Natural history and biodiversity—Global biodiversity is being lost at an alarming rate and is one of the greatest threats facing humankind. In the Great Lakes, fishery succession and invasions during the 1800-1900s resulted in tremendous loss of inter- and intraspecific diversity, particularly within deepwater food webs. Effects follow a latitudinal gradient being least in the northern Great Lakes (Superior, Great Slave, and Great Bear) and greatest in the lower Laurentian Great Lakes (Erie and Ontario). My goal is to understand the patterns of diversity and the processes that shape diversity using the northern Great Lakes as model systems and applying knowledge to restoration of impacted lakes, such as Huron, Michigan, Ontario, and Erie. Example applications of this knowledge include stocking a deepwater humper form of Lake Trout Salvelinus namaycush in Lake Erie, recent consideration by Great Lakes fishery managers to culture and stock the blackfin form of cisco Coregonus nigripinnis from outside of the Great Lakes basin, and the recognition that reestablishing the native forage base (deepwater cisco forms) will help restore severed trophic links within the food web. Two ongoing studies contribute to this theme. Data on Lake Trout morphometric, genetic, and life history diversity, and trophic ecology from seven lakes across North America are being analyzed to describe repeated parallel patterns of diversity across the species range. Second, diversity of North American coregonine ciscoes continues to be an important element of my research program and I have recently led an international team to generate a monograph “Ciscoes (Coregonus, subgenus Leucichthys) of the Great Lakes and Lake Nipigon.” This monograph is the first in nearly a century to provide a detailed assessment of this important group of native forage fishes.
Structure and function of deepwater food webs—To promote restoration and conservation of functional Great Lakes food webs, I have created a new research theme through the Great Lakes Fishery Commission Fishery Research Program. The primary goal of the theme is to understand energy dynamics in Great Lakes food webs and the role of food web members in structuring resilient communities, and ecosystems. Towards this end, I am co-PI on a project to investigate trophic ecology and isotopic niche of humper Lake Trout from Lake Superior. I also recently completed a project on the patterns and processes of cisco trophic differentiation in relation to food web structuring using ecological tracers (isotopes and fatty acids). This body of research will help fishery managers to understand the implications of recent food web shifts in Lakes Huron and Michigan and provide a mechanistic understanding of what functional links need to be restored to promote healthy sustainable Great Lakes ecosystems.
Population dynamics and recruitment—To enhance understanding of population dynamics in a changing environment, I have completed studies on the trophic ecology, life history, and recruitment of Lake Whitefish (Coregonus clupeaformis), Lake Trout, and Coregonine ciscoes. I have also investigated the role of parental growth and physiological condition in relation to abiotic variables in lake whitefish recruitment. Results of the Lake Whitefish recruitment study are consistent with the hypothesis that energetic tradeoffs buffer the impacts associated with food web change and that extrinsic biotic variables, such as prey availability, may play a greater role in recruitment success for this important commercial species. The accuracy of age estimation methods continues to confound our understanding of population dynamics and undermines the validity of management for many fisheries. To address this problem, I have evaluated the accuracy and precision of age estimation methods and the potential impacts of error on dynamic rate estimates in Great Lakes lake whitefish. These studies led management agencies to shift emphasis from scales to otoliths for Lake Whitefish assessments, ultimately altering our view of population dynamics in this species.
Restoration of native fishes in the Laurentian Great Lakes—All of the research described above ultimately contributes to management decisions about maintaining healthy Great Lakes ecosystems. Habitat fragmentation by dams and barriers both hinders and facilitates the conflicting management objectives of restoring native species and controlling the spread of invasive species. Eroding dam infrastructure and increased societal desire to reconnect tributaries to their endpoint has created urgency among Great Lakes fishery managers to develop permanent solutions for passage of native fish species and the exclusion of non-native species at barriers. I have engaged fishery management agencies, the Army Corps of Engineers, and the city of Traverse City to design and implement bi-directional selective fish passage solutions for the Union Street Dam site on the Boardman River. This project is a ten year effort and is currently being funded by the Great Lakes Restoration Initiative (2016-2018) with the goal of providing solutions for one of the greatest fishery management issues facing the Great Lakes.
I place strong emphasis on science transfer – mobilizing science to empower resource managers. Achieving science transfer requires a broad network of colleagues and resource managers and superior communication skills to bridge the gaps between academia and resource management. As such, communications and science transfer are key components of my research program and are explicitly incorporated into each of my four primary research themes.