Transcript New growing pattern

Development of a multi-species model in the
Bay of Biscay using the modelling
environment GADGET
Workshop on
“Ecosystem Based Fisheries Management –
State of the Art”
Eider Andonegi
27th of March of 2008, Esbjerg (Denmark)
Structure
• 1. Introduction:
– 1.1. Ecosystem approach to fisheries: modelling approaches
– 1.2. GADGET
– 1.3. Bay of Biscay
• 2. Status of the art:
– 2.1. Single-species model for hake
 Gadget – VPA results comparison.
 Predictions (Recovery Plan for European Hake)
 New growing pattern (de Pontual et al. 2006)
– 2.2. Single-species model for anchovy
– 2.3. Preliminary multi-species model (hake eating on anchovy)
 Traditional - new growing pattern.
• 3. Things to do
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1.1. Introduction: Modelling approaches
• Ecosystem approach to fisheries (Plagányi, 2007)
– Whole ecosystem models (ECOSIM-ECOPATH-ECOSPACE,
bioenergetic/allometric models…)
– Dynamic multi-species models or Minimun Realistic Models
(MSVPA, MSFOR, GADGET, MRM…)
– Dynamic System Models (OSMOSE, INVITRO, ATLANTIS…)
– Extensions of single-species assessment models: ESAM.
• MRM- shared characteristics:
– they are system specific;
– only a small selected component of the ecosystem is modelled
– lower trophic levels and primary production are modelled as
constant or varying stochastically.
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1.2. Introduction: GADGET(www.hafro.is/gadget)
-Globally applicable Area
Disaggregated General Ecosystem
Toolbox.
- To model marine ecosystems,
including both the impact of the
interactions between species and
the impact of fisheries harvesting
the species.
- Three parts:
•a parametric model to simulate the
ecosystem
•statistical functions to compare the
model output to data
•search algorithms to optimize the
model parameters
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1.3. Introduction: Bay of Biscay
•
Extends from 48ºN to 43ºN and from 11ºW
to the coastlines of France
and North-western Spain.
8º
10°
4º
6º
49º
VIIj
2°W
0°
2° E
4º
VIIe
VIIh
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VIIIa
24
Lances con
bycatch
año 2003
47º
VIIId
20
45°
•
Biogeographically the region
corresponds to a subtropical/boreal
transition zone (from Finisterre to Brittany)
VIIIb
16
200 m
43º
IXa
D9
14
E1
E3
E5
E7
Ecological richness of the region (topographical diversity)
•
Why GADGET?
–
–
–
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VIIIc
•
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22
E9
F1
F3
Two commercially important species in the Bay of Biscay : European hake (Merluccius
merluccius) and European anchovy (Engraulius encrasicolus).
Bay of Biscay is considered a not really rich area concerning to the amount of data available
New literature on ecosystems and diet of target species in the area (Mahe, 2007; Velasco,
2007)
Participation in two relevant European projects BECAUSE(http://www1.uni-hamburg.de/BECAUSE) and
UNCOVER (http://www.uncover.eu) (help from Iceland and Norway).
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2.1.a. Status of the art: a single-species model for
European hake
– HAKE (Northern Stock): main predator in the BoB

Merluccius merluccius, Linnaeus 1758

Currently available data (BoB):
–
–
–
–
–
W-L relationship from real data
Von Bertalanffy parameters
Survey data: EVHOE (gaps in 1991,1993,1996)
Commercial data: Basque & French (from 1987 to 2003)
Maturity ogives coming from the WGHMM.
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2.1.b. Status of the art: a single-species model for
European hake. GADGET-VPA results
•First length-based model in the area which
avoids the current assessment problems
(i.e. uncertainty on the hake growth pattern)
•A total of 35 parameters have been
estimated (8 for the initial population, 17 for
the recruitment and 10 for the selectivity
pattern). Growth parameters have been
fixed.
•Most recent information for this stock is
shown in the last report of the assessment
WGHMM (ICES, 2006).
• A summary of the most important
parameters of this stock is represented in
this figure, both from the new model and
from the XSA.
•Most significant differences in the results of
the compared models are shown in the last
picture of this figure, the number of recruits.
These differences could give us an idea
about the recruitment spatial pattern of
this species in this area.
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2.1.c. Status of the art: a single-species model for
European hake. Predictions (Recovery Plan)
•Predictions (from 2004 to
2015)
•Parameters:
• F´= meanF (last
3years)*constant (0.1, 0.2,
0.3, 0.4, 0.5, 0.6, 0.7, 0.8,
0.9)
•Reruits = average number
of the last three years
•Results:
•SSB upper the
precautionary limit always.
•Similar to the WGHMM
results
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2.1.d. Status of the art: a single-species model for
European hake. New growing pattern
• Testing the new growing
pattern given by the sampling
experiments carried out during
the last years in the area (de
Pontual et al., 2006).
• Preliminary results, need to be
studied in more detail.
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2.2. Status of the art: a single-species model for
anchovy
–
ANCHOVY: relevant prey specially for hakes < 30 cm in the
BoB (Mahe et al. 2007)

Engraulis encrasicolus, Linnaeus 1758

Currently available data (only BoB):
–
–
–
–

W-L relationship from real data
Von Bertalanffy parameters
Survey data: EVHOE (gaps in 1991,1993,1996), DMPH, PELGAS.
Commercial data: Basque & French ones from ICES WGMHSA (1987
to 2003)
No reasonable results. Working on problems.
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2.3.a Status of the art: preliminary multi-species
model (hake eating anchovy)
•
Consumption is not dependant
neither on predator nor on prey
lengths. It has been
implemented following a
constant suitability function.
•
It is well known that this
assumption is not realistic as
there is a relationship between
consumption and size of the
preys.
•
However, more time is needed
to implement this relatioship in
the model from the availble
data.
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2.3.b Status of the art: preliminary multi-species
model (hake eating anchovy). New growing pattern
Summary plots
• Testing the new growing
patters (de Pontual et al.,
2006)
• Results to study carefully in
more detail.
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3. Things to do
• Improve the current models :
– fit the anchovy model to the available data in a reasonable way
– implement the new data on ecosystem and diet for Hake in this area to
work hard on the multi-species model.
– Introduce new target species (preys) as Horse Mackerel (Trachurus
trachurus, Linnaeus 1758), Blue Whiting (Micromesistius poutassou,
Risso 1826), Sardine (Sardina pilchardus, Walbaum 1792) and
cannibalism effects…
• Introduce new maturation ogives obtained from the recently finished
European project RASER.
• Try to extend the model for the whole area covered by the real
stock.
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References
• de Pontual, H., Groison, A.L., Pineiro, C. and Bertignac, M., 2006.
Evidence of underestimation of European hake growth in the Bay of
Biscay, and its relationship with bias in the agreed method of age
estimation. ICES J. Mar. Sci., 63:1674-1681.
• ICES, 2006. Report of the Working Group on the Assessment of
Southern Shelf Stocks of Hake, Monk and Megrim (WGHMM). ICES
CM 2006/ACFM:29:792 pp.
• Mahe, K., Amara, R., Bryckaert, T., Kacher, M., and Brylinski, J. M.
2007. Ontogenetic and spatial variation in the diet of hake
(Merluccius merluccius) in the Bay of Biscay and the Celtic Sea.
ICES Journal of Marine Science, 64: 1210–1219.
• Plagányi, É. E. 2007. Models for an ecosystem approach to
fisheries. FAO Fisheries Technical Paper. No. 477. Rome, FAO. 108
pp.
• Velasco, F., 2007. Alimentación de la merluza europea (Merluccius
merluccius L.) en el mar Cantábrico. PhD Thesis.
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