Spawning Habitat Selection of Hickory Shad

Abstract

We examined the spawning habitat selectivity of hickory shad Alosa mediocris, an anadromous species on the Atlantic coast of North America. Using plankton tows and artificial substrates (spawning pads), we collected hickory shad eggs in the Roanoke River, North Carolina, to identify spawning timing, temperature, and microhabitat use. Hickory shad eggs were collected by both sampling gears in March and April. The results from this and three other studies in North Carolina indicate that spawning peaks at water temperatures between 12.0°C and 14.9°C and that approximately 90% occurs between 11.0°C and 18.9°C. Hickory shad eggs were collected in run and riffle habitats. Water velocity and substrate were significantly different at spawning pads with eggs than at those without eggs, suggesting that these are important microhabitat factors for spawning. Hickory shad eggs were usually collected in velocities of at least 0.1 m/s and on all substrates except those dominated by silt. Eggs were most abundant on gravel, cobble, and boulder substrates. Hickory shad spawned further upstream in years when water discharge rates at Roanoke Rapids were approximately average during March and April (2005 and 2007), as compared with a severe drought year (2006), suggesting that water flows may affect not only spawning site selection but also the quantity and quality of spawning habitat available at a macrohabitat scale. Using our field data and a Bayesian approach to resource selection analysis, we developed a preliminary habitat suitability model for hickory shad. This Bayesian approach provides an objective framework for updating the model as future studies of hickory shad spawning habitat are conducted.

Received July 16, 2010; accepted February 21, 2011

ACKNOWLEDGMENTS

We thank Nicole Antaya, Jessica Baumann, Jenny Bearden, Christin Brown, Jeffery Buckel, Summer Burdick, Patrick Cooney, Kevin Dockendorf, Robert Graham, Thomas Kwak, Kevin Magowan, Warren Mitchell, Caroline Paulsen, and Kenneth Pollock for help with design, field work, and analysis of this study. We appreciate Ashton Drew for reviewing an earlier draft of this paper. This work was funded by Dominion/ North Carolina Power and the North Carolina Wildlife Resources Commission. The North Carolina Cooperative Fish and Wildlife Research Unit is jointly supported by North Carolina State University, North Carolina Wildlife Resources Commission, U.S. Geological Survey, U.S. Fish and Wildlife Service, and Wildlife Management Institute. Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the U.S. Government.