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Lesser scaup (Aythya affinis) and greater scaup (A. marila), hereafter scaup, consume a variety of aquatic invertebrates, plants, and occasionally small fish. Scaup have foraged on commercial aquaculture farms in the southern United States for decades. However, the types, abundance, and rate of fish exploitation by scaup on baitfish and sportfish farms are not well documented. Thus, information is needed to understand how fish and other foods influence scaup use of aquatic resources, and any potential economic effects of depredation of fish. From November-March in winters 2016-2017 and 2017-2018, we conducted 1,458 pond surveys to estimate the abundance and distribution of scaup on Arkansas baitfish and sportfish farms that commercially produce species such as golden shiners (Notemigonus crysoleucas), fathead minnows (Pimephales promelas), goldfish (Carassius auratus), and sunfish (Lepomis spp.). We also collected and processed 531 foraging scaup and quantified the proportion of scaup consuming fish and the proportion of their diet obtained from fish. Fish consumption was highly variable between years. In our survey area, we estimated total fish consumption at 1,400 kg and 60,500 kg for winters 2016-2017 and 2017-2018, respectively. Sunfish ponds experienced the maximum loss (18,000 fish/ha) during winter 2017-2018, while goldfish ponds experienced a loss of just 2,600 fish/ha during the same winter. The estimates of baitfish and sportfish loss to scaup revealed potential management strategies for minimizing fish loss and can inform economic analysis of the financial impact of scaup on producers. (c) 2021 The Wildlife Society. U.S. Department of Agriculture National Institute of Food and AgricultureUnited States Department of Agriculture (USDA) [2016-38500-25752]; Forest and Wildlife Research Center (FWRC), Mississippi State University Published version Funding was provided by the Southern Regional Aquaculture Center through Grant number 2016-38500-25752 from the U.S. Department of Agriculture National Institute of Food and Agriculture. We are thankful for the USDA/APHIS/WS National Wildlife Research Center-Mississippi Field Station for providing staff, vehicles, and a host of other supplies that made the completion of this study possible and the UDSA/APHIS Wildlife Services in Arkansas for their assistance in bird collections and facilitating contact with producers. We thank the Forest and Wildlife Research Center (FWRC), Mississippi State University, for support. We thank M. Colvin and K. Evans for revisions on a previous draft, and E. Rigby (Associate Editor), A. Knipps (Editorial Assistant), and 2 anonymous reviewers for their critical reviews, which improved the manuscript. We especially thank the baitfish and sportfish producers of Arkansas that allowed us access to their facilities and generously provided us with the information needed to complete the analysis. The findings and conclusions in this publication are those of the authors and should not be construed to represent any official USDA or U.S. Government determination or policy. Public domain – authored by a U.S. government employee |
