Quantifying ensnarement risk of spiny water flea by recreational fishing equipment

Session: Poster Session

Holly Wellard Kelly, Natural Resources Research Institute, University of Minnesota Duluth, [email protected]
Valerie Brady, Natural Resource Research Inst., University of Minnesota Duluth, [email protected]
Donn Branstrator, University of Minnesota-Dul, [email protected]
Josh Dumke, Natural Resources Research Institute, University of Minnesota Duluth, [email protected]

Abstract

Spiny water flea (Bythotrephes longimanus) is an invasive zooplankton present in all five of the Great Lakes and many inland lakes throughout the region. Preventing the spread of spiny water flea (SWF) to uninfested lakes is an important management priority because SWF can reduce the abundance of native zooplankton and alter lake food webs. Movement of recreational fishing gear between lakes may be a primary vector for spreading SWF; however, dispersal mechanisms and risks associated with specific gear types remain unknown. We tested the susceptibility of commonly-used fishing gear to fouling by SWF by simulating the use of 5 gear types (three types of fishing lines, downrigger cables, bait buckets, live wells, and three types of anchor ropes) on two Minnesota lakes. We towed gear along three transects during both daylight and twilight hours and deployed stationary anchor ropes. Ensnarement rates differed significantly by gear type, with anchor ropes ensnaring the fewest SWF and downrigger monofilament lines the most. For some gear types (e.g., live wells), ensnarement rates depended on the time of day. Results will help AIS managers, inspectors, and anglers target their cleaning to gear that is likely to accumulate the most SWF.