Post on 29-Jan-2016
transcript
2002/6/21 1
SWATT: Statistical Wizards Advisory & Training Team
2002/6/21 2
Specific Proposals
2002/6/21 3
A Specific Proposal By RAM
• Meta-analysis of species interactions and environmental and fishing change (link with H-MAP)
• Prediction of population and community trajectories based result of upon above project.– My comment: to clarify condition to require
each complex model (make it simple as much as I can)
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Species Replacement of Pelagic FishesC
atch
in J
apan
(10
00 m
t) AnchovyHorse mackerelsPacific sauryChub mackerelSardine
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Cyclic Advantage Hypothesis
The next dominant to sardine is anchovy –Yes! As I predicted
The second next is chub mackerelMany people agree
now
Anchovy, Pacific saury, jack mackerel
mackrelsardine
Matsuda et al. (1992) Res. Pop. Ecol. 34:309-319
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A mathematical model for cyclic advantage hypothesis
• dx/dt = c1+[r1 (t)–2x – 4y – z]xdy/dt = c2+[r2 (t)– x – 2y – 4z]ydz/dt = c3+[r3 (t)–4x – y – 2z]z
• When y,z~0, x= r1/2, at whichdy/dt>0 because r2-x>0
dz/dt<0 because r3-4x<0
• Interior equilibrium is locally unstable
A A
AA
BB
BBCC
CC CC
CC
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“Community (multispecies) model is needed when either…
• Species interactions (prey-predator, …) probably affect stock dynamics and coexistence…, and like to understand why or to make a multispecies conservation or management plan.
• Trajectories of species are mutually (positively or negatively) correlated;
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Q&A
• Will western Pacific chub mackerel really recover?
• It depends on the fishing pressure
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Past recovery of chub mackerel
Back to the 1950s
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Large fluctuation of recruitment
Strong year classes appeared twice
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Immatures were caught before matured1970s 1980s 1990s 1993-
%immatures 65.0% 60.0% 87.0% 90.6%
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Fishers missed chance of recoveryKawai,…,Matsuda, Fish. Sci. in press
--Actual
F during 1970-80s
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Probability of stock recoveryKawai et al. in press
1990s is Japan’s “lost 10 years”.
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Future of Pelagic Fish Populations in the north-western Pacific:
• If overfishing of immatures continues,– Chub mackerel will not recover forever;
• If cyclic replacement hypothesis is true,– Sardine will not recover forever;
• Do not catch immatures too much– The overfishing is an experiment for my hypot
hesis. (Adaptive mismanagement)
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Difficulties & hopelessness in ecosystem modeling
• Indirect effects via the third species or adaptive change in traits is often counterintuitive and not negligible in the long-term effect (see Abrams, Polis…);
• We need many untested assumptions and intuitive understanding is difficult
• Indeterminacy (Yodzis 1988): Results (+/-) vary with small change in parameter values
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Adaptive Management, or “Learning by Doing”
• If we change the management action (and already determine how to change it) with recent survey, the risk of mismanagement is much smaller;
• We try several actions in order to understand the ecosystem more detail;
• To learn the history of overfishing.
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Guideline of ecosystem management
• To list up what data we continuously survey;• To determine adaptive change in manage-me
nt action with the recent survey data;• To examine a large variety of parameter valu
es in the ecosystem model and to confirm robustness of the above adaptive management;
• To make falsifiable predictions
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Target switching of multispecies fisheries (Katsukawa & Matsuda, Fish.Res. In press)
Policy 1 (no switching; NSF)Fi= fi /2(1+hxi)
Policy 2 (switching; SF)Fi= fi xi/(xi) (1+hxi)
Fishers may focus on relatively abundant fish species.
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Switching increases & stabilizes total catch, save it at low levels
0
0.1
0.2
0.3
0.4
0.5
900 910 920 930 940 950 960 970 980 990
Time
Cat
ch
Switching
No Switching (F=0.5)
0
0.1
0.2
0.3
0.4
0.5
900 910 920 930 940 950 960 970 980 990
Time
Cat
ch
Switching
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Is SBT monotonically recovering? Mori et al. Pop.Ecol. 2001
Sto
ck s
ize
#Matures (million)#Immatures (10million)#Total (10 million)
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Inertia of over-fished age-structure
Inverse Baby-boom effect
We must publish this before stock stops increasing.
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Age (Size) structured model is needed when…
• Fluctuation in Recruitment is large (Tuljapurkar 1988)
• Fishing pressure is dramatically changed (Mori, Katsukawa, Matsuda 2001 Pop.Ecol. 43:125-13)
• The age at first capture is changed
• The age at maturity is changed
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One of our Goals
• Research to contribute on Biodirvesity Conservation and Sustainable Use
• As by Convention on Biological Diversity– States are responsible for conserving their biolo
gical diversity and for using their biological resources in a sustainable manner
• These are 2 of the 3 WWF missions