The Science Behind Selective Fish Passage

by Daniel Zielinski, GLFC Principal Engineer/Scientist

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

communities? These are among the questions the FishPass Science Team is tackling and that I discuss below.

The challenge of selective fish passage is fundamentally sorting an assortment of things. Sorting a stream of objects with variable attributes is not unique to fish passage. Attribute-based sorting technologies have been successfully developed in other industries, such as material recycling. The Great Lakes Fishery Commission (www.glfc.org), a binational treaty organization and FishPass lead, has for 50 years invested in the development of several technologies, such as traps, behavioral guidance (e.g., migratory pheromones – substances produced by sea lamprey that attract other adult sea lamprey), and deterrence (e.g., biological alarm cues – substances released by injured or dead sea lamprey that deter other sea lamprey) in their pursuit of invasive sea lamprey control. Other attribute-based sorting technologies like screens, computer-based image recognition, and hydraulic challenges have been developed and used in various fish passage scenarios worldwide.

Drawing inspiration from the recycling industry, the FishPass Science Team is for the first time integrating various attribute-based sorting technologies in a realworld scenario to optimize fish sorting and ultimately to re-establish ecological connectivity between Lake Michigan, Grand Traverse Bay, and the Boardman/Ottaway River. One of the team’s first challenges is determining the order of sorting operations, where many potential configurations exist with even a small number of techniques and technologies (e.g., three sorting tools can be configured in 32 different ways). Following the example of the recycling industry, where the material is sorted first by size, a fish sorting process could target readily sortable attributes, like size, first, followed by more variable features, such as the location in the water column animals swim or responses to environmental stimuli. Like the recycling industry, redundancy will be built in because we do not anticipate each sorting tool to be 100% effective for 100% of the animals that encounter it. In this way, a fish will experience the same sorting apparatus multiple times on its journey upstream. The end goal is to consecutively and iteratively refine the assemblage of fish as they move through the fish passageway, removing undesirable species along the way and having a clean collection of desirable fishes as they reach the upstream end of the facility for controlled, volitional movement above the barrier.

At our disposal are sorting tools that range in complexity from the surprisingly low-tech bar screen, which only permits passage to fish narrower than the bar spacing, all the way up to technologically advanced recognition systems, which use computer learning to identify species from a video or still image rapidly. Ongoing research inside the U.S. Geological Survey’s S.O. Conte Anadromous Fish Laboratory is seeking novel ways to sort sea lamprey from native fish, like white sucker Catostomus commersonii, based on their ability to overcome fast and turbulent water flows. By applying a thin honeycomblike material to the sides of a laboratory flume, sea lamprey are prevented from using their suctorial mouth to attach and rest (a behavior critical to their ability to move upstream against flow), making them less likely than other native fish to overcome fastflowing water during their upstream migration.

The sea lamprey’s ability to attach to river substrate, like cobbles, is unique among Great Lakes fishes and has inspired research at Michigan State University, where flexible, pressuresensing smart panels are being developed to detect when a sea lamprey attaches and possibly trigger ensuing mechanisms, such as closing a gate or opening a trap. FishPass researchers are also developing an optical sorting tool that combines technologies developed nearly 3,000 years apart. First, an Archimedes screw, a technology first described in 234 BC, lifts fish out of the water and sends them down a wetted ramp where multiple highresolution images are taken (see photo). A computer analyzes, in real-time, the images and identifies the fish as desirable or not, thereby initiating passage or removal options for that individual. Initial tests have shown such a system can correctly identify a sea lamprey with over 99% accuracy.

Experimental design of the fish sorting processes has not yet been established. However, one can envision a sequence that uses screens or high flows, attachment inhibiting surfaces, and traps to iteratively remove sea lampreys or other undesirable species from an upstream moving fish assemblage. The termination of this sorting process could be an optical sorting tool to perform a final check or quality control on all fish being passed and remove any residuals that made it above the sorting gauntlet. Informed by theory, data, quantitative models, and expert opinion, the FishPass Science Team is currently working to determine the initial selection of tools and their configuration to be armed when FishPass opens for research.

Evaluation and improvements to the sorting processes at FishPass will follow an adaptive management approach, an intentional scientific approach to making management decisions and adjustments in response to new information and changes in context. Management agencies regularly use adaptive management to conserve and manage aquatic species and habitats. At FishPass, this approach will play out through annual surveys of the local fish community, active monitoring of fish behavior and movement up to and through the sorting processes, and making informed adjustments to the sorting tools or configuration iteratively. Adjustments will happen both within and between migratory seasons using an automated data carriage to collect environmental data and a mobile gantry crane to make in-season adjustments to channel and equipment configuration rapidly.

The sorting processes will be evaluated individually and collectively to see what proportion of available desirable and undesirable species are blocked or removed versus bypassing a sorting challenge. A portion of fish moving through FishPass will be implanted with miniature Passive Integrated Transponder (PIT) tags, similar to pet microchips, and their movements will be tracked as they pass through a network of 20+ antennas. Paired with automated video surveillance to monitor fish leaping attempts at all barrier structures, scientists will have finescale movement data to evaluate when, where, and how fish interact with blocking or sorting technologies. A multitude of sensors will also be used to measure water velocity, turbulence, sound, light levels, and many more environmental cues that