A Specific Proposal By RAM

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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 Fishes
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Cyclic Advantage Hypothesis

• The next dominant to sardine is anchovy
• Yes! As I predicted
• The second next is chub mackerel
• Many people agree now

Matsuda et al. (1992) Res. Pop. Ecol. 34309-319
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A mathematical model for cyclic advantage
hypothesis

• dx/dt c1r1 (t)2x 4y zxdy/dt c2r2
  (t) x 2y 4zydz/dt c3r3 (t)4x y
  2zz
• When y,z0, x r1/2, at which
• dy/dtgt0 because r2-xgt0
• dz/dtlt0 because r3-4xlt0
• Interior equilibrium is locally unstable

A
A
A
A
C
C
B
B
B
B
C
C
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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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QA

• 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 matured
1970s 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
F during 1970-80s
--Actual
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Probability of stock recoveryKawai et al. in
press

• 1990s is Japans 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
  hypothesis. (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-ment
  action with the recent survey data
• To examine a large variety of parameter values 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(1hxi)
• Policy 2 (switching SF)
• Fi fi xi/(Sxi) (1hxi)
• Fishers may focus on relatively abundant fish
  species.

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Switching increases stabilizes total catch,
save it at low levels
No Switching (F0.5)
Switching
Switching
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Is SBT monotonically recovering? Mori et al.
Pop.Ecol. 2001
Matures (million)
Immatures (10million)
Total (10 million)

Stock size
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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. 43125-13)
• 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
  biological diversity and for using their
  biological resources in a sustainable manner
• These are 2 of the 3 WWF missions