Pelagic IndicatorsPelagic Indicators

EU INCO-DEV EU INCO-DEV Knowledge Base for fisheries management (KNOWFISH)Knowledge Base for fisheries management (KNOWFISH)

Tracey Fairweather & Carl van der LingenTracey Fairweather & Carl van der LingenMarine and Coastal ManagementMarine and Coastal Management

Why do we want indicators?Why do we want indicators? UNCED (1992) & UN CSD (1994) - Indicators:UNCED (1992) & UN CSD (1994) - Indicators:

decision-making in self-regulating system decision-making in self-regulating system convey crucial technical information to non-technical usersconvey crucial technical information to non-technical users framework for evaluating managementframework for evaluating management

SA committed to WSSD goal of implementing EAF:SA committed to WSSD goal of implementing EAF: quantitative ecosystem indicators & define reference pointsquantitative ecosystem indicators & define reference points integrate ecological, environmental, social & economic integrate ecological, environmental, social & economic

perspectivesperspectives

Challenges: Challenges: Selection Selection Reference pointsReference points CommunicatingCommunicating Response timeResponse time

The SA Pelagic Case Study…The SA Pelagic Case Study…

Fishery overviewFishery overview Catches, products, Catches, products,

management…management…

Candidate indicatorsCandidate indicators Selected examplesSelected examples

ConclusionsConclusions Management implications…Management implications…

Fishery OverviewFishery Overview Fish caught using Fish caught using

a purse-seine net.a purse-seine net.

Multi-species Multi-species fisheryfishery

3 dominant species 3 dominant species >95% of landings>95% of landings

Other species:Other species: juvenile Cape juvenile Cape

horse mackerel horse mackerel (maasbanker)(maasbanker)

chub mackerelchub mackerel lantern fishlantern fish light fishlight fish

anchovy

sardine

redeye round herring

Catches & VariabilityCatches & Variability Large volume fishery Large volume fishery

avg. ~ 300 000t p.a.avg. ~ 300 000t p.a. 2004 = 42004 = 4thth consecutive consecutive

yr landings >500 000tyr landings >500 000t

Sardine catches have Sardine catches have steadily increased in the steadily increased in the last decade.last decade.

Fishing predominantly Fishing predominantly inshore off the west and inshore off the west and southwest coasts. southwest coasts.

Small pelagic species are Small pelagic species are subject to inherent, large-subject to inherent, large-scale fluctuations in scale fluctuations in population size.population size.

Anchovy

Sardine

Catch distribution 1987-19980

100

200

300

400

500

600

1949

1952

1955

1958

1961

1964

1967

1970

1973

1976

1979

1982

1985

1988

1991

1994

1997

2000

2003

year

tho

usa

nd

s o

f t

on

s

ANCHOVY

SARDINE

REDEYE

Products & Socio-EconomicsProducts & Socio-Economics Anchovy are reduced to fish oil Anchovy are reduced to fish oil

and meal (70% caught are and meal (70% caught are recruits ~ 6 months). recruits ~ 6 months).

sardine are canned - pet & sardine are canned - pet & human consumption, frozen or human consumption, frozen or used for bait (adult fish).used for bait (adult fish).

Redeye are reduced to fish oil Redeye are reduced to fish oil and meal, some are canned.and meal, some are canned.

Value of the fishery ~ R1 billion Value of the fishery ~ R1 billion in 2003.in 2003.

Fishery employs ~ 8 000 workers Fishery employs ~ 8 000 workers 5 300 full-time 5 300 full-time 2 500 part-time2 500 part-time 700 sea-going700 sea-going 7100 factory workers7100 factory workers

SA’s most transformed fishery.SA’s most transformed fishery.

Research & ManagementResearch & Management Fishery independent surveys Fishery independent surveys

conducted twice a yearconducted twice a year recruitment strength (May)recruitment strength (May) spawner biomass (Nov)spawner biomass (Nov)

Hydro-acoustics used to Hydro-acoustics used to estimate fish biomass. estimate fish biomass.

Multi-species fishery = Multi-species fishery = significant by-catch problems.significant by-catch problems.

By-catch problem 1: juvenile By-catch problem 1: juvenile anchovy & sardine school anchovy & sardine school togethertogether..

By-catch problem 2: adult By-catch problem 2: adult sardine & redeye school sardine & redeye school together.together.

Commercial catches sampled by Commercial catches sampled by inspectors, field station inspectors, field station personnel and observers.personnel and observers.

Candidate IndicatorsCandidate Indicators

Mean length of catch Mean length of catch Total mortality Total mortality Exploitation rateExploitation rate Ratio of by-catchRatio of by-catch Length at 50% maturity Length at 50% maturity Centre of gravity of catchesCentre of gravity of catches

Methods from literature Methods from literature Addressed stakeholder concernsAddressed stakeholder concerns

Length at 50% maturityLength at 50% maturity L50 documented as declining L50 documented as declining

following heavy exploitation and following heavy exploitation and collapse of the collapse of the sardine sardine resource resource and increasing during stock and increasing during stock recovery. recovery.

Such plasticity could be caused by Such plasticity could be caused by a number of factors in a number of factors in combination.combination.

Maturity ogives calculated for 5 Maturity ogives calculated for 5 periods within the time series.periods within the time series.

annual sardine Lannual sardine L5050 & sardine & sardine spawner biomass = highly spawner biomass = highly significant positive correlation significant positive correlation (R(R22=0. 452, p<0.01, n=49).=0. 452, p<0.01, n=49).

-0.2

0.0

0.2

0.4

0.6

0.8

1.0

12 13 14 15 16 17 18 19 20 21 22 23 24 25 26

caudal length (cm)

% m

atu

re f

emal

es

1953-64

1965-75

1976-87

1988-95

1996-04

50%

15

16

17

18

19

20

21

22

1953 1958 1962 1966 1970 1974 1978 1982 1987 1991 1996 2000 2004

year

cau

dal

len

gth

(cm

)

0

1

2

3

4

5

mill

ion

s o

f to

ns

sardine L50

sardine spawner biomass

L50L50 Each moving average data series for Each moving average data series for

sardine sardine provided increasingly better fits:provided increasingly better fits:

3yr R3yr R22=0.575 (0.715 polynomial)=0.575 (0.715 polynomial) 5yr R5yr R22=0.729 (0.818 polynomial)=0.729 (0.818 polynomial) 7yr R7yr R22=0.821 (0.870 polynomial)=0.821 (0.870 polynomial)

Anchovy Anchovy data collected during annual data collected during annual fisheries independent surveys since 1984.fisheries independent surveys since 1984.

Annual anchovy L50 has no correlation Annual anchovy L50 has no correlation (R(R22=0.008) to spawner biomass est. =0.008) to spawner biomass est.

Shorter-lived species = less Shorter-lived species = less maneuverability in age at maturity. maneuverability in age at maturity.

This indicator will be of limited use for This indicator will be of limited use for monitoring anchovy. But suggested monitoring anchovy. But suggested descriptive indicator descriptive indicator for sardine.for sardine.

15

16

17

18

19

20

21

1953 - 59 1961 - 67 1969 - 75 1977 - 83 1985 - 91 1993 - 99

year

cau

da

l len

gth

(cm

)

0.0

0.5

1.0

1.5

2.0

bio

mas

s (x

106

ton

s)

L50 FS 7 biomass 7

15

16

17

18

19

20

21

1953 - 57 1961 - 65 1969 - 73 1977 - 81 1985 - 89 1993 - 97

year

cau

da

l len

gth

(cm

)

0.0

0.5

1.0

1.5

2.0

bio

mas

s (x

106 t

on

s)

L50 FS 5 biomass 5

15

16

17

18

19

20

21

1953 - 55 1962 - 64 1971 - 73 1980 - 82 1989 - 91 1998 - 2000

year

cau

dal

len

gth

(c

m)

0.0

0.5

1.0

1.5

2.0

2.5

bio

mas

s (x

106 t

on

s)

L50 FS 3 biomass 3

3 year

5 year

7 year

15

16

17

18

19

20

21

1953 - 59 1961 - 67 1969 - 75 1977 - 83 1985 - 91 1993 - 99

year

cau

da

l len

gth

(cm

)

0.0

0.5

1.0

1.5

2.0

bio

mas

s (x

106

ton

s)

L50 FS 7 biomass 7

15

16

17

18

19

20

21

1953 - 57 1961 - 65 1969 - 73 1977 - 81 1985 - 89 1993 - 97

year

cau

da

l len

gth

(cm

)

0.0

0.5

1.0

1.5

2.0

bio

mas

s (x

106 t

on

s)

L50 FS 5 biomass 5

15

16

17

18

19

20

21

1953 - 55 1962 - 64 1971 - 73 1980 - 82 1989 - 91 1998 - 2000

year

cau

dal

len

gth

(c

m)

0.0

0.5

1.0

1.5

2.0

2.5

bio

mas

s (x

106 t

on

s)

L50 FS 3 biomass 3

3 year

5 year

7 year

RxBi Proportion of By-catchRxBi Proportion of By-catch estimated separately for each of 3 target fisheries: anchovy, estimated separately for each of 3 target fisheries: anchovy,

sardine & redeye. Rsardine & redeye. RssBBAA & R & RRRBBAA will be discussed. will be discussed.

RRssBBAA = mainly juvenile sardine. = mainly juvenile sardine. NB management issue.NB management issue. RRssBBAA & ratio of sardine SB to & ratio of sardine SB to

anchovy SB = strong correlationanchovy SB = strong correlation RR22=0.791 & p<0.01=0.791 & p<0.01

RRRRBBAA = mainly juvenile redeye. = mainly juvenile redeye. Similar pattern to RSimilar pattern to RSSBBAA

RRRRBBAA & ratio redeye SB to & ratio redeye SB to anchovy SB = strong correlationanchovy SB = strong correlation

RR22=0.682 & p<0.01=0.682 & p<0.01

RRssBBAA & R & RRRBBA A can be used as can be used as descriptive indicatorsdescriptive indicators. .

0%

10%

20%

30%

40%

1987 1989 1991 1993 1995 1997 1999 2001 2003

year

pro

p o

f d

irec

ted

cat

ch

0

1

2

3

4

5

sard

ine

bio

mas

san

cho

vy b

iom

ass

PSBa

Bs/BaSardine by-catch

0%

2%

4%

6%

8%

10%

12%

1987 1989 1991 1993 1995 1997 1999 2001 2003

year

pro

p o

f d

irec

ted

cat

ch

0

2

4

6

8

red

eye

bio

mas

san

cho

vy b

iom

assPRBa

Br/Ba

Redeye by-catch

RxBi – Management ImplicationsRxBi – Management Implications Flowcharts intro in 1998 for catch Flowcharts intro in 1998 for catch

categorization (adult TL>16.5cm). categorization (adult TL>16.5cm). Revised in 2003 (adult TL>14cm).Revised in 2003 (adult TL>14cm).

Given the annual L50 – only Given the annual L50 – only 16% 16% of of sardine directed catchsardine directed catch (R (RSSBBSS) ) should be considered should be considered adultadult..

Given TL cut off – Given TL cut off – 71%71% of of sardine sardine by-catch by-catch (R(RSSBBAA) should be ) should be considered considered adult adult sardine, NOT sardine, NOT juvenile.juvenile.

Given the annual L50 – only Given the annual L50 – only 12%12% of of RRSSBBRR should be considered should be considered adultadult..

These results contradict what is These results contradict what is known about the fishery. known about the fishery.

% of sardine-directed sardine catch which is adult

0%

20%

40%

60%

80%

100%

1999 2000 2001 2002 2003

year & category

%

L50 flowchart

% anchovy-directed sardine by-catch which is adult

0%

20%

40%

60%

80%

100%

1999 2000 2001 2002 2003

area & category

%

L50 flowchart

% redeye-directed sardine by-catch which is adult

0%

20%

40%

60%

80%

100%

1999 2000 2001 2002 2003

area & category

%

L50 flowchart

Exploitation rate = F/ZExploitation rate = F/Z

Sardine Sardine Z calculated using Z calculated using von Bertalanffy parameters.von Bertalanffy parameters.

Sardine E < 0.4Sardine E < 0.4 Sardine E not correlated to Sardine E not correlated to

biomass.biomass. But sardine biomass has But sardine biomass has

increased steadily since 1984.increased steadily since 1984. Conclude: sardine Conclude: sardine

management successful.management successful.

Target reference point E*=0.4Target reference point E*=0.4 F=C/N & is assumed to include discards.F=C/N & is assumed to include discards.

Anchovy Anchovy Z derived from Z derived from ecosystem model.ecosystem model.

Anchovy E <0.4 Anchovy E <0.4 Anchovy E weakly correlated Anchovy E weakly correlated

to biomass to biomass Anchovy biomass has also Anchovy biomass has also

increased since 1984.increased since 1984. E = effective performance E = effective performance

indicator for both species.indicator for both species.

0.0

0.1

0.2

0.3

0.4

0.5

1984 1986 1988 1990 1992 1994 1996 1998 2000 2002

year

ex

plo

ita

tio

n r

ate

Fa/Ze

E*

0.0

0.4

0.8

1.2

1984 1988 1992 1996 2000 2004

year

exp

loit

atio

n r

ate Es Kerstan E*

Centre of gravityCentre of gravity To determine changes in the geographical location of catches To determine changes in the geographical location of catches

between years.between years.

Centre of gravity = centroid + axes showing extent of CV.Centre of gravity = centroid + axes showing extent of CV.

A centroid is the weighted mean location (longitude ; latitude) of A centroid is the weighted mean location (longitude ; latitude) of catches for a year.catches for a year.

Centroids of commercial catches of anchovy, sardine by-catch and Centroids of commercial catches of anchovy, sardine by-catch and directed sardine were calculated. directed sardine were calculated.

The majority of catches are taken close inshore between Saldanha The majority of catches are taken close inshore between Saldanha Bay and Gans Bay.Bay and Gans Bay.

The coastline and commercial catch position information was The coastline and commercial catch position information was linearised to aid interpretation of this indicator.linearised to aid interpretation of this indicator.

ECO-UP

1 – 100 100 – 200 200 – 300 300 – 400 400 – 600

Anchovy Catch (tons x 103)

Hout Bay

Cape Point Gans BayCape Agulhas

1993

1995 & 98

1990

1987

20022003

20001992

1999

19881991

1996

19972004

1989

1994

1 – 10 10 – 20 20 – 30 30 – 40 40 – 60

Sardine By-Catch (tons x 103)1995

19872003

2001

19981990

2004

1989

1994

1996

1991 1992 1993

1988

2000

19971999

1 – 100 100 – 200 200 – 300 300 – 400 400 – 600

Sardine Catch (tons x 103)

St Helena Bay

Cape Columbine

Saldanha Bay

19901987

1988

1989

1997 2003 20042002

1992

2001

1991

1999 20001998

1995 1996 1993 1994

1 – 100 100 – 200 200 – 300 300 – 400 400 – 600

Anchovy Catch (tons x 103)

Hout Bay

Cape Point Gans BayCape Agulhas

1993

1995 & 98

1990

1987

20022003

20001992

1999

19881991

1996

19972004

1989

1994

1 – 100 100 – 200 200 – 300 300 – 400 400 – 600

Anchovy Catch (tons x 103)

Hout Bay

Cape Point Gans BayCape Agulhas

1993

1995 & 98

1990

1987

20022003

20001992

1999

19881991

1996

19972004

1989

1994

1 – 10 10 – 20 20 – 30 30 – 40 40 – 60

Sardine By-Catch (tons x 103)

1 – 10 10 – 20 20 – 30 30 – 40 40 – 60

Sardine By-Catch (tons x 103)1995

19872003

2001

19981990

2004

1989

1994

1996

1991 1992 1993

1988

2000

19971999

1 – 100 100 – 200 200 – 300 300 – 400 400 – 600

Sardine Catch (tons x 103)

St Helena Bay

Cape Columbine

Saldanha Bay

19901987

1988

1989

1997 2003 20042002

1992

2001

1991

1999 20001998

1995 1996 1993 1994

1 – 100 100 – 200 200 – 300 300 – 400 400 – 600

Sardine Catch (tons x 103)

1 – 100 100 – 200 200 – 300 300 – 400 400 – 600

Sardine Catch (tons x 103)

St Helena Bay

Cape Columbine

Saldanha Bay

19901987

1988

1989

1997 2003 20042002

1992

2001

1991

1999 20001998

1995 1996 1993 1994Ann

ual C

atch

Ann

ual C

atch

ECO-UP

Conclusions…Conclusions…Indicator & what Indicator & what it measuresit measures

Ecosystem -Ecosystem -Biological InfoBiological Info

Stakeholder Stakeholder ConcernConcern

Potential Potential UsefulnessUsefulness

L50L50 – how big – how big sardine are when sardine are when they maturethey mature

Large biomass = Large biomass = large L50large L50

Indicates stock Indicates stock collapsecollapse

Descriptive Descriptive IndicatorIndicator

PSBPSBAA – –

proportion juv. proportion juv. sardine in sardine in anchovy catchanchovy catch

Relative recruitment Relative recruitment of the two speciesof the two species

Catch juv = negative Catch juv = negative impact on adultsimpact on adults

Flexibility to deal Flexibility to deal with fluctuationswith fluctuations

Max 20% trade-off Max 20% trade-off (sliding sigmoid (sliding sigmoid curve) included in curve) included in OMP-04OMP-04

Z Z && E E – prop of – prop of fish dying & how fish dying & how heavily fishedheavily fished

Fishing at a low Fishing at a low exploitation rate. exploitation rate. Mgmt has been Mgmt has been conservative to conservative to rebuild stocks. rebuild stocks. Impact of F ltd.Impact of F ltd.

Impact of F is critical Impact of F is critical @ low biomass@ low biomass

Conclusions…Conclusions…Indicator & what Indicator & what it measuresit measures

Ecosystem -Ecosystem -Biological InfoBiological Info

Stakeholder Stakeholder ConcernConcern

Potential Potential UsefulnessUsefulness

LbarLbar – mean – mean length of catchlength of catch

Monitor fisheryMonitor fishery Change is size = Change is size = problem problem

Market implicationsMarket implications

NB Lbar + L50NB Lbar + L50

Need to manage Need to manage by-catchby-catch

Centroids – mean Centroids – mean location of location of catchescatches

Extended range = Extended range = high biomass high biomass Expansion or Expansion or contraction of fish contraction of fish distribution = fisherydistribution = fishery

What does change What does change in distribution mean?in distribution mean?

Has implications…Has implications…

Population Population structure = key structure = key issue – need to issue – need to monitor TAB monitor TAB

Few indicators were applicable to anchovy for two main reasons: the logistics of data collection and the implications of being a short-lived particularly small pelagic fish.

Can we incorporate KNOWFISH Can we incorporate KNOWFISH indicators into management ?indicators into management ?

Determine appropriate suite of indicators for management using refined Determine appropriate suite of indicators for management using refined selection criteria from a rigorous scoring procedure, e.g.:selection criteria from a rigorous scoring procedure, e.g.:

Rochet and Rice 2005: Rochet and Rice 2005: concreteness, theoretical basis, public concreteness, theoretical basis, public awareness, cost, measurement, availability of historic data, awareness, cost, measurement, availability of historic data, sensitivity, responsiveness, specificity.sensitivity, responsiveness, specificity.

Degnbol & Jarre 2004:Degnbol & Jarre 2004: acceptability among stakeholders, acceptability among stakeholders, observability, relation to fisheries management (traffic light approach).observability, relation to fisheries management (traffic light approach).

Assess if indicators are redundant, consider cost and ease of translation Assess if indicators are redundant, consider cost and ease of translation into practical management measures.into practical management measures.

Where possible, these indicators will be incorporated into Pelagic Where possible, these indicators will be incorporated into Pelagic fisheries management in the coming year.fisheries management in the coming year.

Thank youThank you