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A Specific Proposal By RAM

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.

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A Specific Proposal By RAM

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  1. 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)

  2. Anchovy Horse mackerels Pacific saury Chub mackerel Sardine Catch in Japan (1000 mt) Species Replacement of Pelagic Fishes

  3. sardine mackrel Anchovy, Pacific saury, jack mackerel 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. 34:309-319

  4. 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 which dy/dt>0 because r2-x>0 dz/dt<0because r3-4x<0 • Interior equilibrium is locally unstable A A A C C A B B B B C C

  5. “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 (positivelyor negatively) correlated;

  6. Q&A • Will western Pacific chub mackerel really recover? • It depends on the fishing pressure

  7. Past recovery of chub mackerel Back to the 1950s

  8. Large fluctuation of recruitment Strong year classes appeared twice

  9. Immatures were caught before matured

  10. Fishers missed chance of recoveryKawai,…,Matsuda, Fish. Sci. in press *F during 1970-80s --Actual

  11. Probability of stock recoveryKawai et al. in press 1990s is Japan’s “lost 10 years”.

  12. 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)

  13. 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 manyuntested assumptions and intuitive understanding is difficult • Indeterminacy (Yodzis 1988): Results (+/-) vary with small change in parameter values

  14. 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.

  15. 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

  16. 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= fixi/(Sxi)(1+hxi) Fishers may focus on relatively abundant fish species.

  17. Switching increases & stabilizes total catch, save it at low levels No Switching (F=0.5) Switching Switching

  18. Is SBT monotonically recovering? Mori et al. Pop.Ecol. 2001 #Matures (million) #Immatures (10million) #Total (10 million) Stock size

  19. Inertia of over-fished age-structure Inverse Baby-boom effect We must publish this before stock stops increasing.

  20. 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

  21. 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

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