Midwest Fish & Wildlife Conference 2016

AUTHORS: Jody Simoes, Michigan Department of Natural Resources; Frank Lupi, Michigan State University

ABSTRACT: Managers, researchers and stakeholders tasked with developing and implementing management plans are often faced with conflicts among management objectives, particularly in support of large diverse systems such as the Great Lakes. Policy decisions and management strategies are further complicated by a lack of Great Lakes angler preference information. Our objective was to inform the development of fisheries management plans in four Great Lakes (Erie, Huron, Michigan and Superior) and Lake St. Clair, using a stated-preference choice model to examine preferred management outcomes of licensed anglers. The model was estimated with survey data from a random sample of anglers (N=1,036, Response rate=36%). We use the model to estimate relative preferences, willingness to make tradeoffs between attributes, and to illustrate likely angler support for Great Lakes management strategies differentiated by emphasis on Pacific salmon, prey base, and risk of ecosystem collapse. Results showed anglers generally expressed stronger preferences for management outcomes related to ecosystem health attributes and recreational opportunity attributes. To facilitate managerial applications of the trade-offs that were quantified, anglers’ willingness to trade-off average fish size for abundance was computed for all key sportfish in each lake. Finally, the model was used to calculate choice probabilities for three hypothetical Great Lakes management strategies that differed in their emphasis on Pacific salmon, prey base, risks of ecosystem collapse and average fish size. In general, choice probabilities for the average angler, which can be interpreted as the average support for management outcomes, were greater for management outcomes favoring a native species emphasis.

AUTHORS: Steven A. Farha*, MSU - Center for Systems Integration and Sustainability; Thomas R. Binder, MSU - Fisheries and Wildlife; John Janssen, UW-Milwaukee School of Freshwater Science; Stephen Riley, USGS - Great Lakes Science Center; J. Ellen Marsden, UVM - Rubenstein School of Environment and Natural Resources; Mike Hansen, USGS - Hammond Bay Biological Station; Charles R. Bronte, U.S. Fish and Wildlife Service; Charles Krueger, MSU - Center for Systems Integration and Sustainability

ABSTRACT: Despite decades of stocking, restoration of self-sustaining Great Lakes lake trout populations has been slow, potentially reflecting an inability of hatchery-reared lake trout to select habitats suitable for successful incubation. We addressed this hypothesis on two spawning reefs in the Drummond Island Refuge (Lake Huron) using a novel acoustic telemetry-based approach whereby sampling effort was apportioned based on behavioral data from tagged adult lake trout, which were used to classify habitats based on presence or absence of individuals during the spawning season. During 2013 and 2014 spawning seasons, 120-20m x 20m sites were physically characterized and surveyed for egg deposition. Incubation success was estimated on a subset of 30 sites each year using an established in situ habitat bioassay. Diver surveys confirmed egg deposition at 21 sites in both years, but not all sites received eggs in both years. Logistic regression models were used to test for relationships between egg deposition and physical habitat characteristics. The relative importance of each habitat characteristic was ranked using Akaike’s Information Criterion (AIC). Initial analyses indicated that substrates selected for egg deposition were more uniform, smaller in diameter, had deeper interstitial depth, and had greater bathymetric slope than sites not selected by the lake trout for spawning. Sites visited by lake trout and selected for egg deposition had the highest incubation success as estimated by our habitat bio-assay, suggesting lake trout were capable of finding suitable spawning habitat within the Drummond Island Refuge. Nonetheless, lake trout spawned on a wide range of substrates, including several sites that were inconsistent with the commonly-accepted lake trout spawning habitat paradigm. Interestingly, these unconventional sites not only received eggs, but also produced viable fry during each year of the study, forcing us to rethink, adapt, and expand our conceptual understanding of what constitutes suitable trout spawning habitat.

AUTHORS: Tyler Buchinger, Michigan State University; Nicholas Johnson, USGS; Weiming Li, Michigan State University

ABSTRACT: Historically, the Great Lakes hosted genetically diverse populations of lake trout Salvelinus namaycush that were specialized to various niches and spawning habitats. Sea lamprey Petromyzon marinus predation, habitat degradation, and overfishing led to near extirpation of lake trout in the early 1950s. Restoration of naturally reproducing and genetically diverse populations of lake trout is now a key management objective for the Great Lakes. However, lake trout restoration is impeded by low natural reproduction in many areas, and low diversity throughout the Great Lakes. Successful reproduction of natural and stocked lake trout has been hypothesized to be hampered in part by an inability to locate and spawn on highly productive reefs. Furthermore, the mechanisms of reproductive isolation that result in genetic diversity remain unclear. Olfactory cues are hypothesized to guide lake trout to spawning reefs and facilitate spawning behaviors, and may mediate reproductive isolation between populations. Here, we highlight recent efforts to characterize the role of olfaction in lake trout reproduction. First, we evaluate the evidence for the hypothesized roles of juvenile, male, and female pheromones. We then present a revised working model of the function of pheromones, and expand the hypothesis to include olfactory imprinting on unique chemical signatures of a rearing environment. We conclude with future research plans and a vision on how olfactory biology can be incorporated into the restoration of lake trout in the Great Lakes.

AUTHORS: Shawn P. Sitar*, Michigan Department of Natural Resources; James E. Johnson, Michigan Department of Natural Resources-retired; Ji X. He, Michigan Department of Natural Resources

ABSTRACT: Lake trout compose a key component of recreational fisheries in the upper Great Lakes and are managed with length regulations. In some areas and years, recreational length limit regulations require anglers to release non-legal sized lake trout. Furthermore, stock assessment models that estimate harvest quotas for lake trout need to account for recreational catch-release mortality. Currently, these models use 15% hooking mortality which was based on the only Great Lakes study conducted in the 1980s. In that study, no lake trout were caught below 50 m and in Lake Superior, anglers frequently catch lake trout deeper, and these fish may experience barotrauma. There is concern among managers and scientists that the 15 % hooking mortality estimate may be too low. In this study, we estimated hooking mortality using mark-recapture data by comparing differential tag return rates between trapnet-caught (control) and angler-caught (treatment) and released lake trout. Furthermore, key factors that may influence hooking mortality were also measured for angler-tagged fish. These included barotrauma symptoms, fish condition at release, water temperature, depth of capture, hook location, and fishing method. During 2010-2013, 2,300 trap net caught (control group) and 1,800 angler-caught (treatment group) lake trout were tagged and released in southern Lake Superior. In west-central Lake Huron, 1,670 trap net caught and 930 angler-caught were tagged and released. Tag recapture data were accumulated between 2010 and 2015. Tag return rates were lower for angler-tagged than trap net-tagged lake in both Lake Superior and Lake Huron. We estimated overall hooking mortality to be more than double that of the 15% rate previously reported. Furthermore, tag returns rates were lower for higher water temperatures and we measured a positive relationship between water temperature and hooking mortality rate. Based partly on these findings, Lake Huron managers decided to minimize use of length-based regulations.

AUTHORS: Jason B. Smith*, Little Traverse Bay Bands of Odawa Indians; Annalise M. Povolo, Michigan Department of Natural Resources Fisheries Division

ABSTRACT: Recent decreases in alewife Alosa pseudoharengus abundance have increased both interest in and opportunity for restoration of Lake Michigan native planktivores such as cisco Coregonus artedi. Anecdotal evidence, including increased recreational and assessment catch, suggest that Lake Michigan cisco stocks are expanding from their current, near historic low, levels of abundance. However, even if the cisco population is expanding, it is possible that successful restoration may require stocking of an appropriate strain or strains. Since 2014, the Little Traverse Bay Bands of Odawa Indians Fisheries Enhancement Facility has released more than 50,000 cisco into Little Traverse Bay. Accurate assessment of the Lake Michigan cisco population is needed both to understand the status of the remnant population as well as to assess the efficacy of current and future stocking efforts. Our lake-wide assessment effort focuses on three areas: (1) gaining a better understand of the life history of the remnant Lake Michigan cisco stock; (2) quantifying population demographics of this stock; and (3) detecting and/or quantifying the effect of the current LTBB Hatchery effort. In spring of 2015, we used shallow set gillnets and beach seines to successfully determine that both juvenile, immature and mature fish inhabit nearshore waters less than 10 meters deep. Lake Michigan cisco appear to become pelagic as spring progresses into summer. Therefore, we are using vertical gill nets, suspended gillnets, hydroacoustic monitoring, and pelagic trawls in an effort to document the extent of their seasonal range within the lake. Our fall sampling effort is aimed at identifying previously unknown spawning reefs throughout Northeastern Lake Michigan as well as collecting eggs for the LTBB Hatchery. Ultimately, we plan to use our increased knowledge of Lake Michigan cisco to construct a long-term lake-wide assessment protocol leading to well informed decisions regarding cisco restoration.

AUTHORS: Patricia Armenio*, David "Bo" Bunnell, David Warner –USGS-GLSC

ABSTRACT: The Lake Huron food-web has undergone fundamental changes since 2002 from declines in primary production to the near collapse of the Chinook salmon fishery.  One native forage fish species, bloater Coregonus hoyi appears to have at least partially benefited from the changing ecosystem.  Bloater consumes both benthic invertebrates and zooplankton and has increased in abundance since the mid-2000s, although its growth and condition appears stunted.  Rainbow smelt Osmerus mordax, a nonnative forage fish, is another dominant prey fish in Lake Huron, although its population trends have trended downward since the 1980s and has been relatively stable in the 2000s.  One possible explanation for the changing fish community is a shift in zooplankton community composition and domination of the benthic invertebrate community by invasive dreissenid mussels (which bloater and smelt cannot consume).  To evaluate which prey species were important to bloater and rainbow smelt consumption, we calculated Vanderploeg’s W´ index of selectivity in Spring, Summer, and Autumn of 2012 at three depths (18 m, 46 m and 82 m) near Hammond Bay and Thunder Bay in northern Lake Huron.  Bloater greater than 90 mm total length (TL) selected mostly for chironomids, Mysis, and also Bythotrephes.  While Mysis is an energetically valuable prey item (i.e., hot dogs), chironomids and Bythotrephes are lower food quality (i.e., potato chips).  These diet selectivities could help explain the truncated size distribution and lower than expected physiological condition of bloater.  Rainbow smelt greater than 80 mm selected mostly for Senecella calanoides, a large calanoid copepod, in Spring and Bythotrephes in other seasons.  Rainbow smelt seem to be more opportunistic and generalist feeders than bloater.  Our research describing forage fish diet and selectivity patterns can be used in future research to better understand changes in growth and production of these two key species in Lake Huron.

AUTHORS: Rick Clark*, Quantitative Fisheries Center, Michigan State University; Reneé Reilly, Quantitative Fisheries Center, Michigan State University; James R. Bence, Quantitative Fisheries Center, Michigan State University; Randall M. Claramunt, Michigan Department of Natural Resources, Charlevoix Fisheries Research Station; John A. Clevenger, Michigan Department of Natural Resources, Charlevoix Fisheries Research Station; Matthew S. Kornis, U.S. Fish and Wildlife Service, Green Bay Fish and Wildlife Conservation Office; Charles R. Bronte, U.S. Fish and Wildlife Service, Green Bay Fish and Wildlife Conservation Office; Charles P. Madenjian, U.S. Geological Survey, Great Lakes Science Center; and Edward F. Roseman, U.S. Geological Survey, Great Lakes Science Center

ABSTRACT: Alewives are preferred food of Great Lakes Chinook salmon. Alewife abundance declined to near zero in Lake Huron (LH) in 2004 and has subsequently remained low. In contrast, alewife abundance in Lake Michigan (LM) has remained comparatively high. We wondered if this abrupt change in relative abundance between lakes affected movement patterns of Chinook salmon. We compared movements before (1993-1997) and after (2008-2014) the alewife collapse using recapture locations of Chinook salmon tagged and released at similar sites in each lake; Medusa Creek in LM and Swan River in LH. Both sites are about 80 kilometers from the boundary between lakes. We aggregated recaptures into seasonal periods; April-July and August-October. Based on the life history of Chinook salmon, we assumed that the primary reason for movements in the first period was feeding and the primary reason for movements in the second period was spawning. We found that over 90% of recaptures in 1993-1997 were from within the same lake where fish were stocked regardless of season. That is, Medusa fish fed in LM and returned to Medusa Creek to spawn, and Swan fish fed in LH and returned to Swan River to spawn. After the collapse of alewives in LH, Medusa fish continued the same pattern, but Swan fish changed their feeding location to LM. Over 90% of recaptures of Swan fish in 2008-2014 were in LM during the feeding season, and the spatial distribution of recaptures was similar to that of Medusa fish. The distribution was centered in the Ludington-Manistee area of LM, more than 250 kilometers from the boundary between the lakes. Fish returned to their respective release sites in the spawning season. We concluded that most Chinook salmon stocked into Northern LH since the collapse of alewives have been feeding in LM.

AUTHORS: Zach Prause*, Ball State University; Thomas Lauer, Ball State University

ABSTRACT: Over the past decade, alewives Alosa pseudoharengus in Lake Michigan have been showing signs of declining overall health and reduced abundance. Because alewives are such an integral part of the Lake Michigan ecosystem, a collapse similar to one seen in a decade ago in Lake Huron is feared. The objective of this study is to identify changes in alewife demographics over time to create possible future trends. Fulton’s condition factor for alewives has declined from an average of 0.83 in the period 1979-1994 to 0.74 in the time period 1994-2012. Recent length-frequency distributions failed to demonstrate a consistent and robust alewife population and are instead showing one or two dominant classes with others being poor or missing. Von Bertalanffy growth curves from the last decade show an overall decrease in growth rate, max length, and max age of fish when compared to growth rates in the 1960s, 1980s, and 1990s. Further, alewife fecundity changes appear to have declined in the most recent years. These composite results identify a scenario In Lake Michigan similar to that shown in Lake Huron in the early part of the 2000s. The shift in alewife abundance and size structure in Lake Michigan in the past two years may alter the predator/prey ratio, ultimately resulting in reduced salmonid abundance.

AUTHORS: Catherine Riseng*, University of Michigan, School of Natural Resources and Environment; Kevin Wehrly, Michigan Department of Natural Resources; James McKenna, USGS, Great Lakes Science Center; Chris Castiglione, U.S. Fish and Wildlife Service; Lizhu Wang, International Joint Commission; Edward Rutherford, NOAA, Great Lakes Environmental Laboratory; Lacey Mason, University of Michigan, School of Natural Resources and Environment; Lucinda Johnson, University of Minnesota, Natural Resources Research Institute

ABSTRACT: We used variables describing depth, thermal regime, and mechanical energy to develop an aquatic ecological classification for waters of the Great Lakes. The classification is developed across aquatic zones including coastal (0-3 meters), nearshore (3-30 meters), and offshore (>30 meters) areas for all five lakes. The nearshore and offshore zones were divided into shallow and deep categories. We calculated cumulative degree-days above zero in the coastal zone using surface temperatures, and in the nearshore and offshore zones using the mean water column temperature of the upper 20 meters. Mechanical energy was described using relative exposure index in the nearshore and coastal areas and dominate spring circulation patterns in the offshore zone. We developed classification thresholds for each of these variables using information from the literature and from a team of Great Lakes’ experts. Our resultant classification contains ~50 unique aquatic ecological units (AEUs) across the entire Great Lakes. Lake Superior and Lake Erie were relatively homogeneous whereas Lakes Michigan, Huron, and Ontario were more complex and contained many more ecological units. Our classification describes the major environmental gradients structuring chemical, physical, and biological factors, and provides a means to simplify and describe the complex array of habitats found throughout the Great Lakes. Because our classification was developed for both U.S. and Canadian waters using the Great Lakes Aquatic Habitat Framework, it provides a common spatial and classification framework for assessing and managing the Great Lakes at the basin scale.