Detecting aquatic invasive species in bait and pond stores with targeted environmental (e)DNA high-throughput sequencing metabarcode assays: Angler, retailer, and manager implications

Bait and pond stores comprise potential, yet poorly understood, vectors for aquatic invasive species (AIS). We tested for AIS and illegal native species in 51 bait and 21 pond stores from the central Great Lakes (Lake Erie, Ohio and Lake St. Clair, Michigan) and the adjacent Wabash River (Indiana) using environmental DNA (eDNA) metabarcode assays of water samples and morphological identifications. Retailers were questioned about supply chains, and anglers surveyed about baitfish use and disposal. Assays revealed unadvertised species eDNA in 100% of bait stores, with 61% containing illegal native non-bait (totaling 13 species) and 88% having AIS (11 species). Illegal native non-bait species included juvenile walleye, yellow perch, and white sucker eDNA. AIS eDNA included Eurasian ruffe in seven stores (all states), silver carp in five (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 showed European ide. Unadvertised invasive snails were discerned in 55% of pond stores. Four contained zebra mussel eDNA and two had invasive bryozoans. Illegal native species and AIS were widespread, but showed little relationship to the retailers' variable and extensive supply chains. Live baitfish releases were reported by 50% of Lake Erie anglers and 35% in Lake St. Clair. Consumer behavior and AIS prevalence in the bait and pond trades thus pose serious risks for introductions and spread.