1. Harvest Harvested v. unharvested populations –Why are some species not harvested? –Why are some species harvested at different rates? –Why does harvest not seem to affect some species?

2. Harvestable surplus (Leopold 1933) –Originally only the “doomed” surplus Harvest

3. Assuming a surplus –Overharvest Extinction –Regulated hunting has never led to an extinction! –Underharvest Environmental degradation (Think like a mountain!) Loss of recreational opportunities (value!) Harvest

4. Characteristics of harvested populations –Population size –Population stability –Fecundity –Life span –Mortality from other causes Unknown effects –Trophy’s smaller? –Genetics? Harvest

5. Principles –Yield* –Diminishing returns –Compensatory harvest mortality –So which one happens? History, Trial & Error, and Human Dimensions

6. Harvest When populations are limited by some resource (density-dependence/logistic growth; from Caughley & Sinclair 1994 ) –A population is harvested at its growth rate –A population must be stimulated to produce a yield –Harvesting trades off yield against population size

7. Harvest Sustained yield, harvest rate, & population size N Time Accelerating Phase K Inflection Point (½ K) Decelerating Phase N dN/dt Inflection Point (½ K) K

8. Harvest Yield 200 100 0 Population Size 01000750500250 Sustained yield, harvest rate, & population size N dN/dt Inflection Point (½ K) K Harvest 50 150 100 200 0 Surplus or Yield MSY potentially sustainable harvestno harvest sustainable

9. Harvest Yield 200 100 0 Population Size 01000750500250 MSY Lower SYUpper SY Harvestable surplus –Sustained yield (SY) –Maximum sustained yield (MSY) –Optimal sustained yield (OSY)

10. Harvest Population Size + Recruits (Yield) 750 450 300 150 0 Population Size 01000750500250 600 900 1050 1200 75 100 75 Yield MSY Lower SY Upper SY

11. Harvest When populations are not limited by resources (exponential growth)? N Time N dN/dt Yield 200 150 100 50 0 Population Size 01000750500250 Harvest 200 150 100 50 0

12. Harvest Do we need strict regulations or is the harvest self-regulating? –The Law of Diminishing Returns Abundance Total Harvest Abundance Hunter Effort Abundance Harvest Rate

13. Harvest Additive v. Compensatory Mortality

14. Harvest Additive v. Compensatory Mortality –Temporal studies Harvest Mortality Rate Annual Survival Rate A Harvest Mortality Rate Annual Survival Rate B C c = critical threshold

15. Harvest Additive v. Compensatory Mortality –Large scale experiments –S Hunting = S No Hunting –Late season harvest

16. Harvest Additive v. Compensatory Mortality –Management implications Harvest as compensatory mortality –Doomed surplus –Harvestable surplus Murray and Frye (1964)

17. Harvest When density independent factors are controlling populations –Harvestable surplus? K N Time

18. Harvest What if we don’t know enough? What if regulations are impractical?

19. Harvest Harvest Management (Ideal) –Determine the status of the resource –Determine the objectives & goals –Establish management strategies –Determine how closely the management strategy achieved the objectives & goals –Adjust management strategies Adaptive harvest management

20. Harvest Harvest Management –Determine the status of the resource Research & monitoring –Mandatory reporting –Check stations –Surveys –Large scale studies

21. Harvest Harvest Management –Determine the objectives & goals Biological, social, economic, & enforcement considerations –Increase, decrease, maintain, or stabilize population size* »Wildlife viewing, hunting, fishing, etc. »Wildlife damage »Wildlife disease (e.g., CWD, rabies) »Habitat & community effects (e.g., brain worm) »MSY or OSY »Quality v. quantity

22. Harvest Managing for the hunter, fisher, or trapper –Quality v. quantity E.g., QDM –Deer, habitat, & experience (U.S Fish & Wildlife Service)

23. Harvest Harvest Management –Establish management strategies Seasons –Opening day phenomenon Bag limits Methods Sex & age taken Permits Areas Effects on and of farming, timber, & non-consumptive wildlife uses Safety Enforcement

24. Harvest Harvest Management –Determine how closely the management strategy achieved the objectives & goals Research & monitoring –Mandatory reporting –Check stations –Surveys –Large scale studies

25. Harvest Harvest Management –Adjust management strategies & start again Adaptive management History, Trial & Error, and Human Dimensions

26. Harvest Harvests can stabilize populations –A management tool N Time

27. Harvest Economics: Billions of dollars & hundreds of thousands of jobs! Costs of not harvesting

28. Harvest Illegal taking (poaching) –Equal to the legal harvest? –Fair chase? –This is not hunting! –Implications Population & habitat management –SY considerations –Estimate illegal take

29. Harvest Differential Vulnerability –Sex –Age Mating habits –Effects on sex ratios & age structure Productivity

30. Harvest Differential Vulnerability –Flook (1970): Unhunted elk Sex ratio of newborn calves: 100:100 Sex ratio of yearlings:131:100 Sex ratio of  2 year olds: 31:100 Why? –Fat, teeth, mating system

31. Harvest Differential Vulnerability –Hunted black bears Sex ratio of population: 72:100 Sex ratio of harvest:145:100 Why? –Movements: male home range size = 30.8 km 2 female home range size = 5.2 km 2 –Harvest technique: 4% of harvest using bait is female 40% of harvest using dogs is female –Harvest timing: denning Management

32. Harvest Differential Vulnerability –Management implications Sex & age structure Mating habits

33. Harvest Federal v. state management Public v. private lands –Private lands harvest management initiatives