Adaptive Management and Community Interaction in Fisheries
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Transcript of Adaptive Management and Community Interaction in Fisheries
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Adaptive Management and Adaptive Management and Community Interaction in Community Interaction in
Fisheries Fisheries
• Hiroyuki MATSUDA, (Ocean Research Institute, University of
Tokyo, Japan)
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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
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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
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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