1 indicators for fisheries management: a french experience marie-joëlle rochet, verena trenkel,...
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Indicators for fisheries management: a French
experience
Marie-Joëlle Rochet, Verena Trenkel, Jean-Charles Poulard, and Jacques
Bertrand Robert Bellail, Olivier Le Pape, Jean-Claude Mahé, Jocelyne Morin, Ivan Schlaich, Arnauld
Souplet From: ICES Journal of Marine Science, in press
SCMEE Transversal workshop on ecosystem approach to fisheries
Salammbo, 7-9 September 2005
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Outline
Definitions and context A method to combine indicators for
a diagnosis of fishing impacts A French experience: using survey
data to estimate indicators and to inform stakeholders
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What is an indicator?
Something that can be measured and monitored on an appropriate time-scale
Something related to a management objective: “Something we care about”
Something simple and understandable
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Ecosystem approach to fisheries management
Focus on marine ecosystems rather than single stocks– bycatch species– habitats– food webs...
Consider several levels of organisation Consider multiple uses and objectives Impact of fishing on ecosystems vs
consequences of ecosystem state for fisheries
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Why do we need indicators for fisheries management?
Monitor Status Support Decision-Making Inform Dialogue Evaluate Performance of
Management Actions Provide Understanding
Need Reference Points/States/Something!
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Indicators, reference points and decision criteria
Hall & Mainprize, 2004
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Reference direction
Increasing fishing impact
Target RP Limit RP
Indicator I1
Factor AFactor BFactor C
Use expected effect of fishing as a“reference direction” for each indicator
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Reference directions:Several indicators
Increasing fishing impact
Indicator 2
Indicator 1
Indicator 3
Combine changes in indicatorsrelative to expected effect of fishing
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Where you want to go depends on where you start
from Retrospective initial state assessment
determines undesirable directions– light fishing impact
do not increase fishing impact– severe fishing impact
do not stay here do not increase fishing impact
Combine indicator trends to assess if system moved towards these directions
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Combine trends to improve interpretation
tiN,̂
tiL,
More large fishMore large andless small fish
Less small fish
More fish Less fish
More small fishMore small andless large fish
Less large fish
More small and large fish: good recruitment and low mortality (F or M)Shift in spatial distribution: more fish in survey areaMore old fish: mortality decreases (F or M) and slower growthMore small fish and faster growth
FishingEnvironmentFish. x Envir.
Abundance
Ave
rage
leng
th
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Decide which combinations you like
tiN,̂
tiL,
More large fishMore large andless small fish
Less small fish
More fish Less fish
More small fishMore small andless large fish
Less large fish
Not impacted initial state do not increase fishing impact
p=0.9025
p=0.04875
p=0.025 p=0.95 p=0.025
p=0.025
p=0.95
p=0.025
Test results, a=0.05
H0: stationary populations, independent indicators
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Decide which combinations you like
tiN,̂
tiL,
More large fishMore large andless small fish
Less small fish
More fish Less fish
More small fishMore small andless large fish
Less large fish
Impacted initial state do not stay here do not increase fishing impact
p=0.950625
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lfre
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trees
0.024 0.025
p=0.025p=0.95p=0.975
DeterioratingNot deteriorating
0.951
Not impacted initial state
tiN ,ˆ
tiL ,
DeterioratingNot improvingImproving
0.025 .0006
Impacted initial state
0.90 0.0240.024 .0006
tiN ,ˆ
tiN ,ˆ
tiL ,
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More than 2 indicators:community level
0.023
tL
tN̂
tW
0.023 0.048 0.024 0.025
t
0.0230.859
p=0.025p=0.05p=0.95p=0.975
DeterioratingNot deteriorating
tN̂
tB̂
t
6.10-46.10-4
Not impacted initial state do not increase fishing impact
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More than 2 indicators
Impacted initial state do not stay here do not increase fishing impact
tL
tN̂
tB̂ tB̂
tW
t
t
t
tN̂ tN̂ tN̂
DeterioratingNot improvingImproving
tW
t
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French surveys
Vilaine
Seine
Somme
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Survey time-series
Initial purpose: target fish species abundance indices / recruitment indices
Consistent information on– target / non-target species– populations / communities
Use for populations / community monitoring
Comparative approach
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IndicatorsLevel Indicator Definition Expected effect of
fishing
tiN,̂log Log-transformedpopulation abundance forspecies i
PopulationtiL,
Average length ofpopulation i
tiW,Average weight inpopulation i
tB̂ Total biomass
tN̂ Total abundance in thecommunity
tW Average weight
tLAverage length Community
telP ,arg Proportion of large indiv.in community
t Size spectrum slope
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Results: Bay of Biscaypopulation indicators
1990 1995 2000
0.0
0.2
0.4
0.6
LOLIFOR P( Stationnaire )= 0.01081
1990 1995 2000
0.0
0.2
0.4
LOLIVUL
1990 1995 2000
01
23 Anglerfish
LOPHBUD
1990 1995 2000
02
4
LOPHPIS
Ave
rage
wei
ght
Monkfish
Veined squid European squid
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Bay of Biscay 1987 - 2004: slopes in ln(Abundance) = population growth
rates
-0.3
-0.2
-0.1
0.0
0.1
0.2
0.3
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Bay of Biscay 1987-2004: slopes in size
indicators, population level
Average weight
Slo
pes
-0.3
0-0
.25
-0.2
0-0
.15
-0.1
0-0
.05
0.00
0.05
Average length
Slo
pe
s
-2.0
-1.5
-1.0
-0.5
0.0
0.5
1.0
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Results: community indicators
Bay of Biscay
1990 1995 2000
22.5
23.0
23.5
24.0
24.5
Total abundance
ln(A
bond
ance
)
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www.ifremer.fr
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fish
1990 1995 2000
-0.0
50
.05
0.1
5
threshold 20 cm P(stationary)= 0.09
1990 1995 2000
-0.0
20
.02
0.0
60
.10
threshold 23.33 cm P(stationary)= 0.006
1990 1995 2000
-0.0
10
.01
0.0
30
.05
threshold 26.66 cm P(stationary)= 0.001
1990 1995 2000
0.0
00
0.0
10
threshold 29.99 cm P(stationary)= 0.001
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Towards a
diagnostic:
Literature based initial state
assessment
1982-2002
1995-2001
1987-2002
1997-2002
1999-2002
1990-2000
1995-2002
1997-2002
1995-2002
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Results: populationsV ilaine E stuary
tiN ,ˆ
tiL ,
2 6 3
E ast C orsicatiN ,
ˆ
tiL ,
1 19 2
C eltic S eatiN ,
ˆ
tiL ,
1 8 24 1 1 8
B ay of B iscaytiN ,
ˆ
tiL ,
3 17 24 1 3 3
Deteriorating,p=0.0128
Deteriorating,p=0.0002
Not improving
Stationary
11 pop.
43 pop.
22 pop.
51 pop.
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Results: initially not impacted communities
tL
tN̂
tB̂
tW
t
Stationary,p(no
change)=0.859
Vilaine,East Corsica
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www.ifremer.fr
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communities
Celtic Sea
tL
tN̂
tB̂
tW
Deteriorating,p(no change)=0.021
Lions,Somme,Seine,S. North Sea,East. Channel
tL
tN̂
tB̂
tW
t
Not improving,p(no change)=0.815
Bay of Biscay
tL
tN̂
tB̂
tW
t
Not improving,p(no change)=0.021
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Results: summary
System Initial state Populations Community Overall
Seine Impacted
Somme Impacted
Vilaine Unimpacted
East Corsica Unimpacted
Lions Impacted
S. North Sea Impacted
Channel Impacted
Celtic Impacted
Biscay Impacted
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Conclusions /Future developments
Separate indicator estimation from diagnosis: desirable trends management objectives
Importance of initial state assessment: improve methods (in relation to management objectives)
Power and risk can be adjusted through risks of individual tests
More indicators to refine interpretations Develop a taxonomy of expected fishing
impacts
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• Yearly standardized sampling since 1994 • About 1100 stations observed from the Alboran Sea to
the Aegean Sea, including Cyprus since 2005• More than 100 species studied• More than 15 partners in 9 countries
MEDITS SURVEY International bottom trawl survey in the Mediterranean
Since 2002, priority action of the European regulation on fishery data collection in the Mediterranean
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Geographical areas 13 areas based on the GFCM management
units
1
6
7
8
9
1110
16GFCM 15+1
6
17
18
19
20
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