Adaptive Regulation of Waterfowl Harvests Using Incomplete Survey Information

Science Center Objects

The 2011 (Draft) Supplemental Environmental Impact Statement on Migratory Bird Hunting (EIS) offers four alternatives concerning the timing of the regulatory process for setting waterfowl hunting seasons. The no-change alternative involves a process by which most proposals for hunting seasons are developed in response to survey information that becomes available in early summer, such as breeding population size, habitat conditions, and the previous season’s harvest.

PROJECT COMPLETED

Migratory Bird Hunting Stamp
Migratory Bird Hunting Stamp

The Science Issue and Relevance: The 2013 Supplemental Environmental Impact Statement on Migratory Bird Hunting (EIS) offers four alternatives concerning the timing of the regulatory process for setting waterfowl hunting seasons. The no-change alternative involves a process by which most proposals for hunting seasons are developed in response to survey information that becomes available in early summer, such as breeding population size, habitat conditions, and the previous season’s harvest. Therefore, the timetable for setting hunting regulations prior to the opening of seasons in September is very tight. The preferred alternative of the EIS is to advance this timetable by approximately two months to allow more time for public input, to provide more advance notice of the season’s regulations, and to save time money in administering the process. However, the extant Adaptive Harvest Management (AHM) process for assessing resource impacts and identifying an optimal set of regulations would require major modifications to account for the absence of current-year survey information. Without a thorough understanding of the nature of these modifications, the potential impacts of the preferred alternative on migratory bird populations will remain largely unknown.

Methodology for Addressing the Issue: The current AHM protocols for mallards, scaup, and pintails are predicated on the theory of stochastic dynamic optimization, which involves accounting for current resource status in decision making, as well as how current decisions affect future resource status (and thus future decisions). The process involves model-based predictions of the current value or return (e.g., as measured by size of the harvest) of alternative regulatory choices, as well as the value that would be realized from future resource states resulting from decisions made in the present. These predictions are probabilistic due to uncontrolled environmental variation, incomplete control over harvests, and uncertainty over the most appropriate model to describe population dynamics. We propose to use the general framework of Markov decision processes to specify modifications to the current AHM process for mallards and to the passively adaptive harvest strategies for pintails and scaup that would be required under the preferred alternative of EIS. Optimal regulatory strategies will be calculated, and Monte Carlo simulations will be used to evaluate expectations of management performance using a variety of metrics, which can be compared under the current process and that proposed by the EIS. 

Future Steps: The computational platform has been designed and optimal harvest strategies calculated using stochastic dynamic programming. The U.S. Fish and Wildlife Service will be implementing the process in 2016. A final manuscript is currently in journal peer review.

Additional Products:

Boomer, G. S., F. A. Johnson, and G. S. Zimmerman. 2015. Adaptive harvest management: adjustments for SEIS 2013. U.S. Department of Interior, Washington, D. C. 22 pp. (http://www.fws.gov/migratorybirds/CurrentBirdIssues/Management/AHM/AHM-intro.htm)