American Shad Migratory Behavior, Weight Loss, Survival, and Abundance in a North Carolina River following Dam Removals

Abstract

Despite extensive management and research, populations of American Shad Alosa sapidissima have experienced prolonged declines, and uncertainty about the underlying mechanisms causing these declines remains. In the springs of 2007 through 2010, we used a resistance board weir and PIT technology to capture, tag, and track American Shad in the Little River, North Carolina, a tributary to the Neuse River with complete and partial removals of low-head dams. Our objectives were to examine migratory behaviors and estimate weight loss, survival, and abundance during each spawning season. Males typically immigrated earlier than females and also used upstream habitat at a higher percentage, but otherwise exhibited relatively similar migratory patterns. Proportional weight loss displayed a strong positive relationship with both cumulative water temperature during residence time and number of days spent upstream, and to a lesser extent, minimum distance the fish traveled in the river. Surviving emigrating males lost up to 30% of their initial weight and females lost up to 50% of their initial weight, indicating there are potential survival thresholds. Survival for the spawning season was low and estimates ranged from 0.07 to 0.17; no distinct factors (e.g., sex, size, migration distance) that could contribute to survival were detected. Sampled and estimated American Shad abundance increased from 2007 through 2009, but was lower in 2010. Our study provides substantial new information about American Shad spawning that may aid restoration efforts.

Received August 13, 2013; accepted December 10, 2013

ACKNOWLEDGMENTS

The U.S. Fish and Wildlife Service provided funding for field research. The city of Goldsboro and Cherry Hospital provided access to field sites. We thank everyone that assisted with field research, in particular Dana Sackett, Will Smith, John Bain, Donald Danesi, and Meredith Raabe. Julianne Harris, Derek Aday, Kenneth Pollock, George Hess, and Chris Caudill helped improve previous versions of this manuscript. Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the U.S. Government. This study was performed under the auspices of North Carolina State University Institutional Animal Care and Use Committee permit 10-007-O.