A Talk on the Wild Side.
Like many birds, some native fish are big-time travelers and they must migrate to complete their lifecycle — sometimes thousands of miles each year.
Fish migration depends on free-flowing connected waterways that allow fish to reproduce, feed and escape predators. This migration is not as easy to observe as flocks of birds making their way south, but it is just as critical to the long-term sustainability of the world’s fish and other aquatic species.
Migration success has been inhibited as more and more infrastructure was built to divert water for other priorities. Millions of dams and culverts have been built over the past 200 years, disrupting the flow of rivers and streams.
If these migratory waterways don’t support fish migration pathways critical for fish lifecycle needs, it could affect the ability for some species to survive.
Native species are part of America’s original heritage, ecologically important, neat to catch and good indicators of great water quality.
When fish populations decline because their migration is blocked, animals that share their habitat often struggle, too. That’s a big reason why the U.S. Fish and Wildlife Service and partners work to remove stream barriers and improve fish passage. Over the past 20 years the Service and more than 2,000 partners across America have been improving connectivity of waterways through fish passage projects that remove or modify barriers. The Service’s National Fish Passage Program has removed or bypassed 2,933 of the country’s estimated 6 million barriers, and reconnected more than 52,592 stream miles and 192,361 wetland acres.
These projects benefit people too, reducing flood risk, improving water quality and boosting access to fishing.
Connecting fish, rivers and people is the theme of World Fish Migration Day April 21; let's celebrate!
Four aquatic species helped by fish passage projects:
Photo by USFWS
Atlantic salmon, once found widely in coastal rivers of the Northeast, are migrating champs. After spending a few years in the rivers where they are born, the young head to sea. After one or more years at sea, the fish return to their home rivers to spawn. Because of overfishing, pollution and river damming, fewer than 1,000 adult salmon are now making the journey home each year. The species is on the edge of extinction with the last wild populations of this endangered fish in the United States in the Gulf of Maine.
In 2017, thanks to the work of the Service and many partners, 849 salmon were counted that made it past two dam removal sites along Maine’s Penobscot River.
Projects like those on the Penobscot River, where the river system is open once again to Atlantic salmon runs, shows promise for the species to recover.
Rio Grande Cutthroat Trout
Photo by Craig Springer
Once common in Colorado and New Mexico, this brightly colored native trout now occupies only about 10 percent of its historic habitat. Small, remnant populations are isolated because of water withdrawals for agriculture, and because many culverts are too small or set too high for fish to migrate.
The Service is helping to identify where better fish passage is needed, and then working with partners like Trout Unlimited and others in the Western Native Trout Initiative, as well as private landowners. Making good conservation even trickier is the fact that Rio Grande cutthroats don’t compete well with the aggressive non-native brown and brook trout that may also occupy their habitat. Biologists must balance improved stream connectivity against increased contact with rival species.
Photo by Jonathan Wardell/USFWS
Fish aren’t the only animals whose lives depend on stream connections. Freshwater mussels, the unsung champs of river filtration, can’t complete their strange lifecycles if their host fish can’t swim upstream, with mussel larvae attached.
Take the colorfully named Carolina heelsplitter. Loss of habitat, pollution and dams have all led to heelsplitter’s sharp decline.
This is the most endangered species in South Carolina. Orangeburg National Fish Hatchery in South Carolina is working with multiple federal, state and private partners to boost the heelsplitter population.
In 2015, when the hatchery first started breeding them, there were estimated to be only 154 individuals left in the wild
The Service and partners recently released 300 endangered mussels into Gills Creek in the Catawba River basin. Now comes the hard part: waiting four to six years for mussels to mature to learn if the effort succeeded. But just stocking rivers with mussels – or any species – is futile if you don’t reconnect waterways.
Topeka shiner Photo by Bruce Hallman/USFWS
It’s not just big fish that need good passage. In the prairie streams of the Midwest, including Iowa and southwest Minnesota, the tiny Topeka shiner is struggling to hang on.
What’s hammered the rare minnow, in part: diverting and channelizing streams. Some oxbows (bends in the river) have been disconnected due to poor agricultural practices that go back to the 1800s.Endangered Topeka shiners use the oxbows to spawn, rear their young and overwinter. Without easy passage between oxbows and the river, they can’t meet their seasonal needs.
Service biologists are working in Windom Wetland Management District in Minnesota, alongside private landowners to reconnect oxbows and streams. Clearing or modifying dams and reconnecting oxbows is the first phase. The second is replacing misplaced or mis-sized culverts.
Since the work began on shiners in 2010, Service staff has seen their numbers improve where oxbow connectivity has been restored.