Transcript Diapositiva 1

7. EAF tools for the analysis of
exploited ecosystems in the
Mediterranean:
c) Ecosystem indicators
Dr Sergi Tudela, WWF Mediterranean Programme Office
Salammbô, Tunisia, 7-9 September 2005
SCMEE Workshop on Ecosystem Approach to Fisheries
In its strongest form, EBFM is understood as arising
from a change of paradigm:
•Fisheries deal with the use/exploitation of whole ecosystems
•Ecosystems are complex entities
•There is an important amount of inherent uncertainty related
to the knowledge of and predictions on ecosystems
•A new precautionary ecosystem-based
approach for fisheries is needed
management
•Under this conceptual framework, there is no room for
reductionist, ecosystem-engineering approaches failing to
incorporate the underlying systemic paradigm
from Tudela & Short (2005)
Some immediate management implications:
•Management must look for more holistic solutions,
accounting for uncertainty.
•Classic TROM is of course useful and necessary, but always
under a more general EBM context. In fact, some
redundancy in management measures is intrinsically a
precautionary approach.
•A precautionary EBM to Fisheries must be adaptive (trial and
error approaches are needed).
•New tools are needed for both research and management.
•The real danger of an excess of parameterization needs
should be avoided: the development of new data-poor
(adaptive and precautionary) approaches is essential.
•Our predicting expectations from science must somewhat
change: we must learn on how to work with qualitative
information
from Tudela & Short (2005)
Some immediate management implications:
•Under an EBM approach both concepts conservation and
fisheries management achieve a high degree of integration.
•Conservation of biodiversity is key to ecosystem functioning.
•Redundancy in species’ functionality is essential to prevent
ecosystem ‘collapses’ after extensive human-induced
degradation (Jackson et al., 2001). So, conserving
biodiversity to maximize functional redundancy is a
precautionary EBFM tool.
•Every species is (or can be) important. Ecosystems are
constantly evolving entities, as are the functional roles of
species. We can hardly predict and even infer which species
are or can be keystone in the ecosystem.
•Also, RPs for single-species populations should take due
account of the ecological function they play: biomass must be
kept at levels allowing the species to play its functional role in
the ecosystem.
from Tudela & Short (2005)
FISHERIES MANAGEMENT
EBM
Strategic management
Indicators derived from
ecosystem modeling
Tactical management
EBM indicators
complexity
(“holisticness”)
of indicators
Operational management
Reference levels
Operational framework for
fisheries management
Modified from Christensen (2005)
•Indicators for strategic ecosystem-based management
are expected to inform about the structural and
functional properties of the exploited system
•In contrast, indicators for lower-level, tactical and
operational ecosystem-based management are likely
to refer to basic biological/ecological aspects
They can even be the same as those used in
tactical and operational TROM though used
to define different operational management
frameworks, based on RPs set according to
ecosystem-based criteria.
Example:
Strategic ecosystem-based fisheries management
pressure indicator + pressure indicator = state indicator
(TLfishery)
(%PPR)
(proxy EO)
The two parameters %PPR and TLfishery , taken
together, provide an insight into the intensity of
human exploitation of a given marine ecosystem, as
regards its overall structure and functioning
% PPR
Different exploited
ecosystems/fisheries
can be defined and
characterised by the
value of their % PPR
and TLfishery
exploited
ecosystem 2
exploited
ecosystem 1
TLfishery
The composite indicator %PPR- TLfishery inform on
the situation of the ecosystem with respect of the
‘sustainability’ of the overall exploitation pattern
i.e. 2 different fisheries scenarios
% PPR
exploited
ecosystem 1
TLfishery
exploited
ecosystem 2

Scenario 2 is likely to
be less disrupting than
Scenario 1 in terms to
ecosystem functioning
The composite indicator %PPR- TLfishery inform on
the situation of the ecosystem with respect of the
‘sustainability’ of the overall exploitation pattern
i.e. 2 different fisheries scenarios
% PPR
exploited
ecosystem A
exploited
ecosystem B
TLfishery

Scenario B is likely to
be less disrupting than
Scenario A in terms to
ecosystem functioning
threshold for ecosystem
overfishing
extensive ecosystem
degradation (EO)
% PPR
buffer zone
proposed ‘precautionary’
curve for EBFM-based
reference points
‘healthy’ exploited
ecosystem
TLfishery
EBMSCp:
Latest: L index,
now with TE
(Libralato et al.,
in press)
3,5
3,4
35
3,3
3,2
TLcatch
3,1
25
PPR
3,0
2,9
2,8
15
2,7
2,6
2,5
1975
5
1985
1995
2005
year
2015
2025
1975
100
1985
1995
2005
year
2015
2025
2005
year
2015
2025
0,4
90
80
0,3
70
L index
psust
60
50
40
0,2
30
0,1
20
10
0
1975
0,0
1985
1995
2005
year
2015
2025
1975
1985
1995
Apparently strong catch reductions are needed, but …
… eradicating IUU catches and strongly improving
selectivity (so as to reduce discards) would considerably
move fisheries closer to EMSC values