A unit of Lasting Forests
Sustained forests; sustained profits
evolving since March 30, 1999

of an Alternative Wildlife Resource Management

Allocating Hunting Effort

Given that a desired total harvest, D, is computed by several techniques for an area, how can it be taken? Harvest effort can be allocated by the manager. This can be by:

1. Hunting days
2. Hunting hours
3. Opening and closing time
4. Probable person-days (or hours) of hunting
5. Permits
6. Prior performance or success (life limits or delays)
7. Clothing and required equipment
8. Weapon type (differential vulnerability)
9. Ammunition type

I - To estimate the number of permits (P) to be issued (and allocating other harvest effort is similar) estimate the proportion of hunting success (S) (e.g., check stations, questionnaires, spy blinds). Suppose the success rate, S, is 0.25.

P = D/S
D = 2500
S = 0.25
P = 2500/0.25
P = 10,000

*Opportunity exists for future research on the implications of this expression. Is it linear? Perhaps it should be proportional to the total population.

II - You want to take 2500 animals from the population. You would like all of them to be legal takes and consumed, but you know there will be cripples, etc. These are animals removed (but they may not ever show up at a check station or reported by hunters. Where you want to take D and you estimate the crippling loss, C, to be a percentage or 0.35 of the reported harvest* then, since

P = D/S

and each successful hunter causes extra mortality of C amount due to crippling loss, then permits are issued to harvest each (1.0 + C) animal.

P = D/S (1.0 + C)

For example, where D = 2500
S = 0.25
C = 0.35
P = 2500/(0.25(l.0 + 0.35))
P = 7,407

III - I want to harvest D = 2000 animals (plus or minus 5%)

Therefore I want to harvest equal to or more than 1900 and equal to of less than 2100.

D = Desired kill (total kill)
S = reported hunter success (21% plus or minus 5%)
0.21 (0.1995 to 0.2205)
C = crippling loss 30% plus or minus 10%
0.30 (0.270 to 0.315)

K = Poaching loss 40% plus or minus 20% (If expressed as % of reported harvest)
0.40 (0.32 to 0.48)
P = Permits to be issued

P = D/(S + CS + KS)

P = D/[S(l + C + K)]

Conditions for issuing the fewest permits:

P = 1900 / (0.2205 + (0.2205)(0.315) + (.48)(.2205) = 1900 /0.3955 = 4,804

Average conditions:

P = 2000/(.21 + (.30)(.21) + (.40)(.21) = 2000/ 0.357 = 5,602

Conditions for issuing maximum number of permits:

P = 2100/(0.1995 + (0.270)(0.1995) + (0.320)(0.1995) = 2100/0.3175 = 6,614

Assume normal distribution and use 1/3 and 2/3 probability levels.

If data are skewed, left and/or right (e.g., the probability of crippling loss being more often less than the number shown than greater than the number) then simulation may be used to show the distribution.

If conventional limits are used (i.e., plus or minus 5% means the data within 1 standard deviation on both sides of the mean), then the feasible zone is where the manager will be correct about 1/3 of the time.

Permits are not always picked up by hunters; political and other pressures may require more be issued than apparently appropriate.

Robert H. Giles, Jr.

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Last revision July 10, 2001.