Evaluation of Gears for Sampling Different Life Stages of Asian Carp

Bighead carp (Hypophthalmichthys nobilis) and silver carp (H. molitrix), together known as Asian carp, are established throughout much of the Illinois River, but the best gears for monitoring each species are unclear.  Neuston nets were used to sample for Asian carp larvae, whereas a combination of active (boat electrofishing, beach seines, purse seines, cast nets, and midwater trawls) and passive gears (gill nets, fyke nets, mini-fyke nets, and hoop nets) were used to sample juvenile and adult Asian carp during 2011 and 2012.  New gears (pound nets, large diameter hoop nets, and surface-to-bottom gill nets) were also evaluated in 2012.  Asian carp were more abundant in lower reaches than in upper reaches of the Illinois River.  Asian carp larvae were only sampled from the lower Illinois River, but few juveniles were captured, suggesting poor recruitment.  Hoop nets, fyke nets, and trammel nets were most effective at capturing adult bighead carp, whereas electrofishing was most effective at capturing adult silver carp.  Pound nets and surface-to-bottom gill nets were generally effective gears, whereas large diameter hoop nets underperformed relative to traditional hoop nets.  Our results can be used to guide future sampling efforts monitoring the distribution and abundance of Asian carp.