SECOND NORTH AMERICAN SEA DUCK CONFERENCE ABSTRACTS FOR POPULATION DELINEATION PRESENTATIONS 26 ANNAPOLIS, MARYLAND, USA NOV. 7-11, 2005
SECOND NORTH AMERICAN SEA DUCK CONFERENCE DEFINING POPULATION UNITS FOR CONSERVATION OF SEA DUCKS: WHAT ARE WE LOOKING FOR? Dan Esler¹, Sam Iverson¹, John Pearce², and Sandy Talbot² 1 Centre for <strong>Wildlife</strong> Ecology, Simon Fraser University, Burnaby, BC; desler@sfu.ca 2 Alaska Science Center, U.S. Geological Survey, Anchorage, AK Defining population segments as appropriate “management units” is a critical aspect of conservation; the <strong>Sea</strong> <strong>Duck</strong> Joint Venture recognizes this and considers population delineation a high priority as conservation efforts are directed at sea ducks. However, the concept of “management units” is imprecise, and is defined differently by varying parties, following ecological, political, or taxonomic criteria. Based on definitions from the literature, we argue that appropriate management units should be described using population biology concepts, in which management units are aggregations (or spatial scales for continuously distributed species) that are demographically independent, that is, units for which contemporary population dynamics are determined primarily by intrinsic rates of survival and productivity rather than immigration or emigration. We offer examples of these issues using sea ducks and other waterfowl to illustrate the difficulties and importance of defining management units. These issues become much more challenging for migratory species. There may be conservation concerns that require definition of management units separately for different annual cycle stages, or interest in determining whether management units can be described throughout the year. Finally, we conclude that definition of conservation units requires clear consideration of goals at the outset. For example, at what level do we consider population levels demographically independent (dispersal constitutes 1%, 5%, 10%, or 50% of numerical change)? At what geographic scale are we really interested (continental, flyway, state/provincial, local)? What a priori expectations come from our understanding of the history and biology of the species? Finally, what resources are available to address the topic? We suggest that consideration of these issues is long overdue, and hope that these ideas will lead to clarification of definitions surrounding population delineation, and appropriate interpretation of data types commonly used to address these issues. NOV. 7-11, 2005 ANNAPOLIS, MARYLAND, USA 27