Secret lives of fish

April 21 is World Fish Migration Day, a day to celebrate the importance of healthy, open rivers and the migratory fish that rely on them.

Many fish are mighty migrators!  Every spring and fall, millions of fish around the world are migrating between the oceans and our coastal rivers to produce new generations of fish. Millions more live in freshwater all year and are also on the move, some swimming 2,000 miles to spawn, feed and grow.

American shad caught on the Potomac River, Virginia. Credit_ Michael Bailey

Eastern brook trout adults travel to find spawning habitat in fall, and often migrate upstream to find cooler waters in summer.

Along the way, migratory fish encounter multiple obstacles such as dams and culverts, which prevent them from migrating out to the ocean or migrating back upstream to spawn and reproduce. And this has contributed to a decline in fish populations worldwide. World Fish Migration Day is an opportunity to raise awareness on these issues, and share resources for restoring fish passage. Through our national fish habitat partnerships, and with States, Tribes, watershed associations and many private landowners, the Service works to remove or modify these obstacles so fish can move freely.

Since 2009, the Service and partners have removed or replaced more than 507 barriers to fish passage from Maine to West Virginia, reconnecting more than 4,020 miles of rivers and streams and 19,300 acres of wetlands.

Many of the fish species that benefit are anadromous, meaning they were born in freshwater, migrate out to the sea as young juveniles and then return to freshwater to spawn. Much of their lives are spent in the ocean, where they may be a valuable commercial fish, or become food for other commercial fish. Resident freshwater fishes, such as brook trout, lake sturgeon and the American paddlefish, also benefit from improved fish passage. And fish are not the only winners. Every mile of river restored contributes more than $500,000 in social and economic benefits to people and communities. Additionally, removing dams to increase fish passage helps protect communities from flooding and enhances recreational opportunities for paddlers. Learn more about some of this inspiring work here.

Lake Champlain’s landlocked Atlantic salmon returned to the Boquet River to spawn. (Biologist Zach Eisenhower holding fish.)

You can help and have fun, too, with this Flat Fish Migration Activity. Show your support for World Fish Migration Day and keep rivers healthy and flowing free. Find an event near you at WFMD!

The American eel: Tale of a champion migrator

The American eel spawns and hatches in the ocean waters of the Sargasso Sea, near Bermuda, about 2 million square miles of warm water in the North Atlantic.

Map of Sargasso Sea in relation to NYS, USFWS

The larvae of this snake-like fish drift with the currents for about a year to find homes throughout their huge range, from Greenland to Venezuela. Many eels migrate north and make it all the way to Lake Ontario.

A champion migrator if I’ve ever seen one.

Eels go through a very complicated maturation process that usually takes them from oceanic waters to freshwater and then back to the ocean for spawning. Some eels remain in saltwater or estuaries like the Chesapeake Bay their entire lives.

If you need a reason to conserve these amazing marathon swimmers, then here are some pretty unique behaviors to keep in mind. Eels can absorb oxygen through their skin and gills, allowing them to travel over land, particularly wet grass or mud (so cool!). Eels also can cover their entire bodies with a mucous layer, making them nearly impossible to capture by hand.

Historically, eels were abundant in Lake Ontario with over 1 million documented annually migrating upstream at the Moses-Saunders Hydropower Dam on the St. Lawrence River. In 2001, there was a huge drop to 944 migrants. Numbers have increased in the last decade, but are still below 50,000, leaving biologists looking for answers.

The extreme population decline may have been fueled by the 1970s demand for yellow and silver life stages of the American eel. Harvest can be especially detrimental because of the eel’s slow and complex maturation process, but the definite cause of the decline is still not clear.

American eels no longer have access to much of their historical habitat because dams and other obstructions in rivers block their migration and prevent them from accessing all available habitat. Localized population declines are also attributed to mortality in hydropower plant turbines, degradation of current habitat, and overharvest.

Addressing these threats to the American eel and its conservation is a multifaceted approach which includes research and monitoring to increase eel access to former habitat and understand the mysterious spawning migration, as well as reducing anthropogenic mortality.

Organizations including the U.S. Fish and Wildlife Service, Canadian Department of Fisheries and Oceans, New York State Department of Conservation, the Ontario Ministry of Natural Resources and Forests, the Quebec Ministry of Forests, Wildlife, and Parks, the New York Power Authority, Hydro Quebec, and Ontario Power Generation have targeted projects to develop methods to safely pass eel around hydro dams on large rivers.

Within New York State, our field office has partnered to track eel migration in the St. Lawrence River. Eels are tagged with acoustic tags in the Bay of Quinte (on the north shore of Lake Ontario). They then travel downstream along the St. Lawrence River and can be tracked with receivers located at the Iroquois Dam, about 80 miles downriver. That migration usually takes place in late summer or early fall when the eels are maturing from their yellow form to a beautifully elegant silver mature stage.

Documented eel movements at the Iroquois Dam in NYS, USFWS

In collaboration with other natural resource agencies, the Service continues to work to mitigate adverse impacts to eels. These measures are specified during the licensing or relicensing of hydropower projects by the Federal Energy Regulatory Commision and can include the addition of facilities like eel ladders to safely pass eels upstream, screens to keep eels out of turbines, passageways to guide them downstream, or shutting turbines down at night when silver eels migrate.

Service biologists collecting eel receivers on the St. Lawrence River, USFWS

Eel ladders, which are designed specifically for this species, allow eels to swim over barriers using an ascending ramp. Eel migration is monitored at various areas both upstream and downstream to help understand and optimize eel passage inland and to the ocean.

Other conservation actions include restrictions on eel harvest by the United States and by the federal and provincial governments in Canada.

The U.S. Fish and Wildlife Service continues to work with partners to better understand and conserve this remarkable species. The more informed we can be about the species around us, the better we are able to makes conscious choices to conserve and protect wildlife and the ecosystems in which we all live.

 

Wednesday Wisdom – Norman Maclean

Original image by Lia McLaughlin/USFWS

World Fish Migration Day is Saturday, May 21.  A day for creating awareness on the importance of migratory fish and keeping rivers open so fish can move freely from place to place.

What better way for #WednesdayWisdom to celebrate than with a glorious image from the Pawcatuck River right above the White Rock Dam on the border of Stonington, Conn. and Westerly, R.I.; the dam has since been removed by the U.S. Fish and Wildlife Service – in partnership with the Nature Conservancy and others – to enhance fish passage benefiting river herring, American shad, and American eel.  This Hurricane Sandy-funded dam removal project helps reduce the risk of flooding from future storms and significantly increases benefits to commercial and sport fishing.

Speaking of fishing:  Known for his book  A River Runs Through it and Other Stories, author and scholar Norman Maclean knew the metaphor of fly-fishing and salvation, and his stories reflect how nature and the beauty of the river becomes a sanctuary for renewal and connects family and community in a deep and abiding way.  We can only imagine his thoughts on restoring river connectivity and letting the rivers run free for the fish that spawn and migrate to and from there.

Check out this cool fish migration video!

Resources for World Fish Migration Day! #wfmd

• Flat fish migration activity
• Fun Fish Facts
• Download a poster

More on the White Rock Dam removal project and all Building a Stronger Coast projects!

See all our Wednesday Wisdom blog posts!