1

Adaptive Management and Adaptive Management and Community Interaction in Community Interaction in

Fisheries Fisheries

• Hiroyuki MATSUDA, (Ocean Research Institute, University of

Tokyo, Japan)

2

Requiem to MSYRequiem to MSY

• Ecosystem is uncertain, non-equilibrium and complex

• MSY ignores all the three.Recovery probability of mackerel

90年代の未成魚乱獲を続けると

70-80年代の漁獲圧なら資源回復確率

Species replacement AM makes chaos.

被食者密度

捕食者密

度

3

What is Adaptive What is Adaptive Management?Management?

=Adaptive Learning & Feedback Control

Data

Dynamics Model

State Variable

Decision Making of Fisheries Management

Fish Stock Dynamics with

Fishery

Toshio Katsukawa: Doctoral dissertation 2002

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The pelagic fishes fluctuate The pelagic fishes fluctuate greatly even without fisheries, greatly even without fisheries,

Cat

ch in

Jap

an (

1000

mt) Anchovy

Horse mackerelsPacific sauryChub mackerelSardine

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Cyclic Advantage HypothesisCyclic Advantage Hypothesis

The next dominant to sardine is anchovy –Yes! As I predicted

The second next is chub mackerelMany experts agree now Anchovy, Pacific sau

ry, jack mackerel

mackrelsardine

Matsuda et al. (1992) Res. Pop. Ecol. 34:309-319

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QQ && A A

Q: Will western Pacific chub mackerel really recover?

A: It depends on the fishing pressure.

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Large fluctuation of recruitmentLarge fluctuation of recruitment

Strong year classes appeared twice

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Immatures were caught before maturedImmatures were caught before matured

1970s 1980s 1990s 1993-%immatures 65.0% 60.

0%87.0%

90.6%

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Fishers missed chance of recoveryFishers missed chance of recoveryKawai et al. (2002: Fish. Sci.68:961-969))

F during 1970-89

Actual

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Probability of stock recoveryProbability of stock recovery

1990s is Japan’s “lost 10 years”.

百万トン資源回復確率

Kawai et al. (2002: Fish. Sci.68:961-969))

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Future of Pelagic Fish Populations Future of Pelagic Fish Populations in the north-western Pacific:in the north-western Pacific:

• If overfishing of immatures continues,– Chub mackerel will not recover forever;

• If cyclic advantage hypothesis is true,– Sardine will not recover forever;

• Do not catch immatures too much– The overfishing is an experiment for my

hypothesis. (Adaptive mismanagement)

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Conclusion #1Conclusion #1

• Pelegic fish has fluctuated without fisheries;

• Collapse of sardine is not due to overfishing; however,

• The impact of fisheries on pelagic fishes when it was at low levels is too high to recover.

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Conclusion #2Conclusion #2

• Over-fishing may cause impact on both a target species and other species.

• Monitor target and other species for fisheries controlling procedures

• Future stock depends on not only impact on a target but also other species & habitats.

• These are hypotheses. We need risk assessment and adaptive management

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Five PrinciplesFive Principles

1. Do not catch decreased fishes;

2. Do not catch immature fishes;

3. Catch temporally dominant fishes;

4. Improve selective fishing;

5. Monitor not only a target species, but its prey, predator, competitor etc.

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Management in prey-predator Management in prey-predator cycles cycles and adaptive evolutionsand adaptive evolutions

(Matsuda & Abrams in review)(Matsuda & Abrams in review)

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Effects of predator-prey Effects of predator-prey interactions on sustainable yield interactions on sustainable yield

Sto

ck &

yie

ld

(1 )1

dN r N Pdt

fNNK hN

Prey abundance

1bfN

hNdP d qE Pdt

17

Sto

ck &

yie

ld

Fishing effort

Y

P

The effort that achieves MSY can be close to the effort at which the stock collaps

es.

Non-Standard relationship betStandard relationship between effort and yieldween effort and yield

Non-Non-Standard relationship Standard relationship between effort and yieldbetween effort and yield

Stock may increase in population size with increasing fishing effort

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(1 )1

dN r N P qENdt

fNNK hN

1bfN

hNdP d Pdt

If the prey is exploited,If the prey is exploited,(Matsuda & Abrams unpubl.)(Matsuda & Abrams unpubl.)

dN/dt=0

dP/dt=0

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If the prey is exploited,If the prey is exploited,

Increasing fishing effort decreases the predator density more than the prey density.

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Cycle increases average yield.Cycle increases average yield.

Stock

Yield

Prey

Predator

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If fishing effort is regulated by If fishing effort is regulated by stock abundance,...stock abundance,...

dE/dt = u(N-N

T)

(1 )1

dN r N P qENdt

fNNK hN

1bfN

hNdP d gP Pdt

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• Feedback control may result in extinction of either fishery or predator.

(a)(b)(c)

(d)(e) (f)Feedback control by a target stock Feedback control by a target stock makes irregular fluctuations.makes irregular fluctuations.

Prey

Predator

Fishing effort