Bringing back American eels in the Susquehanna River

Elvers climbing to base of Conowingo Dam on the Susquehanna River. Elvers are juvenile eels that migrate to brackish waters and begin to develop gray to greenish-brown pigmentation.
In today’s post, Sheila Eyler, fishery biologist and Project Leader for the Mid-Atlantic Fish and Wildlife Coordination Office, shares her success in working with American eel populations on the Susquehanna River.

In today’s post, Sheila Eyler, project leader for the Mid-Atlantic Fish and Wildlife Coordination Office, shares her success in working with American eel populations on the Susquehanna River.

When deciding to attend graduate school, I must admit that the American eel was not on the top of my list of fish to study. However, an opportunity to evaluate the impacts of hydroelectric dams on eel migration helped make the decision for me.

Seven years later, what I have learned about this unique and often misunderstood “snakelike” fish species has made me one of its biggest fans.

Historically, eels were abundant in estuaries and freshwater tributaries in much of the eastern U.S. and Canada. The construction of dams changed all this, drastically limiting eel migration routes from the ocean to upstream freshwater areas.

As a fisheries biologist, I continually look at the impacts that a species’ decline has on an entire ecosystem. In the case of the American eel, the population decline has an important – and fascinating – connection to certain native freshwater mussel species. Larval mussels need to attach to the gills of a fish in order to complete their life cycle. Some mussel species specifically need American eels to survive.

Elvers climbing to base of Conowingo Dam on the Susquehanna River. Elvers are juvenile eels that migrate to brackish waters and begin to develop gray to greenish-brown pigmentation.

Elvers climbing to base of Conowingo Dam on the Susquehanna River. Elvers are juvenile eels that migrate to brackish waters and begin to develop gray to greenish-brown pigmentation. Credit: Maryland Fisheries Resources Office, USFWS

With fewer eels headed upstream, mussel larvae have fewer hosts to help them survive. In rivers where dams have excluded eels for decades or longer, some freshwater mussel populations have also declined. Fewer mussels means poorer water quality because mussels have the ability to filter gallons of water a day.

Working on the restoration program for American eels on the Susquehanna River is never dull and continues to bring daily adventures. Along with several partner agencies, my colleagues and I have been trapping young migrating eels at the Conowingo Dam and stocking them into the upper watershed for several years. In 2013, we collected nearly 300,000 elvers (baby eels) for the restoration program.

Stocking eels has been very successful in the Susquehanna River. And to our delight, we are now finding eels with larval mussels attached to the gills, which will promote the growth of the mussel population.  

Watch American eels swim upriver

For me, it has been very rewarding to be part of this successful restoration program. I am proud to share the story of the American eel – an underappreciated resident of much of our freshwater streams with an amazing life cycle and connection to our environment.

For more information on the Susquehanna River American eel stocking program, read more at:

9 Comments on “Bringing back American eels in the Susquehanna River

  1. First, is it not true that there is no direct evidence that large populations of mussels ever existed on the Susquehanna River? The only evidence you have is anecdotal evidence, correct? Isn’t also true that in order to restore these eels the fish and wildlife service is forcing the owners of the four dams to spend hundreds of millions of dollars to build fish passage for these eels and those costs are being passed on directly through higher electric rates to residents of Pennsylvania and Maryland who depend on hydropower for their electricity needs?

  2. In addition to the increased utility costs your agency’s actions are costing Marylander’s and Pennsylvanian’s, I am curious how much money is being spent on Federal employees salary and travel to bring eels back to the Susquehanna. Don’t you think the American taxpayers, who pay the brunt of all these costs, have a right to see those facts in your blog as well? There’s no commercial fishery for these eels, correct? There’s no recreational fishery for them, right? So there only real value is they act as a host for mussle glochidia. Mussels you can’t even prove ever existed in any large numbers on the Susquehanna.

    • Thanks for your comment and interest. Our agency is dedicated to our mission of conserving fisheries for the ultimate benefit of the American people. Science does show that freshwater mussels were once common in the Susquehanna River and remain common in many other east coast waters. Research studies by U.S. Geological Survey find 2 million eastern elliptio mussels per river mile in the Delaware River, which runs alongside the Susquehanna, and find the species is equally abundant in the Potomac River. Actually, elliptios make up 99 percent of mussels in our streams (technically 99 percent of the mussel biomass).

      However, along the Susquehanna River, above the dams on the main stem, we find only pockets of older elliptios that have likely survived from before the dams were built. We also find that there is no recruitment of juvenile elliptios, which, as you mentioned, we expect is connected to the lack of American eels upriver of these dams. Before the dams were built, there was a strong eel fishery in Pennsylvania, with up to a million pounds of eel harvested per year, and the commercial fishery for eels continues in other areas along the eastern seaboard. Providing eel passage at the Conowingo Dam is the best management option we have to conserve American eels by allowing passage to upstream breeding areas, and the cost of installing eel passage is nominal.

      We will soon be surveying for elliptio mussels in these areas, as for five years we have physically moved eels upriver to provide hosts for these mussels. We believe we will see positive results of this work, as we’ve picked up eels with elliptio glochidia (mussel larvae).

      • You are avoiding the question. Telling readers that you’ve made great progress moving eels up river isn’t what I asked about. Stop trying to spin it to make your agency sound better. So let’s begin with your first deception. Science does not show definitely that Elliptio complanata was once abundant in the Susquehanna. If it does, cite the study. Let’s look at that USGS research you memtion. William Lellis, who heads the USGS Northern Appalachian Research Lab in Wellsboro, PA had been looking at mussels on a 125 mile stretch of the Delaware river and then you mention the mussels are also abundant on the Potomac. There you go trying decieve people again. Did I ask about the Delaware or the Potomac? Nope! So why are you telling me about them? I’ll tell you why. Because I am right. There is no evidence showing mussels were historically in the Susquehanna in any real abundance. In fact, Mr. Lellis, USGS’ lead researcher, has said concerning the Susquehanna, “mile after mile of nothing when it comes to mussels.” Now before you go and tell me that’s because of those 4 dams and the lack of eels, my challenge to you is for you to cite one peer-reviewed publication that shows beyond a doubt that mussels were ever present on the Susquehanna in any real abundance. I’ll save you the time. You can’t. Such evidence doesn’t exist. Your agency is using evidence of lots of mussels on the Delaware and making a leap of faith to say if they were on the Delaware then they must have been on the Susquehanna and that’s simply really bad science. Worse yet, you’re using that faulty assumption to jusify spending hundreds of thousands of taxpayers dollars on eels because the eels are good for mussels. It’s a Government run Ponzi scheme. Add to that the fact you are forcing the owners of those four hydropower dams on the Susquehanna to spend hundreds of millions of dollars on fish passage that they then pass directly on to Marylanders and Pennsylvanians in the form of higher electric rates. And none of the decisions based on real data or good science. Can you say wasted money? If you can disprove me, please do. Cite any real evidence that show mussels ever existed in any abundance on the Susquehanna. Tell the readers of the blog how much the Government estimates the fish passage you are mandating on both sides of the Conowingo dam will cost. Tell the readers how much fish and wildlife is spending on eels annually.

  3. I have never seen a blog where you submit your comments and it takes 15 hours to have them show up! Does that message you get “your comment is awaiting moderation” mean the Government has to read and approve the comment first? Is Big Brother watching? Because if that’s the case, that sure seems like censorship of the public by the Government on a taxpayer funded website. So, if I don’t see my comments in a few more hours, I’ll just spend my day writing letters to the editor to a whole bunch of PA and MD newspapers asking my questions, citing the blog, and noting the censorship by Government officials.

  4. Hey Govt. watchdog……I just happen to be one of those people who would like to see the american eel brought back to the upper susquehanna(they taste delicious by the way). We have people who remember catching eels in the 1960’s in Bradford county,sadly those days are long gone. And what you and a whole lot of others are forgetting and what science has actually proven is that hydro-electric dams cause more damage to the eco system by preventing migration. Ask yourself where the American Shad went to??? Dams went in and eel and shad and mussel populations plummeted,direct correlation all responsible to that fact alone. Your want of cheap electricity shouldn’t come at the loss of our fishing habitat,glad to see they are trying to fix it.

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