Kevin Layne
Active member
http://www.fws.gov/policy/library/07-1750.html
A. General Harvest Strategy
We propose to continue use of adaptive harvest management (AHM) to help determine appropriate duck-hunting regulations for the 2007-08 season. AHM is a tool that permits sound resource decisions in the face of uncertain regulatory impacts, as well as providing a mechanism for reducing that uncertainty over time. The current AHM protocol is used to evaluate four alternative regulatory levels based on the population status of mallards (special hunting restrictions are enacted for
species of special concern, such as canvasbacks, scaup, and pintails).
In recent years, the prescribed regulatory alternative for the Pacific, Central, and Mississippi Flyways has been based on the status of mallards and breeding-habitat conditions in central North America (Federal survey strata 1-18, 20-50, and 75-77, and State surveys in Minnesota, Wisconsin, and Michigan).
For the 2007 hunting season, however, we are considering setting hunting regulations in the Pacific Flyway based on the status and dynamics of a newly defined stock of "western'' mallards. For now, western mallards would be defined as those breeding in Alaska (as based on federal surveys in strata 1-12), and in California and Oregon (as based on state-conducted surveys).
Efforts to improve survey designs in Washington State and British Columbia are ongoing, and mallards breeding in these areas would be included in regulatory assessments when a sufficient time-series of abundance estimates is available for analysis. Predicting changes in the abundance of western mallards due to harvest and uncontrolled environmental factors would be based on a model of density-dependent growth, with appropriate allowances for model uncertainty and the impact of hunting.
Various harvest-management objective(s) for western mallards are being considered but, in any case, would not allow for a harvest higher than the estimated maximum sustainable yield. More specifics concerning this proposed change in AHM protocol are available on our website at http://www.fws.gov/migratorybirds/mg.../AHM-intro.htm and will be provided in a supplemental proposed rule in May along with Flyway Council recommendations and comments. The final AHM protocol for the 2007-08 season will be detailed in the early-season proposed rule, which will be published in July (see Schedule of Regulations Meetings and Federal Register Publications at the end of this proposed rule for further information).
Finally, since 2000, we have prescribed a regulatory alternative for the Atlantic Flyway based on the population status of mallards breeding in eastern North America (Federal survey strata 51-54 and 56, and State surveys in New England and the mid-Atlantic region). We are recommending a continuation of this protocol for the 2007-08 season.
We will propose a specific regulatory alternative for each of the Flyways during the 2007-08 season after survey information becomes available in late summer. More information on AHM is located at http://www.fws.gov/migratorybirds/mg.../AHM-intro.htm
Pintails
In collaboration with scientists from the U.S. Geological Survey, progress has been made in the development of a compensatory harvest-mortality model for pintails. The model predicts that pintail survival during the period following the hunting season is density-dependent, and represents an alternative hypothesis about the effect of hunting mortality on pintail population change.
We are considering the inclusion of a "strong'' compensatory model as a competing model in the analytical framework used to prescribe harvest regulations under the current pintail harvest strategy.
Presently, in the current pintail harvest strategy, hunting mortality is assumed to be "additive'' to natural forms of mortality. Predictions of pintail population size derived from the additive and compensatory models will be compared to the results of past population surveys to determine the initial predictive reliability of each alternative model. These comparisons will be used to weight each model in a manner that reflects past predictive ability. Model weights determine the influence that the alternative harvest-mortality models will have on subsequent regulatory decisions.
Model weights will be updated annually by comparing model predictions with survey results such that the model with greater predictive ability exerts greater influence in regulatory decisions over time. We remain committed to the development of a framework to inform pintail harvest management based on a formal, derived strategy and clearly articulated management objectives.
Scaup
In 2006, we did not change scaup harvest regulations with the understanding that a draft harvest strategy would be available for Flyway Council review prior to the 2007 winter meetings (see September 22, 2007, Federal Register, 71 FR 55654). In response to this expectation, we have developed models to represent scaup population and harvest dynamics that rely on the available scaup monitoring information and account for uncertainties about factors affecting scaup population change. The details of the models and assessment methods used to derive a scaup harvest strategy were presented during the Winter Flyway Technical Section meetings and a summary is available at http://www.fws.gov/migatorybirds/reports. As part of the strategy-development process, we provide several example harvest strategies based on a range of potential harvest-management objectives in order to solicit feedback regarding the appropriate objective for scaup harvest management.
The final scaup harvest strategy will be detailed in the July early-season proposed rule (see Schedule of Regulations Meetings and Federal Register Publications at the end of this proposed rule for further information).
