72 the early 1990s in the St. Clair River, a shallow portion of the route from the Atlantic inwards to the Great Lakes where many ships are forced to empty their ballast takes to navigate, economists have determined that the goby were more than likely traveling on Soviet ships, like the zebra mussels were.13 Unlike Zebra Mussels, their spread across the region has been relatively slow across the board. Being that they are fish, it is much more difficult to accidentally transport them from one body of water to another, and for this reason they have remained invasive almost entirely to Michigan, and more recently to the Mississippi River watershed, including the Fox River.14 2015 was the first time that a Round goby was discovered in the Fox River. This discovery has forced the closing of the lock that connects Lake Winnebago to the Fox River to prevent the invasion of the lake which would likely result in their spread to the Wolf River and across the state.15 The Rusty Crayfish was introduced to the Fox River not through large-scale, intercontinental travel, but because of individual fishing negligence. With a native range much closer to the Fox River, many fishermen who frequent the native range also frequent the invasive range of the crayfish.16 For this reason, the accepted consensus on how the Rusty Crayfish ended up in the Fox River and almost all of its other non-native zones is through transportation by angler fisherman who intended to use it as bait.17 The species works well as bait, so fishermen who did not understand the impact that they would be having on the ecology of the Fox River introduced it. Although there is 13 Harold M. Mayer, “Great Lakes--Overseas an Expanding Trade Route,” Economic Geography 30, no. 2 (1954): p. 117, https://doi.org/10.2307/142099 . 14 “Zebra Mussel (Dreissena Polymorpha) - Species Profile,” USGS Nonindigenous Aquatic Species Database, accessed November 13, 2022, https://nas.er.usgs.gov/queries/factsheet.aspx?speciesID=5. 15 Patty Murray, “Invasive Round Goby Fish Discovered in Fox River,” Wisconsin Public Radio, September 7, 2015, https://www.wpr.org/invasive-round-goby-fish-discovered-fox-river. 16 H.H. Hobbs, Joan P. Jass, and Jay V. Huner, “A Review of Global Crayfish Introductions with Particular Emphasis on Two North American Species (Decapoda, Cambaridae),” Crustaceana 56, no. 3 (May 1989): pp. 299-316, https://doi.org/10.1163/156854089x00275. 17 Christopher A. Taylor and Michael Redmer, “Dispersal of the Crayfish Orconectes Rusticus in Illinois, with Notes on Species Displacement and Habitat Preference,” Journal of Crustacean Biology 16, no. 3 (August 1996): p. 547, https://doi.org/10.2307/1548745.
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