The American alligator (Alligator mississippiensis) is found in rivers, lakes, and wetlands of the Gulf and Atlantic coastal plains, from Texas to North Carolina. There is a long history of alligator hunting in this region; however, by 1969 legal harvesting was discontinued in all states after local populations across the species' range dramatically declined and in some cases disappeared. Since then, alligator populations have rebounded due to this restrictive management policy and efforts to conserve wetland habitats in the southeastern U.S. Starting with Louisiana in the 1970s, state harvest programs have been gradually reestablished in eight states. The Georgia, Florida, and South Carolina Cooperative Fish and Wildlife Research Units are collaborating with their respective state wildlife agencies to develop biological models to assist in the selection of harvest regulations.

Today's management approach for alligators is far different from that taken in the pre-moratorium years. Modern harvest regulations are carefully considered on the basis of observed population conditions ? the estimated state of the population based on surveys ? and greater scientific understanding of alligator ecology than was available in the past. Still, there is much that we do not know about alligator population biology and how to determine what level of harvest a population can sustain. In all alligator harvest management programs, allowable take is determined on the basis of annual alligator survey counts. However, not every alligator in the state is counted. Instead, managers visit representative areas and conduct eye-shine surveys on a portion of each area. Managers then track the resulting counts over time to establish a population trend, and that trend is then projected into future years to decide allowable harvest levels.

But just as in investment planning, past performance does not guarantee future results. In addition, there is uncertainty about how reliably counts conducted on parts of selected areas in a region represent the true state of the alligator population, and the relationship between counts and the true population condition may vary among areas. How well we infer the true status of the population from counts factors into harvest management decision-making in much the same way as we factor in our ability to see the road in making decisions about driving a car: how we operate the car on a given stretch of road is likely to be different if we are driving in clear, sunny weather or at night in a heavy rainstorm.

The motivation for this work is a belief that among the alligator populations in each state there are commonalities in the way populations respond to harvest and how well sampling methods relate counts to the true underlying population state. Using past and current monitoring data from the three participating states in conjunction with contemporary modeling approaches and computer processing power, the project team plans to build predictive models of regional alligator populations. These models will be based on the biological mechanisms driving changes in population states over time and will quantify the relationships between the true population state and survey counts.

The team will also work with each state to define its unique harvest management goals and identify its full range of regulatory options. These program elements ? what the agency wants to achieve and its possible actions ? will then be coupled with the biological model ? what the alligator population can sustain ? and optimized to result in condition-dependent, sustainable harvest policies. That is, for any alligator population condition observed in a region (for example, an average count taken from a set of surveys) the harvest decision policy indicates a regulatory action that best pursues the agency's objectives in the short term while ensuring harvestable populations in future years.

This project is ambitious as it will take a lot of hard work, will require specialized tools such as mathematical modeling, statistical estimation, and computational optimization, and is dependent on the cooperation and coordination of many partners. Will the effort be worth it? The team thinks so. The project partners are excited to be involved and for the participating agencies, the outcome will be decision guidance that accounts for the inherent uncertainty in estimates of alligator population sizes and how populations respond to harvest ? important aspects of alligator harvest management that are not sufficiently addressed at the present time. Managers will be able to select regulatory actions based on current observed conditions and the best available science, and these actions will facilitate achievement of management goals in a biologically sustainable manner. Perhaps best of all, the decision framework that develops will be transparent and adaptive, meaning that the agencies can communicate to their public exactly how regulatory actions are derived from observed conditions and that the models will be updated over time based on our improved understanding of alligator population dynamics, respectively. Ultimately, the harvest decision support tools developed by the project team will help state game managers ensure continued public use and enjoyment, and conservation of this charismatic icon of the southeast.

Each month, the ONB features articles from Cooperative Fish and Wildlife Research Units across the country. Working with key cooperators, including WMI, Units are leading exciting, new wildlife research projects that we believe our readers will appreciate reading about.