# Presentation: 223382

## Harvest Management in an Integrated Framework

- Michael C. Runge
- USGS Patuxent Wildlife Research Center

## Outline

- Harvest Management
- Integrating Harvest & Habitat Management
- Multiple Objectives

## Harvest Management

- Oh no, Not Yield Curves Again!

## Carrying Capacity & Harvest

**Recruitment or Mortality**

**Continental Population Size**

- Recruitment

## Sustainable Harvest

**Notes:**
MCMeq2003plot.m, 12/31/2003, 2003 model weights & parameters

## Yield Curve

- Sustainable Annual Harvest

- Equilibrium Population Size (N)

- 0

- N* = K/2

- K

- 0

*r*maxK/4

- h = *r*max

- h = *r*max/2

- h = 0

## Harvest Management

- At least implicitly, since 1995, the dynamics captured by yield curves have been at the heart of our harvest assessments
- The focus on K makes it clear that harvest dynamics really cannot be understood without the context of habitat management

## Integrating Harvest & Habitat Management

## Coherent Models

- If we had a common modeling framework for harvest and habitat management:
- We could understand how habitat management is affecting continental demographics, including harvest potential
- We could understand how harvest management affects the continental population size, and hence, the use of available habitat
- Continental carrying capacity (K) is a useful metric that links harvest and habitat management
- Yield curves are, in fact, an extremely valuable way to look at *habitat* management

## Pintail Harvest Potential

- Latitude-adjusted  BPOP (millions)

- Annual Harvest (thousands)

- Pre-1975
- (53.6)

- Post-1975
- (55.6)

## Yield Curves for Habitat Management

- Equilibrium BPOP

- Sustained Annual Harvest

- Current

- Increase productivity on existing parcels

- Increase capacity on the landscape

- Yield Curves for *Habitat* Management

## Integrated Modeling

- Benefits
- Track changes in habitat (positive or negative) and account for their effects on harvest potential
- Evaluate effects of habitat management on continental demography
- Understand how waterfowl objectives are affected jointly by harvest and habitat management
- Challenges
- Understanding how JV actions affect continental K
- Do we have the institutional structure in place to build integrated models?

## Multiple Objectives

## Current AHM Objective Function

- This is a composite of several objectives, with an implicit method of weighting:
- Maximize annual harvest of MCM
- Maintain sustainable harvest of MCM
- Discourage population size < NAWMP goal
- Don’t allow closure above 5.5M MCM

## Multiple Harvest Objectives

- But the current AHM objective function leaves out many other possible objectives
- Sustainable harvest of other species
- Avoid partial seasons or closure for other spp.
- Encourage hunter participation
- Provide widespread hunting opportunity
- Motivate habitat conservation
- Maintain historical distributions during winter
- And many others...
- Turning Point question

## What are your top TWO objectives for waterfowl harvest management?

- maximize harvest
- keep harvest sustainable for all species
- avoid closed or partial seasons
- maximize the frequency of long seasons
- have relatively stable regulations
- have relatively simple regulations
- keep populations near the NAWMP goals
- motivate hunter participation
- motivate habitat conservation
- other

## Multiple Waterfowl Objectives

- And the larger endeavor adds even more objectives:
- Achieve NAWMP population objectives
- What fundamental goals drive these?
- Minimize costs of habitat conservation
- Engage partners
- Maintain and motivate a traditional hunting culture
- Generate broad public support for wetland habitat conservation
- Etc.

## Trade-offs

- Harvest management is embedded in a broader context with a complex set of objectives
- There are trade-offs among these objectives
- They cannot all be achieved perfectly
- How do we evaluate and balance the trade-offs in setting harvest regulations?
- Do we currently have a framework for this sort of deliberation?

## Coherent Objectives 

- Equilibrium BPOP

- Sustainable Annual Harvest

- Desired Habitat

- Desired Harvest Policy

- Coherent Objectives

- Current Condition

## Summary

## Summary

- Harvest Management
- Yield curves are a valuable tool
- Integrating Harvest & Habitat Management
- Continental K is a valuable common metric
- Coherent models would allow us to understand how harvest potential is changing due to NAWMP activities and other factors
- Multiple Objectives
- Harvest management, let alone integrated management, is a complex multiple-objective problem
- We need a framework to understand and balance the trade-offs among objectives
- Coherent monitoring could arise out of such an integrated framework