Bycatch, bait, anglers, and roads: quantifying vector activity and propagule introduction risk across lake ecosystems. Issue 4 (1st June 2014)

• Record Type: Journal Article
• Authors: Drake, D. Andrew R.; Mandrak, Nicholas E.
• Is Part Of: Ecological applications. Volume 24:Issue 4(2014)
• Page Start: 877
• Page End: 894
• Publication Date: 2014-06-01
• Subjects: aquatic ecosystems -- fishing -- gravity model -- invasive species -- propagule pressure -- social-ecological model -- spread -- transportation network; Ecology -- Periodicals; Environmental protection -- Periodicals; Biology, Economic -- Periodicals; 577.05
• DOI: 10.1890/13-0541.1
• Languages: English
• ISSNs: 1051-0761

Abstract

Abstract : Long implicated in the invasion process, live‐bait anglers are highly mobile species vectors with frequent overland transport of fishes. To test hypotheses about the role of anglers in propagule transport, we developed a social‐ecological model quantifying the opportunity for species transport beyond the invaded range resulting from bycatch during commercial bait operations, incidental transport, and release to lake ecosystems by anglers. We combined a gravity model with a stochastic, agent‐based simulation, representing a 1‐yr iteration of live‐bait angling and the dynamics of propagule transport at fine spatiotemporal scales (i.e., probability of introducing n propagules per lake per year). A baseline scenario involving round goby ( Neogobius melanostomus ) indicated that most angling trips were benign; irrespective of lake visitation, anglers failed to purchase and transport propagules (benign trips, median probability P = 0.99912). However, given the large number of probability trials (4.2 million live‐bait angling events per year), even the rarest sequence of events (uptake, movement, and deposition of propagules) is anticipated to occur. Risky trips (modal P = 0.00088 trips per year; ≈1 in 1136) were sufficient to introduce a substantial number of propagules (modal values, Poisson model = 3715 propagules among 1288 lakes per year; zero‐inflated negative binomial model = 6722 propagules among 1292 lakes per year). Two patterns of lake‐specific introduction risk emerged. Large lakes supporting substantial angling activity experienced propagule pressure likely to surpass demographic barriers to establishment (top 2.5% of lakes with modal outcomes of five to 76 propagules per year; 303 high‐risk lakes with three or more propagules per year). Small or remote lakes were less likely to receive propagules; however, most risk distributions were leptokurtic with a long right tail, indicating the rare occurrence of high propagule loads to most waterbodies. Infestation simulations indicated that the number of high‐risk waterbodies could be as great as 1318 (zero‐inflated negative binomial), whereas a 90% reduction in bycatch from baseline would reduce the modal number of high risk lakes to zero. Results indicate that the combination of invasive bycatch and live‐bait anglers warrants management concern as a species vector, but that risk is confined to a subset of individuals and recipient sites that may be effectively managed with targeted strategies.