Asian Carp Removal from Chicago Area Fishing Ponds and Potential Sources of Their Introduction

Verified occurrences of Asian carp in impoundments have been documented throughout the United States.  In Illinois, 32 Bighead Carp (Hypophthalmichthys nobilis) have been removed from five Chicago area fishing ponds by the Illinois Department of Natural Resources since 2011.  Three additional Chicago area fishing ponds, as well as four ponds downstate, have verified captures of Asian carp from either sampling, pond rehabilitation or natural die-offs.  All but one of these ponds is isolated with no surface water connection to Lake Michigan or the Chicago Area Waterway System.  The results of otolith chemistry analysis suggest that these fish were likely incidentally stocked during age-0 or age-1 as contaminants in shipments of Channel Catfish (Ictalurus punctatus).   This corresponds to a time when Bighead Carp were raised in aquaculture ponds with Channel Catfish in certain regions of the U.S and before the State of Illinois banned transport of live Bighead Carp in 2002-2003.  We recommend that other states, particularly those within the Great Lakes basin, monitor ponds that may have been stocked with co-mingled populations of Channel Catfish and Asian carps in order to eliminate this as an alternative pathway for Asian carp introduction into the Great Lakes and other waterways.