River of the People, Part 2

In Part 1 of this post, we discussed American shad, but there are many other amazing fishes* (yes, fishes!) in the Delaware!

American eel have a particularly fascinating life history. They breed and hatch in the Sargasso Sea. The smallest life stage, the “leptocephali,” drift for about a year as they are transported by ocean currents toward North America. The next life stage, the “glass eel,” feeds little as they migrate actively across the continental shelf and into estuaries.

Elvers, the next life stage, begin to migrate back to the homes of their parents in freshwater rivers and streams.  Not only is the American eel a fascinating species, but eels provide important ecosystem services, have cultural importance for many cultures worldwide, and provide an important food source.

Academy Fisheries scientist Paul Overbeck hauls an American eel from the stream.

American eel are a host species of eastern elliptio mussels, which filter our water, are part of the food chain, and enhance in-stream habitat with their shells. The eels play an important role in transporting this sedentary species throughout our watershed.

Throughout history, American eel have been an important food source for the Lenape, and they are still important in our ecosystem by supporting other native fish and crayfish. Recently, Susquehanna River Basin Commission biologist Luke Wagner documented an eel weir created by Native Americans to catch out-migrating American eel.

The structure is still in place in the Susquehanna River (see the Youtube video here). Overfishing and exportation of glass eels, however, has been a significant threat to this species in recent years, and commercial weirs and harvesting are strictly regulated.

Atlantic sturgeon. Courtesy of NOAA

The Lenape also fished sturgeon, which could weigh up to 200 pounds or more and live up to 60 years! The sturgeon moon in mid-August marks the time that Native Americans in New York State harvested sturgeon. Sturgeon were mistaken for river monsters because of their incredible size, as was probably the case for the “Mosqueto” monster in Onondaga Lake in Syracuse, N.Y.

 Sturgeon are the producers of caviar, and the Delaware River had such a successful population of them that it became the largest supplier of caviar in the world, for a time. This unfortunately led to extreme overfishing of Atlantic sturgeon in the late 1800s to early 1900s and severe population decline.

Shortnose sturgeon, another species in our watershed, spend most of their time in the Delaware Estuary and are also endangered. The main threat  is fishery bycatch, or being accidentally caught by fishermen catching other fishes. As a result, there are many regulations to try to protect this species.

Measuring minnows as part of the research project

In the Delaware, efforts by the Delaware River Basin Commission in collaboration with Academy scientists Allison Stoklosa and David Keller have been studying how increasing the dissolved oxygen criterion for the Delaware Estuary can better protect sturgeon. These impressive fish also migrate between the river and the ocean and have unique, bony-plated scales that look more like Spanish roof tiles, aligned in rows (called scutes).

While our Atlantic and shortnose sturgeon are protected on the Endangered Species List, not all species of sturgeon are being protected. Typically, sturgeon take about eight years to reach sexual maturity, which means that caviar harvesting from fertile females is not a very sustainable practice.

“Globally, there is no telling how many species of sturgeon have gone extinct in the past hundred years. Nor is there any certainty, exactly, as to how many species remain,” writes Richard Adams Carey in The Philosopher Fish: Sturgeon, Caviar, and the Geography of Desire. Some brands of caviar are sustainably farmed, although there are other ethical issues around the practice.

If you are going to eat caviar, please check its source, and you can use this Seafood Watch Consumer Guide for other fishes. Supporting sustainable fisheries is one way small actions can spark big changes, which we at the Academy of Natural Sciences are very into!

American eels in a bright bucket

When Europeans arrived in the Americas, they saw an abundance of resources and assumed they were limitless. They failed to see that management by the Lenape and other tribes was a major influence on the sustainability of these systems. This “manifest destiny” mentality led to the overexploitation of forests and fisheries over hundreds of years. It is still causing stress for commercial fisheries and local fish communities.

Thankfully today we are coming to better understand that we must steward this land to protect it for all. Although many people still need to be convinced, there are so many people and organizations working to preserve our shared natural heritage. Researchers in the Academy’s Patrick Center for Environmental Research, many non-profit partners, legal experts like PennFuture and the Delaware Riverkeeper, and many others fight every day to understand the threats to our waterways, provide evidence for their need for protection, and push for decision-makers to implement policies that benefit the environment.

Programs like the Delaware River Watershed Initiative and many county, state and federal programs bring stakeholders together in preserving the aquatic ecosystems around us. With the Academy as the scientific lead for the DRWI, Stefanie Kroll and Academy scientists consider how better land stewardship can lead to improved water quality and the recovery of aquatic communities.

Carla Messinger, author and Lenni Lenape tribe member

In terms of everyday life around the river in the past and present, Carla Messinger’s description of “When the Shadbush Blooms” rings true: “Through the cycle of the seasons, what is important has remained: being with family, knowing when berries are ripe for picking, listening to stories in a warm home. Then and now are not so very different when the Shadbush blooms.”

*Fishes is the correct term for many different species of fish; fish as a plural refers to multiple individuals of the same species. Who knew?!

By Stefanie Kroll, Academy watershed ecology section Leader and scientific lead for the Delaware River Watershed Initiative; Carla Messinger, children’s book author and Lenni Lenape tribe member; and Allison Stoklosa, Academy fisheries scientist.

This post is the fourth in our 2020 series celebrating the Delaware River as River of the Year. Look for more installments to come. For previous, visit:

River of People, Part 1

Data and the Delaware

How Do You Manage a River?


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