COMMON CARP ( CYPRINUS CARPIO ) POPULATION CHARACTERISTICS AND RECRUITMENT IN TWO NEBRASKA SANDHILL LAKES

Abstract

Common carp (Cyprinus carpio) are a non-native fish in the United States. Due to their prolific nature, they may have detrimental effects on fish and waterfowl communities, including those of Nebraska Sandhill lakes. Information regarding population structure, age, and growth of common carp in Nebraska Sandhill lakes is lacking. We examined adult common carp populations from Marsh and Pelican lakes on the Valentine National Wildlife Refuge. We described size and age structure, growth, and recruitment patterns for these two populations. Age-frequency histograms revealed consistent recruitment of common carp through age 7 in Marsh Lake but inconsistent recruitment in Pelican Lake. Common carp growth was initially faster in Pelican Lake than in Marsh Lake, likely because of a less dense carp population in Pelican Lake. Pelican Lake contains northern pike (Esox lucius) and largemouth bass (Micropterus salmoides), top-level piscivores, while Marsh Lake contains no predatory fish species. The absence of top-level piscivores preying on age-O common carp may have led to the denser population in Marsh Lake. Further research is recommended to understand fully the role of common carp in Sandhill lake communities.