On October 16 and 17, 2018, nearly 60 scientists and managers met at a workshop in Milwaukee, WI to discuss research needs for Lake Michigan. The workshop, sponsored by the International Joint Commission through its Science Advisory Board Research Coordination Committee and organized by Illinois-Indiana Sea Grant, was part of the Cooperative Science Monitoring Initiative (CSMI). The main purpose of the meeting was to kick off discussions about research priorities to be considered during the 2020 CSMI intensive field year on Lake Michigan. This document summarizes the meeting proceedings.

The role of the Cooperative Science and Monitoring Initiative (CSMI) is to provide enhanced monitoring and research activities that provide relevant information to address the science priorities of the Lake Partnerships (established under the Lakewide Management Annex of the 2012 Great Lakes Water Quality Agreement) across the Laurentian Great Lakes. The Lake Michigan Partnership, a collaborative team of natural resource managers led by the U.S. Environmental Protection Agency with participation from federal, state, tribal, and local governments or agencies, uses the information collected through CSMI to help develop long term ecosystem-based management strategies for protecting and restoring Lake Michigan’s water quality. On a practical level, CSMI is an intensive effort to collect information on the health of each lake, rotating to one Great Lake each year. In 2015, it was Lake Michigan’s turn. This is an executive summary of the 2015 research results and the associated white paper containing more specific information.

This session was one of the largest at the 60th annual IAGLR conference, with 18 oral presentations, 1 poster presentation, and 1 facilitated discussion period. The full list of abstracts (with author contact information) is included as Appendix 1. This session was well-attended throughout the day, with as many as 70 people attending the individual talks.

Ecological complexity may improve ecosystem function, stability and adaptability to natural and anthropogenic disturbances. Intraspecific trophic variation can represent a significant component of total community variation and can influence food web structure and function. Thus, understanding how trophic niches are partitioned between intraspecific and interspecific processes could improve our understanding of food web dynamics.

We examined gut contents, fatty acids and stable isotope ratios in round goby (Neogobius melanostomus) and yellow perch (Perca flavescens) across six sites in Lake Michigan, USA, to determine patterns in intra‐ and interspecific trophic composition (i.e., mean gut or fatty acid composition) and diversity (i.e., the diversity of gut items or fatty acids). We also examined relationships between fatty acid diversity and gut content characteristics to understand potential mechanisms shaping individual trophic phenotypes. There was significant variation in both trophic composition and diversity among sites, and individual and spatial variation was as important to total trophic variation as species identity. Round goby that consumed dreissenid mussels had more diverse fatty acid profiles than those that consumed other benthic invertebrates, whereas yellow perch fatty acid diversity was not related to gut content composition. Our results confirm that intraspecific variation in resource use can be as important to trophic dynamics as interspecific variation, and that spatial variation in lower level food web processes or habitat may strongly structure local food web dynamics. Individual‐level examination of trophic diversity, in concert with trophic composition, could provide additional information about the resilience, function and adaptability of local food webs.

Document available through publisher’s website: 10.1111/eff.12472

This extension publication intends to educate audiences on Lake Michigan ecosystem changes and their effect on target species such as salmon and trout. This may provide audiences with a better understanding on key management strategies (e.g., decreases in salmon stocking rates) used by state fisheries agencies. Additionally, an increased understanding of what salmon and trout are eating in Lake Michigan may help anglers better target these species, which may increase catch rates and overall enjoyment of fishing.

This document is available through the Purdue University Extension Education Store at https://edustore.purdue.edu/item.asp?Item_Number=FNR-565-W