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Moving Fish: Fishways Connect Habitats and Support Coastal Communities

By Sean McDermott, Greater Atlantic Region, Habitat Conservation Division

Have you ever seen a fish ladder or a fish lift? Do you know how one works? For many people the answer to both is “no.” If you live along the coast or on a river, there may even be a fish ladder or lift near you. Why do fish need these devices?

A fish lift is designed to move fish over tall dams with minimal effort by the fish. Fish are attracted to the entrance where they are crowded into a bucket called the “hopper.” The hopper is lifted and fish are released into a flume where they continue to swim upstream. Photo credit: Sean McDermott, NOAA

Migratory fish such as sea lamprey, rainbow smelt, American shad, alewife and blueback herring live and grow in the ocean and return to rivers to spawn. They arrive in coastal rivers every spring, with some rivers seeing millions of fish. After spawning, they return to the sea. Then, in the fall, millions of young fish make their way from river to sea. These fish become prey, or bait fish, supporting popular commercial and recreational fisheries. Stripers, Atlantic cod, and bluefish, to name a few, rely on these migratory fish for food. In addition, marine mammals also prey on these fish.

Fish Versus Dams: A Centuries-Old Battle

Sea-run migratory fish were an important food source for colonial settlers, and still are an important food source for some Native American tribes today. Rivers also provided travel routes, and hydro-mechanical power for development of agricultural and industrial technology. As technology developed, the construction of dams for navigation and hydro-mechanical power spread, blocking the migration of those sea-run fish. The conflict between dam-building industrialists and commercial fishers led to the “Shad Wars” from 1780 to the late 1800s, with warring parties shooting guns and cannons at each other and destroying weirs and dams, all in the pursuit of the best fishing spots.

 Pool and weir bypass is a series of small drops into pools of water. The drops are small enough for fish to swim over and pool controls the water’s energy, creating a suitable environment for fish to pass. The design can be used to go around a dam or up the face of the dam. Photo credit: Jack Terrill, NOAA.

In the end, dams rose and migratory fish populations fell, taking with them the economic and cultural traditions they once supported. Populations of several species are now at all-time lows. Three species (Atlantic salmon, Atlantic sturgeon, and shortnose sturgeon) are listed under the Endangered Species Act, and four others (rainbow smelt, alewife, blueback herring, and American eel) are either species of concern or have been petitioned for listing under the Act.

Thousands of Dams

Thousands of dams have been constructed in the Northeast since colonial times, from small farmer’s ponds and mill dams to large hydropower dams. Many dams are still in use for fire suppression, hydropower, water supply, and recreation. Many more dams no longer have a function. However, there is often local support for keeping dams in place to preserve historical structures, maintain recreational use, or simply for the scenic view. Where dams have a function or dam removal is not feasible, fishways are built to help migratory fish to get around dams and allow them to return to their spawning grounds.

Healthy Fish Runs Support Coastal Communities

NOAA Fisheries, through its Habitat Conservation and Habitat Restoration Divisions, works with hydropower developers, landowners, and municipalities, as well as state and federal agencies, to address fish passage needs in coastal rivers. This is a critical part of our agency mission to support coastal communities.

An Alaskan steeppass is typically designed for small dams. The ability to reduce energy within the chute allows the steeppass to be built at a higher angle. Photo credit: Sean McDermott, NOAA.

Healthy runs of migratory fish are not only good for the ecosystem, but they also support jobs for fish harvesters and provide funds—though licenses—for coastal communities. The harvested fish provide bait for lobstermen.  The harvest of elvers in Maine (American eel young of the year) can command a high price.  Bluefish and stripers chase migrating fish into rivers, providing sport for recreational fishermen, who in turn support local bait shops and outfitters. While at sea, many of these fish become prey for commercially important fisheries like cod, haddock, pollock, and flounders. Where dam removal is not likely to happen, fishways are important tools for supporting healthy runs of migratory fish.

What Do Fishways Look Like?

There are several different fishway designs. Each addresses a different fish passage problem; all have the same general function. The basic design includes an entrance, a chute, and an exit. Water volume, depth, and velocity are all critical to making a fishway work. Most important to how well a fishway works is the location. If not placed in the proper location, the fish will never use it. Examples of different kinds of fishways are on this page.

Get Involved!

For many smaller rivers, local advocacy groups and state agencies support local fishways by lining up volunteers to do annual migration counts and by raising awareness of the need to protect these fish and their habitats. Contact your local watershed association to find out how you can volunteer.

More Information

For more information about fishways and how they work, download our fish passage primer: