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533 Re-Establishing Lake Trout in the Laurentian Great Lakes: Past, Present, and Future Andrew M. Muir, Charles C. Krueger, and Michael J. Hansen Lake Trout (Salvelinus namaycush) were native to the Laurentian Great Lakes (hereafter, Great Lakes) and were widely distributed throughout lakes Superior, Michigan, Huron, and Ontario and the eastern basin of Lake Erie (fig. 1). Prior to European colonization, Lake Trout were an important resource for aboriginal peopleslivingaroundtheGreatLakes(Bogue2000).EuropeancolonizationoftheLaurentianBasin,during the eighteenth and nineteenth centuries, resulted in rapid expansion of Lake Trout fisheries. Colonization also brought about dramatic changes to landscapes, which, ultimately, had devastating and long-lasting effects on the ecology of watersheds. Forestry and shipping were two destructive practices that, when combined with rapidly expanding commercial fisheries, drove Lake Trout populations into decline by the early 1900s. Sea Lamprey (Petromyzon marinus), a voracious parasitic predator of fishes, invaded the Great Lakes via shipping channels and, ultimately, led to the demise of several Lake Trout populations, during the late nineteenth and early twentieth centuries. By the late 1950s, native Lake Trout were gone from Lakes Ontario, Erie, and Michigan, nearly so from Lake Huron, and at low levels in most near shore locations in Lake Superior. In response to these collapses, fishery management during the mid-1900s aimed to control fishing mortality, mitigate habitat loss and changes to native food webs, control non-native species invasions, conserve remnant stocks, and, ultimately, rehabilitate Great Lakes Lake Trout populations. Fisheries regulations, invasive species control programs, stocking, research, and assessment programs were among the tools used within a binational context. In this chapter, the history and current status of Lake Trout fisheries in the Great Lakes, their management, and efforts toward reestablishment is reviewed and future management is discussed within the context of historical lessons learned. Information from two previous reviews, one by Hansen (1999) published in the first edition of this book and a second by Krueger and Ebener (2004) published in Boreal Shield Watersheds: Lake Trout Ecosystems in a Changing Environment is consolidated and updated. Our specific objectives were to (1) review the history of Lake Trout fisheries and their management in the Great Lakes, (2) describe new and ongoing management actions to achieve Lake Trout rehabilitation goals, and (3) review lessons learned and describe emerging research themes that support Lake Trout rehabilitation. FIG. 1. Laurentian Great Lakes showing Lake Trout (Salvelinus namaycush) refuges. RE-ESTABLISHING LAKE TROUT 535 This review is structured according to our three objectives, and, within each section, the information is organized by lake. Herein, we define “reestablishment” as “reintroduction followed by long-term persistence of populations through natural reproduction” (Zimmerman and Krueger 2009) and use the term synonymously with the term “rehabilitation.” By invoking the term reestablishment, we explicitly acknowledge that native Great Lakes communities have been irrevocably altered and that management and recovery expectations must be founded within that context (Zimmerman and Krueger 2009). Reestablishment differs markedly from “restoration,” which infers recovery to previous historical conditions, an unachievable goal. Because historic Lake Trout population structure is unknown and contemporary structure is largely influenced by stocking and past exploitation on remnant populations, the terms “stock” and “population” are used interchangeably to refer to a local group of individuals that form a potentially interbreeding group. Our review of rehabilitation management is premised on our contemporary understanding of the historical Lake Trout diversity that once existed within the Great Lakes or may be inferred from extant diversity in Great Bear and Great Slave Lakes (Blackie et al. 2003; Alfonso 2004; Zimmerman et al. 2006). As such, a brief description of that diversity is warranted to set the stage for the remainder of the review. Historic Lake Trout Diversity Aboriginal peoples, Jesuit missionaries, French voyageurs, commercial fishermen, and naturalists identified several different forms of Lake Trout in the Great Lakes (e.g., Agassiz 1850; Goodier 1981; Jordan and Evermann 1911; Roosevelt 1865). These types are referred to as “morphs,” which we define as a “form or variant” (Coad and McAllister 2010). Lake Trout morphs appear to have arisen multiple times and have been maintained by isolated spawning habitats and feeding specializations. For example, within the Great Lakes, adfluvial populations lived a portion of their life in the lake, but returned to rivers to spawn (Loftus 1958), whereas lacustrine populations lived and spawned entirely within the lakes. The lacustrine morph was further subdivided into shallow- and deepwater types. Shallow-water morphs, referred to as “leans,” typically occupied water shallower than 70 m, whereas the deep...

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