Discerning invasive species in bait and pond stores using environmental DNA high-throughput sequencing metabarcode assays: angler, retailer, and manager implications

Bait and pond stores are potential yet little-studied vectors for aquatic invasive species (AIS) releases. We tested for AIS and/or illegal native species in 51 bait and 21 pond stores located in three watersheds: western-central Lake Erie (Ohio), Lake St. Clair (Michigan), and Wabash River (Indiana) using targeted environmental DNA (eDNA) metabarcode assays of water samples and morphological identifications. Bait and pond stores were questioned about supply chains and anglers were surveyed about live baitfish use and disposal practices. All (100%) of the bait stores had eDNA detections of unadvertised species, with 61% having native non-bait and 88% having AIS. Thirteen native non-bait species were detected, including walleye, yellow perch, and white sucker. Eleven AIS were detected including: Eurasian ruffe in seven stores (all three watersheds), silver carp in five (all watersheds, including a Lake Erie store in two separate years), and bighead carp in two Lake Erie stores that also had silver carp. Among pond stores, two in Lake St. Clair had bighead carp eDNA, one also contained silver carp, and a Wabash River location had European ide. Unadvertised invasive snails were detected with eDNA in 55% of the pond stores, with four having zebra mussels and two with invasive bryozoans. Illegal native and AIS were widespread, showing no apparent relationship to supply lines. Live baitfish dumping was widely reported in Lakes St. Clair and Erie (35-50%). Consumer behavior and AIS prevalence in bait and pond trades thus appear to pose serious risks for AIS introductions and spread.