SESSION B:

Title: Modeling the distribution of naturally fishless lakes in Maine using GIS

Authors: Emily G. Schilling¹ (student), Katie E. Degoosh (student)², Cynthia S. Loftin^3
1Department of Wildlife Ecology, University of Maine, 5755 Nutting Hall, Orono, ME 04469-5755; 207-581-1340; emily.schilling@umit.maine.edu
²Department of Wildlife Ecology, University of Maine, 5755 Nutting Hall, Orono, ME 04469-5755; 207-581-1340; katie.degoosh@umit.maine.edu
³USGS Maine Cooperative Fish and Wildlife Research Unit, University of Maine, 5755 Nutting Hall, Orono, ME 04469-5755; 207-581-2843; cyndy_loftin@ umenfa.maine.edu

Abstract:

Due to its glacial history and varied topography, Maine may host the highest concentration of naturally fishless lakes in the Northeast. The aquatic fauna of these systems is unique, because they have evolved in the absence of fish since the end of the Pleistocene. Recognizing the ecological value of fishless lakes, this study was developed to gain a better understanding of their number and distribution in the state of Maine. With over 6000 lakes in the state, and less than one quarter surveyed for fish presence, our objective was to develop a method to remotely assess the likelihood that a given lake is fishless. We used GIS to identify geomorphic and geographical factors (e.g., surrounding slope, connectivity) relating to the fishless condition in Downeast and western-central Maine. Based on these factors, stepwise logistic regression models were built to estimate the likelihood that a particular lake is fishless. Approximately 100 lakes were predicted to be fishless in the two study regions. A subset of lakes predicted to be fishless was visited to confirm current and historical fish absence using gillnetting and paleolimnological techniques. The models proved to be highly accurate in predicting fishless lake location. However, many historically fishless lakes were found to contain fish currently due to recent stocking activities. This emphasizes the importance of identifying the remaining fishless lakes so that their biological integrity can be managed appropriately.