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Monday, January 25 • 1:40pm - 2:00pm
Upstream-Downstream Variation In Silver Carp Life-History Traits Along An Invasion Front

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AUTHORS: Christopher Sullivan*, Department of Natural Resource Ecology and Management, Iowa State University, Carlos Camacho, Department of Natural Resource Ecology and Management, Iowa State University, Michael J. Weber, Department of Natural Resource Ecology and Management, Iowa State University , Clay L. Pierce, Department of Natural Resource Ecology and Management, Iowa State University and U.S. Geological Survey

ABSTRACT: Longitudinal gradients in river morphology can influence life-history traits of fish populations. Since the 1970s, silver carp Hypophthalmichthys molitrix have spread throughout the Mississippi River basin and are currently expanding into interior Iowa rivers. Under range expansion, life-history traits are expected to differ from central to peripheral populations (e.g., smaller individuals and skewed sex ratios for peripheral populations) which may influence population establishment and growth. To test this hypothesis, silver carp life-history traits were evaluated along an upstream-downstream invasion front (northern edge of range, adults present and reproduce but no known recruitment). Silver carp were collected with daytime electrofishing from April – September 2014/2015 at five locations along the Des Moines River and at the Mississippi River confluence. Mean catch per unit effort ranged from 8.2 to 434.0 fish/hour (mean = 70.8, SD = 110.4) but were not related to river location. At downstream sites, silver carp were generally larger, fish grew faster, and sex ratios were skewed towards females compared to upstream sites. However, silver carp GSI and condition were unrelated to river location. Our results suggest that silver carp populations display variations in life-history traits along longitudinal gradients which may be an important component of successful range expansion into novel systems. After initial establishment, silver carp colonization into novel river reaches free of barriers (e.g., dams) may require different life-history traits than those required to maintain a viable, self-sustaining population.

Monday January 25, 2016 1:40pm - 2:00pm
Pantlind

Attendees (15)