Identifying Relationships between Catches of Spawning Condition Yellow Perch and Environmental Variables in the Western Basin of Lake Erie

Although the reproductive behavior of yellow perch Perca flavescens has been well documented in small systems, relatively little is known about the spawning preferences of yellow perch in large systems, such as the Laurentian Great Lakes. During 2006 and 2007, we compared the presence and abundance adult yellow perch during the spring spawning season with environmental variables in the western basin of Lake Erie. We also estimated the timing of yellow perch spawning by comparing the relative abundance of gravid and spent females collected in our trawls and then comparing the proportion of gravid females with environmental conditions at our sampling sites. Overall, the probability of catching adult yellow perch and the catch per unit effort increased with increasing bottom temperatures in the spring, whereas the probability of catching gravid females increased with increasing Secchi depth. However, the relationships between our catch metrics and environmental variables were not consistent across years, possibly as a result of the very strong 2003 year‐class, which became first‐year spawners in 2006. We also documented that yellow perch spawning occurred when bottom temperatures were between 11°C and 15°C in the western basin; these temperatures were reached on different dates in different parts of the basin and in different years. Thus, we suggest that management agencies consider basing the start of the commercial fishing season on prevailing bottom temperatures rather than using a set date across years and sites.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/142328/1/tafs0031.pd

Comparative Recruitment Dynamics of Alewife and Bloater in Lakes Michigan and Huron

The predictive power of recruitment models often relies on the identification and quantification of external variables, in addition to stock size. In theory, the identification of climatic, biotic, or demographic influences on reproductive success assists fisheries management by identifying factors that have a direct and reproducible influence on the population dynamics of a target species. More often, models are constructed as one‐time studies of a single population whose results are not revisited when further data become available. Here, we present results from stock recruitment models for Alewife Alosa pseudoharengus and Bloater Coregonus hoyi in Lakes Michigan and Huron. The factors that explain variation in Bloater recruitment were remarkably consistent across populations and with previous studies that found Bloater recruitment to be linked to population demographic patterns in Lake Michigan. Conversely, our models were poor predictors of Alewife recruitment in Lake Huron but did show some agreement with previously published models from Lake Michigan. Overall, our results suggest that external predictors of fish recruitment are difficult to discern using traditional fisheries models, and reproducing the results from previous studies may be difficult particularly at low population sizes.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/141414/1/tafs0294.pd

An assessment of the potential impacts of climate change on the freshwater habitats of Indiana, U.S.A.

Recent climate-driven, physico-chemical changes documented in aquatic systems throughout the world are expected to intensify in the future. Specifically, changes in key environmental attributes of aquatic systems, such as water quantity, clarity, temperatures, ice cover, seasonal flow regimes, external loading, and oxygen content, will undoubtedly have a broad set of direct and indirect ecological consequences. Some anticipated impacts may be similar across different aquatic ecosystems, while others may be system-specific. Here, we review the potential effects of climatic changes for different freshwater habitats within the state of Indiana, USA, a Midwestern state with diverse land and water features. Given this heterogeneity and that the state is among the southernmost states of the US Midwest, evaluation of freshwater habitats of Indiana provides a useful perspective on potential impacts of climate change. In our study, we first review expected or anticipated changes to physico-chemical and habitat conditions in wetlands, lotic systems, small glacial lakes and Lake Michigan. We then highlight anticipated responses of select aquatic biota to these changes. We describe how climatic changes may interact with other anthropogenic stressors affecting freshwater habitats and consider the potential for evolutionary adaptation of freshwater aquatic organisms to mediate any responses. Given anticipated changes, we suggest aquatic ecosystem managers take a precautionary approach broadly applicable in temperate regions to (a) conserve a diversity of aquatic habitats, (b) enhance species diversity and both inter- and intra-population genetic variation, and (c) limit stressors which may exacerbate the risk of decline for aquatic biota

Aquatic Ecosystems in a Shifting Indiana Climate: A Report from the Indiana Climate Change Impacts Assessment

Indiana is home to many types of aquatic ecosystems, including lakes, rivers, streams, wetlands and temporary (ephemeral) pools, which provide habitats for a wide range of plants and animals. These ecosystems will experience changes in water quantity, water temperature, ice cover, water clarity and oxygen content as the state’s temperature and rainfall patterns shift. The plants and animals living in these aquatic ecosystems will undergo changes that will vary based on the species and the specific places they inhabit. It is challenging to know precisely how organisms will respond to changes in climate. Effects on one species create a difficult-to-predict chain reaction that potentially influences other species in the same ecosystem. Some organisms will adapt and evolve to survive, or even thrive, as the climate changes, but they will have to adjust to more than just the changes in climate. They will also respond to changes in a wide variety of other environmental factors that affect them, including invasive species, habitat destruction, contaminants, nutrient runoff, and land management decisions. While these complicated interactions make it challenging to predict the long-term fate of Indiana’s aquatic species, enough is known about climate-related stressors to help managers develop strategies to avoid the most critical outcomes, hopefully avoiding species loss. This report from the Indiana Climate Change Impacts Assessment (IN CCIA) uses climate projections for the state to explore the potential threats to Indiana’s aquatic ecosystems and describes potential management implications and opportunities

Reliability of Bioelectrical Impedance Analysis for Estimating Whole‐Fish Energy Density and Percent Lipids

We evaluated bioelectrical impedance analysis (BIA) as a nonlethal means of predicting energy density and percent lipids for three fish species: Yellow perch Perca flavescens, walleye Sander vitreus, and lake whitefish Coregonus clupeaformis. Although models that combined BIA measures with fish wet mass provided strong predictions of total energy, total lipids, and total dry mass for whole fish, including BIA provided only slightly better predictions than using fish mass alone. Regression models that used BIA measures to directly predict the energy density or percent lipids of whole fish were generally better than those using body mass alone (based on Akaike’s information criterion). However, the goodness of fit of models that used BIA measures varied widely across species and at best explained only slightly more than one‐half the variation observed in fish energy density or percent lipids. Models that combined BIA measures with body mass for prediction had the strongest correlations between predicted and observed energy density or percent lipids for a validation group of fish, but there were significant biases in these predictions. For example, the models underestimated energy density and percent lipids for lipid‐rich fish and overestimated energy density and percent lipids for lipid‐poor fish. A comparison of observed versus predicted whole‐fish energy densities and percent lipids demonstrated that models that incorporated BIA measures had lower maximum percent error than models without BIA measures in them, although the errors for the BIA models were still generally high (energy density: 15‐18%; percent lipids: 82‐89%). Considerable work is still required before BIA can provide reliable predictions of whole‐fish energy density and percent lipids, including understanding how temperature, electrode placement, and the variation in lipid distribution within a fish affect BIA measures.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/141722/1/tafs1519.pd

A Report by the Steering Committee of the 2021 CIGLR Workshop “Lake Erie Central Basin Hypoxia: State of the Science Review and Approaches to Track Future Progress”

In October 2021 the Cooperative Institute for Great Lakes Research (CIGLR) convened a virtual summit to address hypoxia in the central basin of Lake Erie. Forty-one attendees (Appendix I) representing US and Canadian federal, state and provincial agencies, academic partners, and other stakeholder groups reviewed the state of the science and assessed approaches for tracking the future progress of hypoxia extent. This summit was preceded by three webinars focused on: the GLWQA Nutrients Annex subcommittee history and process, current and past monitoring efforts aimed at hypoxia in the lake, and modeling products related to hypoxia. Participants in the summit split into four breakout rooms and discussed questions pertaining to hypoxia in Lake Erie. This report includes a summary of the general themes discussed in the workshops and the resulting set of recommendations.Cooperative Institute for Great Lakes Research, University of Michiganhttp://deepblue.lib.umich.edu/bitstream/2027.42/175563/1/CIGLR Hypoxia Summit Report 2022.pdfSEL

Experimental and field evaluation of otolith strontium as a marker to discriminate between river-spawning populations of walleye in Lake Erie

Otolith microchemistry is a commonly used tool for stock discrimination in fisheries management. Two key questions remain with respect to its effectiveness in discriminating among river-spawning populations. First, do larvae remain in their natal river long enough for their otoliths to pick up that systemâ s characteristic chemical signature? Second, are larval otolith microchemical differences between natal rivers sufficiently large to overcome spatiotemporal variation in water chemistry? We quantified how larval age, the ratio of ambient strontium to calcium concentrations (Sr:Ca), and water temperature influence otolith Sr in both lab-reared and wild-collected Lake Erie walleye (Sander vitreus). Otolith microchemistry shows promise as a spawning stock discrimination tool, given that otolith Sr in larval walleye: 1) is more strongly influenced by ambient Sr:Ca than by temperature; 2) reflects Sr:Ca levels in the natal environment, even in larvae as young as 2 d; and 3) can effectively discriminate between larvae captured in two key Lake Erie spawning tributaries, even in the face of short larval river-residence times and within-year and across-year variation in ambient Sr:Ca.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author

Introduction to the special section: Status and approaches to assess Lake Erie Central Basin hypoxia

Seasonal hypolimnetic hypoxia has occurred in Lake Erie\u27s central basin since at least the 1950s. The 2012 Great Lakes Water Quality Agreement includes a lake ecosystem objective that commits Canada and the United States to minimize the extent of hypoxic zones, with a particular emphasis on Lake Erie. To meet that objective, Canada and the United States adopted a 40% total phosphorus load reduction target for the western and central basins of the lake. To help assess progress in minimizing Lake Erie\u27s hypoxic zones, the Cooperative Institute for Great Lakes Research (CIGLR) convened a virtual summit in October 2021 to update the state-of-knowledge regarding hypoxia in Lake Erie. This special section summarizes the recommendations for monitoring, assessment, modeling and reporting of hypoxia that resulted from the workshop and features five papers that present new information about hypoxia in Lake Erie. Recognizing that hypoxia occurs in other areas within the Great Lakes basin, a paper investigating seasonal drivers of hypoxia dynamics in Muskegon Lake a drowned river mouth that flows into Lake Michigan, is also featured