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)

2002/6/21 4

Species Replacement of Pelagic FishesC

atch

in J

apan

(10

00 m

t) AnchovyHorse mackerelsPacific sauryChub mackerelSardine

2002/6/21 5

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

2002/6/21 6

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

2002/6/21 7

“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;

2002/6/21 8

Q&A

• Will western Pacific chub mackerel really recover?

• It depends on the fishing pressure

2002/6/21 9

Past recovery of chub mackerel

Back to the 1950s

2002/6/21 10

Large fluctuation of recruitment

Strong year classes appeared twice

2002/6/21 11

Immatures were caught before matured1970s 1980s 1990s 1993-

%immatures 65.0% 60.0% 87.0% 90.6%

2002/6/21 12

Fishers missed chance of recoveryKawai,…,Matsuda, Fish. Sci. in press

--Actual

F during 1970-80s

2002/6/21 13

Probability of stock recoveryKawai et al. in press

1990s is Japan’s “lost 10 years”.

2002/6/21 14

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)

2002/6/21 15

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

2002/6/21 16

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.

2002/6/21 17

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

2002/6/21 18

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.

2002/6/21 19

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

2002/6/21 20

Is SBT monotonically recovering? Mori et al. Pop.Ecol. 2001

　

Sto

ck s

ize

#Matures (million)#Immatures (10million)#Total (10 million)

2002/6/21 21

Inertia of over-fished age-structure

Inverse Baby-boom effect

We must publish this before stock stops increasing.

2002/6/21 22

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

2002/6/21 23

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