AUTHORS: Adam J. McFall, USGS; Jacob D.A. Faulkner, USGS; Andrew T. Mueller, USGS; Curt G. Byrd, USGS; Robin D. Calfee, USGS
ABSTRACT: Invasive carp continue to spread throughout U.S. waterways, threatening native fishes and disrupting ecosystems, yet effective removal methods remain limited. Fish herding methods are used to aggregate carp for removal; however, location, timing, and personnel constraints limit the effectiveness of herding for eradicating carp populations. Baiting and chemical attractants have also been shown to aggregate invasive Bighead Carp (Hypophthalmichthys nobilis) and Silver Carp (Hypophthalmichthys molitrix) in laboratory settings, but in situ applications are still being tested. Acoustic attractants are an understudied tool that could help aggregate invasive carp for removal in situ. Conspecific feeding sounds attracted Bighead Carp in preliminary laboratory trials. Grass Carp (Ctenopharyngodon idella) have similar life history strategies, but their response to conspecific feeding sounds have not been evaluated. We examined whether conspecific feeding sounds affect the behavior of Grass Carp. Grass Carp were randomly exposed to three treatments: conspecific feeding sound (projection via underwater speaker), feed (pelleted feed distributed via automatic feeder), and a control (no sound or food). Two trials, each consisting of 12 distinct exposures (four exposures per treatment), were duplicated in two outdoor earthen research ponds (0.09 ha) at the Columbia Environmental Research Center. Fish (n = 29 – 30 per trial) were implanted with acoustic transmitters and distributed evenly in the ponds, where fine scale (< 1 m) positions were recorded by a hydrophone array from 13 May 2024 – 17 May 2024 (Trial 1) and 3 June 2024 – 7 June 2024 (Trial 2). Preliminary results show that total displacement and swimming speed were generally higher following feed and sound treatments compared to control treatments. Fish also spent more time near the feeders, speakers, and in deep water compared to other areas of the ponds. Here we discuss future research needs and how this technology could be utilized in invasive carp management programs.
