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White suckers gather to breed in the tea-stained waters of Wilsey Bay Creek.

Scientific Research in Michigan

  Do you want to partner with the Conservancy to do research on our preserves? If you are a professor or student at an academic institution and would like to help The Nature Conservancy discover answers to Conservation Science research questions, please fill out a research application.

McIntyre (right) and his uncle process longnose suckers caught in a net during preliminary research.

Major dams can block fish migrations that would otherwise fertilize the upstream reaches.

Suckers migrate up shallow streams like this one emptying into Lake Michigan during breeding season.

 

Migratory fish linking the Great Lakes and tributary stream ecosystems in the Upper Peninsula. This new project, sponsored by the Society for Conservation Biology’s Smith Fellows program, focuses on breeding migrations of fish as landscape-scale linkages between the Great Lakes and tributary streams. The inspiration for the work came from project leader Peter McIntyre’s observations of massive sucker runs during trips to the Upper Peninsula. This phenomenon struck a chord with McIntyre, whose doctoral work investigated the role of tropical fish in nutrient cycles and food webs of South American rivers and African great lakes. To assess the potential importance of sucker runs for the productivity of tea-stained streams in the UP, McIntyre teamed up with David Allan (University of Michigan), Patrick Doran (Director of Science for The Nature Conservancy in Michigan ), and Robin Abell (World Wildlife Fund). The Smith Fellows program, which provides post-doctoral funding for young environmental scientists to partner with academic and NGO mentors to address pressing conservation issues, offered an ideal mechanism for initiating the project.

Despite their humble name, suckers are the second most diverse family of freshwater fishes in North America (~76 known species) with multiple species found in most rivers and lakes in Michigan. Many sucker species undergo major breeding migrations in the spring, moving from lakes and large rivers into small tributary streams. Unlike Pacific salmon, suckers typically survive the breeding season and return year after year to spawn in streams. Sucker runs are likely a critical event in the annual cycle of streams because they temporarily increase fish biomass by orders of magnitude, inject new nutrients in the form of waste products and carcasses, and leave behind eggs and milt that carpet the substrate. The adult fish provide an important source of food for birds (osprey, eagles, herons) and mammals (black bears, otters). In addition, recent studies suggest sucker eggs and fry are a critical seasonal resource for salmonids and other gamefish. Though suckers often dominate total fish biomass and make spectacular breeding migrations throughout North America, their non-game status has discouraged research and management efforts.

Our team will quantify the number of suckers migrating into tributaries of Lakes Michigan and Superior, and evaluate the impact of these fish on stream productivity in the Upper Peninsula. Careful calculations of the amount of nutrients carried into and out of streams will be compared to direct measurements of nutrient dynamics and algal growth limitation in order to assess the ecosystem response to sucker runs. In addition, marking fish in each of a set of nearby streams will reveal whether fish return to the same stream every year, as observed in many salmonids.

The results from this study will provide critical input for the Conservancy’s efforts to protect the health of Michigan streams. Breeding migrations of fish are often blocked by dams and road culverts, particularly in the small streams where many sucker runs occur. In addition, migrating adult suckers are intensively harvested from some rivers for personal and commercial use. Research on the size and importance of sucker migrations will inform management of these native fish species as well as the Great Lakes ecosystems they inhabit. More generally, the project highlights the conservation value of protecting animal migrations that link multiple ecosystems. This lesson has been learned for mammals in Africa’s Serengeti grassland and salmon in the Pacific Northwest, and it may also be important here in Michigan.

Nature picture credits (top to bottom, left to right): Photo © Peter McIntyre (Wilsey Bay Creek); Photo © Peter McIntyre (white suckers). Photo © Jack Biek (sucker census); Photo © Peter McIntyre (dam).