Tag Archives: fish migration

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.

EelMapIWCD2 (1)

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.


Fish, rivers and people: Making the connection

May 21, 2016 is World Fish Migration Day (WFMD) and you are invited to take part and help make an aquatic connection.  The Service, along with thousands of other organizations around the world, is celebrating this one day global-local event to create awareness of the importance of open waters for migrating fish.

This Atlantic salmon pre-smolt will swim to sea for a few years before trying migrate back up stream to spawn. Photo credit: Peter Steenstra/ USFWS

This Atlantic salmon pre-smolt will swim to sea for a few years before trying to migrate back up stream to spawn. Photo credit: Peter Steenstra/ USFWS

Most people do not actually see fish migrate the way we see birds or other land animals migrate. But in fact, many species of fish migrate thousands of miles every year in order to reach feeding and spawning habitats critical for survival. And this is where “connection” makes all the difference.

The Flock Process Dam Removal project in Norwalk, Connecticut removes the first dam on the Norwalk River, eliminating dam failure risk, allowing fish to move freely between salt and freshwater, facilitating sediment transport and building natural defenses in both upstream and downstream areas of the river to future flooding. Approximately 3.5 miles of stream access are being restored.

The Flock Process Dam in Norwalk, Connecticut was removed to help fish move freely between salt and freshwater.  Approximately 3.5 miles of stream access was restored when this dam was demolished. Photo credit: Lia McLaughlin/USFWS

Historically, waterways from oceans to rivers, streams, ponds and lakes were free flowing migratory routes that fish travelled to feed, nest and spawn. But over time, these aquatic byways became blocked with dams, roads, inefficient culverts and pollution, which hindered the ability of fish to complete their life cycles and caused declines in populations.

Opening up fish passage ways will improve recreational fishing opportunities throughout the country. Photo credit: USFWS

Opening up fish passage ways will improve recreational fishing opportunities throughout the country. Photo credit: USFWS

So what’s the big deal? Why should I be concerned about fish populations?  Migratory fish provide many benefits to people and wildlife: They are a critical food source, they are indicators of the health our waters, they provide outdoor recreation opportunities, and help boost economies around the globe.

A young angler in Massachusetts participates in the Flat Fish Migration activity while at a fishing derby. Photo credit: USFWS

A young angler in Massachusetts participates in the Flat Fish Migration activity while at a fishing derby. Photo credit: USFWS

Bring on World Fish Migration Day (WFMD), and the opportunity for you to support fish conservation in your own backyard.  By working together we can increase awareness, share ideas and make commitments to take action for a better aquatic world for everyone.

Copy of AllDressedUpLeading up to WFMD, check out the useful resources on the websites to learn, help educate others and make a plan for your action. Many organizations throughout the U.S., including here in the Northeast, are planning events leading up to, and the day of WFMD.  Participation is sure to be fun, educational and satisfying.  Together we can make a difference in helping many migratory fish species recover and even thrive!


Resources for World Fish Migration Day!