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 2005SCMEE 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 management approach for fisheries is needed

•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)

Strategic management

Tactical management

Operational management

Modified from Christensen (2005)

FISHERIES MANAGEMENT

EBM indicators

Indicators derived from ecosystem modeling

Reference levels

Operational framework for fisheries management

complexity (“holisticness”)of indicators

EBM

•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

TLfishery

exploited ecosystem 2

exploited ecosystem 1

Different exploited ecosystems/fisheries can be defined and characterised by the value of their % PPR and TLfishery

The composite indicator %PPR- TLfishery inform on

the situation of the ecosystem with respect of the ‘sustainability’ of the overall exploitation pattern

% PPR

TLfishery

exploited ecosystem 2

exploited ecosystem 1

i.e. 2 different fisheries scenarios

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

% PPR

TLfishery

exploited ecosystem B

exploited ecosystem A

i.e. 2 different fisheries scenarios

Scenario B is likely to be less disrupting than Scenario A in terms to ecosystem functioning

% PPR

TLfishery

threshold for ecosystemoverfishing

proposed ‘precautionary’curve for EBFM-based reference pointsbuffer zone

‘healthy’ exploited ecosystem

extensive ecosystemdegradation (EO)

EBMSCp:

Latest: L index, now with TE

(Libralato et al., in press)

2,5

2,6

2,7

2,8

2,9

3,0

3,1

3,2

3,3

3,4

3,5

1975 1985 1995 2005 2015 2025

year

TL

ca

tch

5

15

25

35

1975 1985 1995 2005 2015 2025year

PP

R

0

10

20

30

40

50

60

70

80

90

100

1975 1985 1995 2005 2015 2025year

psu

st

0,0

0,1

0,2

0,3

0,4

1975 1985 1995 2005 2015 2025year

L in

de

x

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