2016 Lakewide Assessment Plan Survey Report Report Number: 2017-04 Suggested Citation: Breeggemann, J. J., T. J. Treska, S. D. Hanson, and R. M. Wehse. 2017. 2016 Lakewide Assessment Plan Survey Report. Green Bay Fish and Wildlife Conservation Office Report number: 2017-04. March 2017 Table of Contents Introduction .................................................................................................................................................. 4 Methods ........................................................................................................................................................ 6 Field Sampling ........................................................................................................................................... 6 Lab Processing ........................................................................................................................................... 6 Data Analyses ............................................................................................................................................ 7 Results ........................................................................................................................................................... 8 Discussion ................................................................................................................................................... 10 References .................................................................................................................................................. 14 Photos from cover: Lifting gillnets onboard the Research Vessel Gaylord Nelson and GBFWCO staff holding a lake trout captured in an LWAP survey gill net. 3 Introduction The history of fishing and fisheries management in Lake Michigan has a storied past with periods of boom and bust within the fisheries and successes and failures within fisheries management. Lake Michigan was formed during the Wisconsin glaciation (the last great ice age) when the Laurentide ice sheet expanded south and covered the entire Great Lakes region with ice advancing into the Lake Michigan basin approximately 26,000 years ago (Larson and Schaetzl 2001; Johnson et al. 1997). Ice from the Laurentide ice sheet began to retreat about 20,000 years ago with the last ice sheets retreating from northern Lake Michigan approximately 12,000 years ago, resulting in the current borders of Lake Michigan (Larson and Schaetzl 2001; Johnson et al. 1997). It is estimated that humans began exploiting the bountiful fish resources available to them in Lake Michigan as early as 3,000‐4,000 years ago with the discovery of fish hooks, spears, gaff hooks that have been found in Native American archeological sites around the lake (Cleland 1982). Earliest evidence of the use of nets for fishing on the Great Lakes dates back 3,000 years ago with the discovery of nets and net weights at an archeological site dated to 630 B.C. (Cleland 1982). Some of the earliest accounts (i.e., from the 17th century) from European settlers in the upper Great Lakes region noted the skill and bountiful catches of the local Native Americans and as more and more European immigrants settled in the region, commercial fishing became a way of life for many on Lake Michigan (Cleland 1982). European immigrants began their commercial fishing operations using seines in near shore environments, but when near shore fisheries declined, fishermen switched to the European designed pound nets (Struwe 2016). Commercial fishing on Lake Michigan was revolutionized around the turn of the twentieth century as steam tugs with mechanical gill net lifters and large scale gill net fisheries became more prevalent (Struwe 2016). By the 1920s, the effect of commercial fishing could be seen as commercial catches of lake whitefish (Coregonus clupeaformis) were 10‐20% of what they once were, lake sturgeon (Acipenser fulvescens) catches dropped from almost 4,000,000 pounds in 1880 to 9,000 pounds in 1922, lake herring (Coregonus artedi)/chub (Coregonus hoyi) fishing had stopped in many ports because none were caught, and fishermen had noted that perch (Perca flavesnces) and sucker (Catostomus spp.) were declining in abundance (Koelz 1926). What were once thought of as inexhaustible fisheries for many species in Lake Michigan left many fishermen looking to catch any species they could sell (e.g., suckers and carp [Cyprinus carpio]). Few fishing regulations combined with a lack of enforcement of those regulations resulted in the collapse of many Lake Michigan fisheries (MIDNR 2017) and the realization for the need for more intensive fisheries management and regulation in the future. As societies throughout the world became more industrialized and global markets formed, the Erie and Welland Canals were created to allow commercial shipping vessels access to all the Great Lakes. The creation of these two canals opened Lake Michigan to an unforeseen blow to the commercial fisheries within its waters. Sea lampreys (Petromyzon marinus), a species native to the Atlantic Ocean, now had a way to bypass Niagara Falls and were first observed in Lake Michigan in 1936 or 1937 (GLFC 2015). As adults, sea lampreys are parasitic, attaching to fish and feeding on that host fish’s blood and bodily fluids (GLFC 2015). While most fish species in the Atlantic Ocean had co‐evolved with sea lampreys and therefore do not die when a sea lamprey attaches, fish species native to the Great Lakes had no defenses against sea 4 lamprey wounds and the results were catastrophic (GLFC 2015). By 1952, only 4,000 pounds of lake trout were harvested by commercial fishermen in Lake Michigan, a mere 0.06% of the weight of lake trout captured annually during the early 1900s (Eschmeyer 1957). Efforts to control sea lamprey began in the 1950s, and by the mid‐1960’s biologists had seen an 80‐90% reduction in the number of adult sea lampreys captured at index weirs (Holey et al. 1995). In an attempt to restore lake trout populations following sea lamprey control, biologists began annual stockings of 1‐2 million yearling equivalents of lake trout in Lake Michigan in the 1960s and increased their stocking efforts to 2.5 million lake trout equivalents annually by the mid‐1970s (Bronte et al. 2008). However, these stockings had little effect as no natural recruitment of lake trout was occurring. Alewife (Alosa pseudoharengus), another species native to the Atlantic Ocean that also gained access to the upper Great Lakes following the creation of the Welland and Erie Canals, became the dominant pelagic forage fish in Lake Michigan by the in the 1950s and 1960s. Alewives have much higher levels of thiaminase, an enzyme that destroys thiamine, than native prey fish species in Lake Michigan (Bronte et al. 2003) and research has shown that reduced thiamine levels in eggs of lake trout results in early mortality syndrome of newly hatched lake trout (Fisher et al. 1996; Bronte et al 2003; Honeyfield et al. 2005). With no top predators in Lake Michigan to act as a means of control, the alewife population exploded, overshot its carrying capacity, and then experienced massive die‐offs in Lake Michigan (Brown 1968). One of the largest die offs resulted in dead alewives being observed along the entire shoreline of Lake Michigan extending from Arcadia, Michigan, south through Indiana and Illinois waters, and ending in Sturgeon Bay, WI (Brown 1968). In hopes to find a way to control alewife populations and possibly create sport fishing opportunities, fisheries managers introduced two salmon species, coho salmon (Oncorhynchus kisutch) and chinook salmon (Oncorhynchus tshawytscha), to Lake Michigan in 1966 and 1967, respectively (Eshenroder et al. 1995). Brown trout (Salmo trutta) and rainbow trout (Oncorhynchus mykiss) were also stocked in Lake Michigan to control alewives and provide fishing opportunities (Eshenroder et al. 1995) resulting in five salmonid species being stocked in the lake. By 1970, five state and federal agencies were stocking millions of salmonids into Lake Michigan each year and a booming sport fishery was created. However, during this time, many state management agencies were managing their waters independently with little collaborative effort between agencies. Furthermore, many management agencies were taking a single‐ species approach to managing their fisheries, meaning their management was focused on a single species of interest (Christie et al. 1987), and that species was chinook salmon. During the 1980s, some managers were proposing a more holistic (i.e., multi‐species or community management) approach to managing fisheries in Lake Michigan (e.g., Christie et al. 1987). However, it wasn’t until the collapse of the chinook salmon population in Lake Michigan in the late 1980s that most fisheries managers around Lake Michigan saw the need for a better understanding of the life history of the species being managed, a shift from single species management to multi‐species management, as well as the need for a collaborative management strategy among all agencies for all of Lake Michigan (Schneeberger et al. 1998). As a result of past management failures, the lakewide assessment plan (LWAP) for Lake Michigan fish communities was proposed by Schneeberger et al. (1998) with the goal of “annually assessing the Lake Michigan fish community in a coordinated, collaborative and standardized fashion”, targeting three key predators: lake trout, chinook salmon, and burbot (Lota lota). 5 Sampling protocols following the