Age, Growth, and Reproduction in Two Coastal Populations of Longnose Gars

Abstract

Measurements of age, growth, and reproduction are excellent tools for determining the ecological role and impact of a species within an ecosystem. Longnose Gar Lepisosteus osseus is a large, ubiquitous top predator in fresh and saline waters of the eastern United States. Even though the species is common, their basic biology has been largely uncharacterized in brackish and marine waters. Specimens were collected from two estuaries: Winyah Bay and Charleston Harbor, South Carolina, from May 2012 through July 2013 to examine age, growth, and reproduction in tidally influenced systems. This species is fairly long-lived, with maximum ages of 17 and 25 years for males and females, respectively. The von Bertalanffy growth model yielded significantly higher growth rates for males than for females. Reproductive histology and the gonadosomatic index indicated that Longnose Gars exhibit determinate fecundity and spawn in late spring following a long development period during fall and winter. These life history parameters provide valuable insight into the basic biology of Longnose Gars and into how they function in estuarine environments. Further research on the precise timing and location of spawning movement, as well as daily movement patterns of this species, would provide a more comprehensive knowledge of Longnose Gar reproductive biology.

Received May 18, 2015; accepted October 9, 2015

ACKNOWLEDGMENTS

Thanks to Bill Roumillat and Patrick Biondo for their expertise in fish reproduction, David Buckmeier for his advice and input on gar aging, the Inshore Fisheries Division of the SCDNR for sample collection, processing assistance, and support, and the Mariculture Division of the SCDNR for additional sample collection. Funding for this work came from the following: the U.S. Department of Energy through the Nuclear Workforce Initiative of the SRS Community Reuse Organization (V. Shervette), the University of South Carolina Aiken Department of Biology and Geology (V. Shervette), and the Joanna Deep Water Fund Fellowship (M. Smylie). This is contribution 742 from the Marine Resources Research Institute of the SCDNR.