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

Question?

Question?

Which fishing gear is the least damaging?

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

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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!

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