Michigan Trout Unlimited
MICHIGAN Trout
The Science Behind Selective Fish Passage
10
by Daniel Zielinski, GLFC Principal Engineer/Scientist
Spring 2022
Standing on the bank, waders on, flyrod in hand, the emerging sun gently begins to lift the fog off the water and slide it downstream. My mind drifts as I recall accounts by early Great Lakes natural historians of the majestic forests and rivers teeming with lake-run fish. I drain my coffee and consider what the day will bring. While Michigan’s streams and rivers continue to provide wild places for fish and animals and remarkable spaces for people to experience the wild, like much of the nation, our waterways and habitats have been dramatically altered during the past century―they are not the same banks that George Griffith once stood on over 60 years ago when Trout Unlimited was founded. Dams and barriers are among the greatest human changes influencing our waterways. While barriers provide many valuable ecosystem services, such as hydropower, many are now legacy of past industrialization and continue to restrict native species movements, disrupt life cycles, and potentially limit fishery production. Fast forward to today, and across our nation, barriers are being removed to restore rivers to a more natural state. However, in the Great Lakes, invasive species have changed the game because connectivity between rivers and their lakes can have consequences for both desirable and undesirable species that affect ecological and human economic activity in unintentional ways—the so-called connectivity conundrum. In watersheds that face the risk of invasion by non-native species or harmful effects of co-occurring species on endangered populations, the connectivity conundrum refers to a global tension between improving passage across barriers for desirable species (i.e., connecting habitats throughout the watershed) while eliminating passage by invasive or undesirable species. Here in Michigan, the connectivity conundrum is playing out on the Boardman/Ottaway River, where a novel science-based solution, FishPass, is being developed to address the conundrum. The Boardman/Ottaway River drains 287 square miles of Grand Traverse and Kalkaska counties in Northwestern Lower Michigan. It encompasses 180 miles of perennial streams and 74 natural lakes emptying into the west arm of Grand Traverse Bay in Traverse City, Michigan – traditional lands of the Aanishinaabe from the Grand Traverse Band of Ottawa and Chippewa Indians. Led by the Boardman River Restoration Project’s Settlement Agreement Implementation Team (IT), three upstream barriers, Brown Bridge (in 2012), Boardman (2018), and Sabin (2019) dams were removed, and a natural river channel was restored. A proposed modification of the last downstream barrier, Union Street Dam, to accommodate native fish passage and invasive species control, FishPass (www.glfc.org/fishpass.php) will complete one of the largest whole-river restoration projects in the nation. FishPass is the capstone of a nearly 20-year restoration project on the Boardman/Ottaway River to reconnect the river
with Lake Michigan for the first time in almost 150 years. FishPass will replace the deteriorating Union Street Dam with a new, complete barrier to all fish that will provide the ability to sort and selectively pass desirable fishes while blocking harmful invaders like the sea lamprey Petromyzon marinus (shown above), which can kill up to 40 pounds of Great Lakes fishes in its adult parasitic life stage. An international team of more than 50 fishery managers, biologists, ecologists, and engineers worked for four years to design FishPass. On the cusp of construction, this team has turned its attention to one of the project’s significant challenges: research to develop controlled sorting of native and non-native species. A sorting solution does not exist in the natural sciences. Therefore, the team has looked to other industries for inspiration. FishPass research will encompass two primary elements: (1) developing safe, effective, selective passage solutions; and (2) understanding the ecological effects of fish passage on ecosystems. Sorting Species for Selective Passage The first element of the research will occur below a complete barrier to all fish movement. The research will involve matching sorting technologies and techniques to attributes of fishes to maximize connectivity while minimizing the risk of invasive species passage. Developing a novel approach to sorting species for selective passage of fishes is complicated in several ways. At a minimum, 36 species of fish co-occur with invasive sea lamprey (the primary target for removal) during their spring spawning migrations into the lower Boardman/Ottaway River. These species differ in the timing or phenology of river use; some species undertake winter and others spring spawning migrations from Lake Michigan, while others may show opportunistic feeding forays between the lake and river. Fishes also differ in their morphology, or size and shape, their physiology, such as the ability to swim in currents or jump over obstacles, and perhaps most challenging in the context of sorting, fishes display a large diversity of behaviors. Further complicating sorting is that each attribute, especially behavior, can differ among individuals within a species. These challenges present opportunities. Many of the differences and similarities in characteristics among and within species can be quantified using available data and exploited for sorting. Boardman/Ottaway River fishes can be grouped into guilds based on similar phenological, morphological, physiological, and behavioral attributes, which can then be targeted for sorting as a group with specific tools. What tools? How will sorting work? How will we know if FishPass is successful? What happens when native fishes can swim upstream? How does restoring connectivity affect ecosystem function or growth of upstream fish
