10/8/05 1

An adaptive management for sika deer based on sex-specific hunting

H. Uno, T Fujimoto, T. Saitoh, K. Kaji, T. Kurumada,H. Uno, T Fujimoto, T. Saitoh, K. Kaji, T. Kurumada,

H. Hirakawa, H. Matsuda, K. Tamada,H. Hirakawa, H. Matsuda, K. Tamada,

http://risk.kan.ynu.ac.jp/matsuda/2005/050801IMC.html

10/8/05 2

History of over-harvesting and hunting-ban

Year (source: Hokkaido Prefecture)

10

100

1,000

10,000

100,000

1,000,000

1875 1895 1915 1935 1955 1975 1994

Catch

Heavy winter

Extinction of wolves

10/8/05 3

Purposes of deer management in eastern Hokkaido (1997)

To use deer as natural resources, To avoid extinction and overabundance

of deer, To conserve ecosystems, To decrease damage on agriculture and

forestry

10/8/05 4

Deer Management Program in eastern Hokkaido (1997)

Feedback control for non-equilibrial population

Risk management incorporating heavy snow years (process errors) and measurement uncertainties into account.

Public involvement by disclosure and discussion in mailing list.

10/8/05 5

Stage-Structured Model

)(

)(

)(

)(0)(

0)()(

0)()(0

)1(

)1(

)1(

tN

tN

tN

tLtL

tLtL

tLtr

tN

tN

tN

m

f

c

mmmc

fffc

ff

m

f

c

Lfc(t)= Lmc(t)= exp[-Q(t)Hc(t)]exp[-Mc(t)]exp[-Rc(t+1)],

Lff(t) = exp[-Q(t)Hf(t)]exp[-Mf(t)]exp[-Rf(t+1)] ,

Lmm(t) = exp[-Q(t)Hm(t)]exp[-Mm(t)]exp[-Rm(t+1)] ,

10/8/05 6

Assuming uncertainties

Survival rate of juveniles Lfc: 46% ～ 54%

Survival rate of female adults Lff: 90% ～ 99%

rLff ＝ λ(λ- Lff)/ Lfc

Temporal fluctuation <10% Measurement error of population index <20%

I use parameter sets only when the rate of natural population increase λ : during 15-20% per year (“filtering method” instead of sensitivity analysis)

10/8/05 7

Population IndicesCatch & site per unit effort (per hunter

per day)Spotlight censusAerial (helicopter) censusTraffic accident of JR trains (and cars)Damage on agriculture and forestry

I don’t know the absolute population.

10/8/05 8

Sex-specific hunting

Width of catch fluctuation

> Width of population fluctuation

Catch females to decrease, and catch males to increase.

Sex-specific hunting stabilizes annual catch

We must monitor sex-ratio (1:2 - 1:10)

10/8/05 9

Risk management based on a population dynamic model

0%

2%

4%

6%

8%

10%

12%

2007 2022 2037 2052 2067 2082 2097

Year

Rep

rodu

ctiv

e P

oten

tial

0

1000

2000

3000

4000

5000

6000

7000

Yie

ld

(c) error in life history parameters

0%

1%

2%

3%

4%

5%

6%

7%

8%

9%

2007 2022 2037 2052 2067 2082 2097

Year

Rep

rodu

ctiv

e Po

tent

ial

02004006008001000

12001400160018002000

Yie

ld

(a) No process nor measurement errors (b) Process errors (heavy snows)

0%

10%

20%

30%

40%

50%

60%

2007 2022 2037 2052 2067 2082 2097

Year

Rep

rodu

ctiv

e Po

tent

ial

0

2000

4000

6000

8000

10000

12000

14000

Yie

ld

(d) Accept 10-fold fluctuation

10/8/05 10

Density-dependent hunting pressure　 http://www.hokkaido-ies.go.jp/HIESintro/Natural/ShizenHP2/SIKA/DTdeerHP.htm

%P>50%P1993 Emergency culling

25% < %PGradual population

reductions (catch females)

5% < %PGradual population increases (catch males)

%P <5% or after the severe winter

Hunting bans

10/8/05 11

Trends in Population indicesP

opul

atio

n in

dice

s in

100

3=10

0%

year1990 1995 2000 2003

10/8/05 12

Summary We consider a management policy for a sika deer (Cer

vus nippon) population in the eastern Hokkaido. To make a robust program based on uncertain informat

ion about the deer population, we consider 4 levels of hunting pressures.

The hunting pressure for females is set to increase with the population size.

The simulation results suggest that management based on sex-specific hunting is effective to diminish annual variation in hunting yield.

10/8/05 13

10/8/05 14

Possible factors of deer over-abundance

Success in deer hunting-ban Forest cutting and spread grassland Winter warming Extinction of wolves （ ca.1890）

10/8/05 15

Spatial distribution of sika deer during 1925-1997

Source: Hokkaido Prefecture

AkanTaisetsu

Hidaka