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SENSITIVITY ASSESSMENT
A TOOL FOR SPATIO-TEMPORAL MANAGEMENT
OF FISHING TECHNIQUES
29 September 2011
World Conference on Marine Biodiversity
Jochen Depestele
Wouter Courtens, Steven Degraer, Jan Haelters, Kris Hostens, Hans Polet,
Marijn Rabaut, Eric Stienen, Sofie Vandendriessche, Magda Vincx
Institute for Agricultural and Fisheries Research www.ilvo.vlaanderen.be/wako
Objective: Develop a tool !
1. No black or white pill can cure
nuances anticipated
Include spatial and temporal aspects
2. No longer see the wood for the trees
few data, but many effects
How to deal with this?
Tool = SENSITIVITY ASSESSMENT !
What?
Existing applications? Range of … ecosystem components
activities
terminologies
But also: APROACHES !
RECOVERABILITY
INT
OL
ER
AN
CE
SENSITIVITY
Roadmap
SCOPING
SPEC. SENSITIVITY ASSESSMENT
SENSITIVITY MAPS
SELECTION OF UNIT OF ANALYSIS un
ce
rtain
ty
Roadmap
un
ce
rtain
ty
SCOPING
SPEC. SENSITIVITY ASSESSMENT
SENSITIVITY MAPS
Assumptions & limitations
1 fishing „event‟
no reference condition
Which marine feature? How?
(1) species within
(2) adult specimen
(3) which species?
SELECTION OF UNIT OF ANALYSIS
Roadmap
un
certa
inty
SCOPING
SPEC. SENSITIVITY ASSESSMENT
SENSITIVITY MAPS
SELECTION OF UNIT OF ANALYSIS
SPECIES FISHING
TRAITS
PRESSURES SPECIES
SENSITIVITY
INDEX
recoverability assessment
intolerance assessment
Intolerance: pressure selection
Be comprehensive: Rio de Janeiro Declaration (1992):
“lack of full scientific certainty shall not be used as a reason for postponing cost-effective measures to
prevent environmental degradation”
Pressure categories: DBP, IBP, IPP, ICP
Pressures: within ecosystem components
for both fishing gears
With or without stakeholders
Intolerance: scoring principle
Objective = discriminate species and gears
“+3” “-3” (neg intolerance = pos effect)
Scoring mechanisms
1. Quantitative data
2. Traits-based scoring
3. No information
Mortalities Beam trawl Trammel net
catch
tow path
ghost fishing
others
X
X
/
N.N.
X
/
X
N.N.
Intolerance: scoring example
DBP = “extraction of epibenthic spp.”
No information:
Highlight lack of data
or
Delphi-technique for scoring
Intolerance: scoring example
DBP = “extraction of epibenthic spp.”
Mortalities Beam trawl Trammel net
catch
tow path
ghost fishing
others
X
X
/
N.N.
X
/
X
N.N.
Quantitative data available:
- standardize by fishing effort or landings
- divide in 4 equal parts for scoring
Intolerance: scoring example
DBP = “extraction of epibenthic spp.”
Mortalities Beam trawl Trammel net
catch
tow path
ghost fishing
others
X
X
/
N.N.
X
/
X
N.N.
Traits-based approach (modified ERAEF)
- encounterability
- selectivity
- post-capture mortality
Intolerance: scoring example
DBP = “extraction of epibenthic spp.”
Mortalities catch tow path ghost Weighed
sum Factor 0.1 0.9 0.1*0.15
Beam Trawl
Asterias rubens
Liocarcinus holsatus
Ophiura ophiura
2
3
2
1
2
3
0
0
0
1.1
2.1
2.9
Trammel Net
Asterias rubens
Liocarcinus holsatus
Ophiura ophiura
2
3
0
0
0
0
0
2
0
0.2
0.33
0
Intolerance: scoring example
DBP = “extraction of epibenthic spp.”
Mortalities catch tow path ghost Weighed
sum Factor 0.1 0.9 0.1*0.15
Beam Trawl
Asterias rubens
Liocarcinus holsatus
Ophiura ophiura
2
3
2
1
2
3
0
0
0
1.1
2.1
2.9
Trammel Net
Asterias rubens
Liocarcinus holsatus
Ophiura ophiura
2
3
0
0
0
0
0
2
0
0.2
0.33
0
Intolerance score
Towards one intolerance score?
Worst case scenario/score (ie. lethal)
Weighing based on expert judgement lethal scores can be worse than others?
Adding up all pressures but aggregated in well thought categories
Pressures per category without adding up
Scoring ~ N(pressures)
Recoverability
= ability to return to a state before disturbance
bio-geographical population size
opportunistic equilibrium (Life history traits: clutch size, growth rate…)
Sensitivity
= f(intolerance, recoverabilty)
Single ranking of species over gears
Expert-based
matrix
(a)symmetric
Recoverability
NoneVery low
(>25 yr.)
Low
(>10–25 yr.)
Moderate
(>5 -10 yr.)
High (1 -
5 yr.)
Very high
(<1 yr.)
Immediat
e (< 1 week)
Intolerance
High Very high Very high High Moderate Moderate Low Very low
Intermediate Very high High High Moderate Low Low Very Low
Low High Moderate Moderate Low Low Very Low NS
Tolerant NS NS NS NS NS NS NS
Tolerant* NS* NS* NS* NS* NS* NS* NS*
Not relevant NR NR NR NR NR NR NR
© M
arL
IN
Sensitivity
= f(intolerance, recoverabilty)
Single ranking of species over gears
Algorithm-based
intol * recov
Euclidean distance
)(int/1 receSI
© Smith et al. (2007)
Sensitivity maps
Gear * time period X
S
S
S
Ecosystem
component Species X
Stelzenmüller et al. (2010):
Spatial scale
~ bio-geographical population
of ecosystem component
1max
*
allspecies
speciesspecies
speciesSI
SIPOS
Sensitivity maps
Gear * time period X
Stelzenmüller et al. (2010):
Spatial scale
~ bio-geographical population
of ecosystem component
1max
*
allspecies
speciesspecies
speciesSI
SIPOS
© INBO
beam trawl in winter
S f(DBP, density)
Sensitivity maps
Gear * time period X
Stelzenmüller et al. (2010):
Spatial scale
~ bio-geographical population
of ecosystem component
1max
*
allspecies
speciesspecies
speciesSI
SIPOS
trammel net in winter
S f(DBP, density)
© INBO
Sensitivity maps
Gear * time period X
Stelzenmüller et al. (2010):
Spatial scale
~ bio-geographical population
of ecosystem component
1max
*
allspecies
speciesspecies
speciesSI
SIPOS
trammel net in summer
S f(DBP, density)
© INBO
Roadmap
SCOPING
SPEC. SENSITIVITY ASSESSMENT
SENSITIVITY MAPS
SELECTION OF UNIT OF ANALYSIS
un
ce
rtain
ty
Pedigree criteria low high
Proxy of pressure-species
Understanding of activity-pressure
Empirical basis
Methodological rigour
Validation
Uncertainty
To avoid that what is not known, remains
not known
explicit referral to missing data
Pedigree index
Pedigree criteria low high
Proxy of pressure-species
Understanding of activity-pressure
Empirical basis
Methodological rigour
Validation
Uncertainty
To avoid that what is not known, remains
not known
explicit referral to missing data
Pedigree index
good fit for measure
e.g. discard survival from
tank experiments
Preliminary theory
e.g. vessel disturbance
Uncertainty
To avoid that what is not known, remains
not known
explicit referral to missing data
Pedigree index
good fit for measure
e.g. discard survival from
tank experiments
Preliminary theory
e.g. vessel disturbance
Local, in situ data
Pedigree criteria low high
Proxy of pressure-species
Understanding of activity-pressure
Empirical basis
Methodological rigour
Validation
Replicated?
e.g. 3 peer-reviewed papers
Acceptable method,
limited consensus on
reliability
e.g. discard estimation
from LFD-selectivity
Lessons learnt
I’m starting to see the wood for the trees!
Comprehensive approach
Spatially and temporally explicit
Qualitative information
=/=
no assessment
Thank you for your attention
Contact: Jochen.Depestele@ilvo.vlaanderen.be
Website: www.ilvo.vlaanderen.be/wako
Financially supported by
Institute for Agricultural and Fisheries Research www.ilvo.vlaanderen.be/wako
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