The following schedule is from the 72nd Annual Conference of the Southeastern Association of Fish & Wildlife Agencies which was held October 21-24, 2018 in Mobile, Alabama.
AUTHORS: Terrel W. Christie, J. Brian Davis – Mississippi State University; Brian S. Dorr; Katie C. Hanson-Dorr – USDA National Wildlife Research Center; Luke A. Roy, Auburn University; Anita Kelly, University of Arkansas-Pine Bluff; Carole Engle, Virginia Polytechnic Institute and State University
ABSTRACT: Double-crested Cormorants (Phalacrocorax auritus) impact United States commercial aquaculture and are considered the greatest avian predators at catfish (Ictalurus spp.) aquaculture facilities. Cormorants are especially problematic in western Mississippi, the Delta, where catfish production is concentrated providing ideal wintering and foraging areas. Although cormorant/aquaculture dynamics have been studied in the past, recent changes (e.g., decreased overall hectares in production) in aquaculture practices and regulatory policies merit contemporary research. Therefore, we estimated abundance and distribution of cormorants at their night roosts and assessed diet related to catfish consumption. We used aerial point count surveys flown over night roosts from October through April during two winters, 2016-2018. Following each survey three active night roosts were randomly selected for harvesting cormorants for later necropsy and stomach contents assessment. We completed 25 total surveys and counted 357,850 cormorants (corrected for observer bias). Mean number of cormorants detected per survey, pooled over years, was 14,314 (range 2,964 to 25,624). We collected 730 cormorants from 27 different night roosts across years. Throughout the study catfish comprised 46% of the prey biomass detected with shad (Dorosoma spp.) being the other predominate (45%) prey species. Evidence suggests that the distance between a night roost and the nearest catfish aquaculture facility is an important predictor for a bird’s relative amount of catfish consumption. These results will inform wildlife mangers about relationships between cormorant night roost locations in the Delta and disproportionate consumption of catfish, aiding techniques to help ameliorate fish losses on aquaculture facilities.
