Fish species that are poor jumpers are directly limited or impacted by physical barriers in rivers. Many of Michigan's native species - suckers, pike, walleye, sturgeon, even burbot from the depths of our Great Lakes, as examples - are terrible jumpers YET perfect examples of species that connect Great Lakes, lakes, rivers and streams. Pike travel long distances up rivers seeking wetland spawning, (reproduction) and nursery areas; as do most species of suckers. In fact, suckers represent a large number (and biomass) of fish migrating up rivers to spawn. They don’t die after spawning (returning to lakes) but many do (relating to old age or stress of spawning). Decaying adult fish, fish spawn/eggs, and newly hatched/juvenile fish play an important role of returning nutrients from lakes far upstream into the upper stretches of the watershed - UNLESS they are disconnected. This story - and as Dr. Scribner describes - is often told about the great migration stories of Pacific Salmon out west - but not as often about Great Lakes suckers, which may deserve the same credit for their important ecosystem role.

Quite simply dams - by design - disconnect rivers (resulting in many jokes about what a fish swimming up river says when it runs into a wall). The impoundments or reservoirs created behind dams change habitat (changing river habitat to lake-like habitat) by slowing and holding water. This causes water to warm, which increases river temperatures down stream (impacting coldwater fishes, like trout, often inhabiting coldwater river habitats).

RESOURCE: Dams regulated by the State of Michigan

RESOURCE: Explore dam safety in Michigan in the resources developed by the Association of State Dam Safety Officials

RESOURCE: Find out more information about the status of (some) dams in your county in the National Inventory of Dams Interactive Map.

However, dams serve many purposes for humans including hydroelectric power (roughly around 1-2% of Michigan's total energy production currently). This map illustrates (in red) the area of river or watershed habitat inaccessible to migrating Great Lakes fishes. Is the trade-off worth it?

Are there compromises or potential solutions to remedy the problem. Fish Ladders, perhaps?

People like to travel - and whether by foot, horse, or car we also find ourselves crossing rivers. Bridges make these river crossings easier (and safer) but can come at the expense of aquatic organisms and river ecosystem function DEPENDING on how the crossing is designed.

(Sounds like another great engineering exploration for students!)

Matching velocity of the river with the road crossing structure is key - too much flow OR too little can effectively cut off passage for aquatic life. Insert here the story of Goldilocks and the Three Bears.

• Too LITTLE - the underpass can dry up during seasonal low flow summer conditions (and aquatic organisms like water)

• Too MUCH - think about 'thumb over end of garden hose' which increases velocity of water (through constricted space) and results in erosion and scouring around structure - over time you get 'lipping' or mini-water falls on downstream side of culverts (and many fish and aquatic organisms - while they can swim fast - are not good jumpers)

Alpena High School's "Science in the Sanctuary" class worked with conservation organization Huron Pines to learn how replacing road-stream crossings can improve the connectivity of different bodies of water.

PBSE EFFORT ALERT: Students used their science communication skills to create this River Restoration website and a fun TikTok page to share what they had learned about culvert replacement in partnership with Huron Pines.

RESOURCE: WBKB TV 11 'Students teach on Tik Tok' local news story

PBSE EFFORT ALERT: Students studied water quality on the Trout River in connection with their Salmon in the Classroom project, collecting both biotic and abiotic water quality data at the river site where they release their fish. Working with community partners, such as the Presque Isle County Conservation District and the Presque Isle County Drain Commissioner, the students were able to both learn from local experts while also providing partners with valuable information. No water quality monitoring had previously been conducted on the Trout River, Rogers City middle school science students were able to collect important new data of great value to their community partners.

RESOURCE: Learn more about this PBSE project in action