What the heck is the American Eel?

Freshwater eels are the only catadromous fishes in North America. Catadromous means that they spawn in salt water and live as adults in fresh water. Anadromous fishes, like salmon and American shad, spawn in fresh water but live as adults in the ocean. On this continent, eels are represented by a single species, the American eel (Anguilla rostrata). Although the eel looks snake-like, it is a fish.

The American eel is found along the Atlantic and Gulf coasts, where young eels swim far upstream into small tributaries. The Delaware River in Pennsylvania has the most abundant population of eels of all the state’s streams, because there are no dam obstructions to prevent the eels upriver migration. Eels are rarely found in the Susquehanna River system and are occasionally seen in the Potomac River watershed.

Protecting the American Eel

After declining to list the American Eel under the Endangered Species Act (ESA) in 2007, the US Fish and Wildlife Service (FWS) opened a 90-day comment period in late August 2011 soliciting scientific and other relevant information on whether federal protections for the eel are appropriate. Here at Lower Susquehanna RIVERKEEPER we know these critters once represented over 25% of the aquatic biomass in the Susquehanna River Watershed and had a historic range of thousands of square miles. Tragically, today they represent less than 1% of the biomass and have lost more than 85% of that historic habitat.

Where are the eels and why aren’t they present? Great question – we put together and submitted thorough technical comments to the FWS on that exact question. We firmly believe the American Eel deserves protection under the ESA in a significant portion of its historic habitat including the Susquehanna Watershed. Read our technical comments here on why we don’t see many eels in the Susquehanna and why they deserve strong protections.

Eel Ladder Experiment

Below are some pictures of Conowingo Dam’s $500 eel ladder experiment. Eel ladders help eels travel around dams which block their migration upriver.

Where are the Mussels?

Most of the “old-timers” remember when you couldn’t walk through the Susquehanna or small streams without stepping on mussels. We know that Eastern Elliptio mussels used to be EVERYWHERE! So where did they go?

So far we’ve observed that few Elliptios are still living in Codorus Creek, which is historically highly polluted. There are lots of Asiatic clams there, so we don’t think it’s competition either. Scientific studies show the loss of the larvae’s host species, like the American Eel, or possibly too much sediment. We’ve found old shells in the Conestoga, Conewago, Yellow Breeches, Swatara, and along the banks of the Susquehanna.

Please help us add to this research. Let us know if you are finding mussel shells in the streams near you. Take pictures and send them to us. We are looking for mussels (like the ones pictured in the photos under “Background” below,) not the little clams, which are an invasive from Asia.

Recent research from USGS’s Bill Lellis has led to a strong theory that the dams are blocking the eels, which are the host species for young mussels, which could be filtering much of the nutrient and sediment pollution that ends up in the Upper Chesapeake Bay. Unfortunately, mussels have declined dramatically since the dams were built. It could be that the Bay’s problems are significantly worsened by the lack of mussels. In the Delaware mussels filter the water 6 times before it hits the bay.

We have discussed this with staff from Senators Specter and Santorum, Congressmen Holden, Schuster, Gilchrest, Rupersberger and Platts, as well as DEP’s Cathy Myers and USGS staff. We’ve asked DEP if a pilot project of mussel reintroduction would be a good effort, and Dep. Secretary Myers suggested a Growing Greener project that incorporated Legacy Sediment remediation and mussel reintroduction. Plans are in the works to figure out how we can rstore this important species in the Lower Susquehanna. Please reply if you are interested.