Ecopath master equation
Bi * P/Bi * EE i = Catch i
+  Bj *(Q/B)j * DC ji
+ Export i
Most common inputs:
B, P/B, Q/B, Catch, diet (DC) so EE is estimated
Balancing:
DC’s modified to ensure EE’s are  1.
How it is implemented

12. Estimations in Ecopath models
For each group, your data in green,
program estimates those in red. e.g.
1) B, P/B, Q/B, EE, DCs, ...
2) B, P/B, Q/B, EE, DCs, ...
3) B, P/B, Q/B, EE, DCs, ...
4) B, P/B, Q/B, EE, DCs, ...
Ranked ease of estimation:
P/B and Q/B > B > DCs >> EE
hence EE often left unknown (Option 1 above)

13. Data requirements Key Data Requirements Biomass (t·km-2)
Production / Biomass (ratio year-1)
Consumption / Biomass (ratio year-1)
Ecotrophic Efficiency (proportion)
Diets (DC) (proportion)
Catches (by fleet) (t·km-2 ·year-1)
Economic data
Ranges possible (Monte Carlo routines)

14. Open a model (File menu)
Files are stored in Microsoft Access format
Set up an .mdb file for each model ecosystem

15. Model information

16. Group information
Click a group name

17. Double-click mouse to enter remarks
Entering Remarks
Double-click mouse to enter remarks
Remarks possible - groups and output
Cells with remarks are highlighted
Use Ecowrite to extract remarks

18. Basic input

19. Basic parameterization (II)
Basic input

20. Biomass Example from standard assessment methodologies
don’t travel well, local information is important
Time
Biomass
Example

21. A case for making 3 models
Period 1
Period 2
Period 3
Time
Biomass
Example

22. INTRO 1 Ecopath An Introduction (1) 1.Mass-balance models Ecopath
Defining the components of model
Obtaining parameters of ecosystem functional groups
Diet matrix
Including fishery sectors and catches in
the model
Model construction
Balancing the model
Diagnosing the model
Semi-Bayesian estimation (Ecoranger)
Mass-balance ecosystem models (Ecopath 4).
Components of model. Obtaining parameters of ecosystem functional groups. Diet matrix. Model construction. Balancing the model. Semi-Bayesian estimation (Ecoranger). Including fishery sectors and catches in the model.
Simulations and “what if?” scenarios (Ecosim)
Tropho-dynamic simulations using Ecosim. Split pools and recruitment. Limitations of the Ecosim technique – ecological interactions covered by Ecosim. Seasonal changes. Links between models.
Spatial simulations of exploited ecosystems (Ecospace)
Movement parameters of Ecopath groups. Substrate, production and habitat parameters. Modelling and design of marine protected areas using Ecospace.
Reconstruction of past ecosystems: “Back to the Future”.
Rebuilding and trade-offs to provide guidelines for ecosystem management. Incorporation of archival, archeological and TEK data on past ecosystems. Evaluation of benefits to society (Ecoval).
Rapid appraisal of fisheries: (Rapfish)
Multi-disciplinary, non-parametric, rapid appraisal of fisheries using ecological, technological, economic, social, ethical and ecosystem evaluation fields. Application to FAO Code of Conduct for Responsible Fisheries. Ordination method, mathematical basis, temporal trajectories, leverage analysis, Monte Carlo simulations and uncertainty, presentation of results.
An Introduction (1)

23. Diet compositions Tuna Example Use volume or weight! Auxids 1.7%
Partly digested fish 31.6%
Others 19.3%
Portunids 15.8%
Euphausiids 3.5%
Squids 12.3%
Anchovies 8.8%
Sardines 7%
Auxids 1.7%
Use volume or weight!

24. Estimation of diet compositions
Diet compositions are often species-specific, and may need averaging. Use weighted averages;
It is often necessary to modify the diet compositions to balance the model.
‘Import’ is feeding on prey groups that are not explicitly included in the ecosystem;
Example: If marine mammals in a model of the near-surface open ocean feed on mesopelagics in the Deep Scattering Layer, then treat the mesopelagics as import

25. Diet composition entry

26. INTRO 1 Ecopath An Introduction (1) 1.Mass-balance models Ecopath
Defining the components of model
Obtaining parameters of ecosystem functional groups
Diet matrix
Including fishery sectors and catches in
the model
Model construction
Balancing the model
Diagnosing the model
Semi-Bayesian estimation (Ecoranger)
Mass-balance ecosystem models (Ecopath 4).
Components of model. Obtaining parameters of ecosystem functional groups. Diet matrix. Model construction. Balancing the model. Semi-Bayesian estimation (Ecoranger). Including fishery sectors and catches in the model.
Simulations and “what if?” scenarios (Ecosim)
Tropho-dynamic simulations using Ecosim. Split pools and recruitment. Limitations of the Ecosim technique – ecological interactions covered by Ecosim. Seasonal changes. Links between models.
Spatial simulations of exploited ecosystems (Ecospace)
Movement parameters of Ecopath groups. Substrate, production and habitat parameters. Modelling and design of marine protected areas using Ecospace.
Reconstruction of past ecosystems: “Back to the Future”.
Rebuilding and trade-offs to provide guidelines for ecosystem management. Incorporation of archival, archeological and TEK data on past ecosystems. Evaluation of benefits to society (Ecoval).
Rapid appraisal of fisheries: (Rapfish)
Multi-disciplinary, non-parametric, rapid appraisal of fisheries using ecological, technological, economic, social, ethical and ecosystem evaluation fields. Application to FAO Code of Conduct for Responsible Fisheries. Ordination method, mathematical basis, temporal trajectories, leverage analysis, Monte Carlo simulations and uncertainty, presentation of results.
An Introduction (1)

27. Fisheries data
It is possible to include any number of fleets (or gears);
Parameters for each
variable costs
fixed costs
market prices
landings
discards
fate of discards

28. Fishery: any number of fleets

29. Landings
The landings (exclusive of discards) should be entered as rates (t · km-2 ·year-1)
Landings with no cash value should be treated as landings (set price to 0), not as discards,
which are fed back to the system

30. Entering landings, discards, prices

31. Market prices Non-market values
Fleet-specific prices for each group that is harvested;
Default value is 1 for all groups for all fleets.
Non-market values
‘Existence’ values can be considered, e.g., the value for tourism of having, e.g., marine mammals in a system;
Default value is 0.

32. Fleet-specific prices for all harvested groups
Cost of fishing
Fixed value of operating each gear can be entered (monetary currency per time unit)
Variable cost is entered as relative to the effort in the Ecopath model
Spatial fishing costs may be entered in Ecospace
Any monetary currency can be used as unit
Only simple bio- economic analyses are included
Fleet-specific prices for all harvested groups

33. Discards are entered as rates t · km-2 ·year-1
Discard fate
For fisheries with discards it is advisable to have a detritus group called, e.g., ‘dead fish’
Direct the fishery discards to this group
Make scavengers feed on it
NOTE: ‘Dead fish’ are of higher nutritional value than most other detritus (such as excreta from zooplankton)
Discards are entered as rates t · km-2 ·year-1

34. Existence values
‘Existence’ values can be considered, e.g., the value for tourism of having marine mammals or large groupers in a system
Default value is 0

35. ECOPATH 2 Ecopath An Introduction (2) 1.Mass-balance models Ecopath
Defining the components of model
Obtaining parameters of ecosystem functional groups
Diet matrix
Including fishery sectors and catches in the model
Model construction
Balancing the model
Diagnosing the model
Semi-Bayesian estimation (Ecoranger)
Mass-balance ecosystem models (Ecopath 4).
Components of model. Obtaining parameters of ecosystem functional groups. Diet matrix. Model construction. Balancing the model. Semi-Bayesian estimation (Ecoranger). Including fishery sectors and catches in the model.
Simulations and “what if?” scenarios (Ecosim)
Tropho-dynamic simulations using Ecosim. Split pools and recruitment. Limitations of the Ecosim technique – ecological interactions covered by Ecosim. Seasonal changes. Links between models.
Spatial simulations of exploited ecosystems (Ecospace)
Movement parameters of Ecopath groups. Substrate, production and habitat parameters. Modelling and design of marine protected areas using Ecospace.
Reconstruction of past ecosystems: “Back to the Future”.
Rebuilding and trade-offs to provide guidelines for ecosystem management. Incorporation of archival, archeological and TEK data on past ecosystems. Evaluation of benefits to society (Ecoval).
Rapid appraisal of fisheries: (Rapfish)
Multi-disciplinary, non-parametric, rapid appraisal of fisheries using ecological, technological, economic, social, ethical and ecosystem evaluation fields. Application to FAO Code of Conduct for Responsible Fisheries. Ordination method, mathematical basis, temporal trajectories, leverage analysis, Monte Carlo simulations and uncertainty, presentation of results.
An Introduction (2)

36. Top predators are special
They help constrain the parameter ranges for others

37. Life history shifts of diet
Split top predator groups:
adult and juvenile sub-groups capture diet shifts
Later …… Ecosim simulations will be more realistic

38. This makes Ecospace simulations more realistic later
Use of habitat area
Example
Biomass in lagoon t / km2
Biomass elsewhere t / km2
Lagoon area km2
Total area km2
Input Biomass : t / km2
Habitat area : 0.04
i.e. 1/25 of total area
This makes Ecospace simulations more realistic later

39. P/B - Production/Biomass
= Z
From catch composition data using standard stock assessment methodologies
Natural mortality of fish from Pauly’s (1980) empirical equation:
M = K0.65 · L∞ ·T0.463
F = catch / biomass
P/B = Z = F + M
P/B = K(L∞-Lavg)/(Lavg-L’) [B&H57]

40. Food consumption (Q/B)
Growth (VBGF)
Biomass (B)
Q/B
Wt = W·(1-e-K(t-t0))b t
Food consumption (Q)
Mortality t
Nt = R·e-M(t-tr)
K1 (Gross food conversion) t t t

41. Food consumption Welcome to Maxim’s
Tilapia
Lake Awasa, Ethiopia
L = 23 cm, W = 265 g 12 16 20 24 04
Time (h)
End of feeding
Start of feeding

42. Q/B Food consumption - a tail story
The faster swimming
fish eats more

43. Q/B Food consumption - a tail story
Yellow
Aspect ratio, AR :
Red
AR = 9.8
AR = 1.3
Q/B = 3 · W-0.2 · T0.6 · AR0.5 · 3 eFt
W = asymptotic weight
T = temperature
AR = aspect ratio
Ft = foodtype (0 f. carn.)

44. Q/B Food consumption: a tail story
When not to use it
Only for symmetrical tails used for propulsion

45. P/C Production / Consumption gross food conversion efficiency
Production and Consumption ratios are related for a given population
If exploitation changes, the production (mortality) rate will change, and so will the consumption
The P/C ratio is more conservative than either of the two rates individually

46. Niche: prey overlap

47. Niche overlap
Each point shows overlap between a pair of groups

48. Niche overlap Each point shows overlap between a pair of groups
Same predators different prey
Each point shows overlap between a pair of groups

49. Niche overlap Same predators different prey
Each of these two pairs has similar prey and predators
Same prey different predators
No overlap

50. Ecotrophic efficiency (EE)
EE is the proportion of the production that is used in the system (for predation or export)
1-EE is ‘other mortality’
Best to let Ecopath estimate EE
For most groups EE  <=1,
exception, examples
phytoplankton bloom EE  0.5
kelps EE’s  0.1
unexploited top predators EE  0
“Small pelagics don’t die of old age”.

51. Other input for Ecopath models
For living groups
Biomass accumulation rate
Assimilation %*
Diet compositions
Net migration rate
Detritus fate
For fleets
Landings
Discards
Discard fate
Fixed cost of fishing
Variable cost
Market price by fleet and group
Existence value
Jobs
*Default values : 20% for non-assimilated, 0 for others

52. Biomass accumulation (Bacc)
Ecopath is not a steady-state model, biomasses can change over time
Bacc is entered as rates ( t · km-2 ·year-1)
Default 0, has been used in nearly all models
Use Bacc if you have data showing change in biomass at start and end of the period to be modeled
If B, P/B, Q/B and EE are entered for a group, the program will offer to estimate Bacc
If Bacc values are non-zero, Ecosim will show change over time even without any change in fishing

53. Ecopath master equation 2
Consumption = production
+ unassimilated food
+ respiration

54. Non-assimilated food (U)
Remember the Ecopath Master Equation (II):
Q = P + R + U
Q and P are estimated first
Respiration (R) is then calculated as
R = (Q - P) - U i.e.; changing U only impacts R
The default value of 20% for U is generally acceptable, except for herbivores and detritivores where 40% leads to more reasonable R/B ratios.

55. Migration Immigration and Emigration are rates (t·km-2 ·year-1)
Net migration enters into the production equation (Master Equation I)
Migration is also used by Ecosim & Ecospace

56. Migration

57. Detritus fate
At least one detritus group is required. It must be entered after the living groups on the Ecopath input form
All living groups produce detritus, from
excretion and egestion, and from ‘other
mortality’
Possible Ecopath Groups
POM
DOM
Discarded_fish
It is therefore necessary to specify to which detritus group the detritus generated by a living group is directed

58. Detritus fate

59. Alternative input
Per convention, respiration is calculated, not an input From the second Ecopath Master Equation respiration is calculated as
Respiration = consumption - production - unassimilated food
An alternative form for input is ….
…… any of the terms in the second Master Equation,
or some ratios based on these terms
The standard input for Ecopath is then calculated

60. Alternative input

61. Key Ecopath routines
Ecopath routines for entry of key data on the biology and exploitation of ecosystem groups, and for establishing mass-balance
FishBase bridge ( established for input data
Econet: network analysis for study of ecosystem form and functioning, incl. particle size distribution (PSD);
Ecowrite routine for documentation of data and assumptions used when constructing and validating models. Incorporates reference database.
Ecoempire module with empirical relationships

62. Ecopath includes extended help
F1 key for help