Fishing for Evidence: River Weirs in Pennsylvania

Throughout time, rivers have played an essential role in the settlement patterns of Pennsylvania’s inhabitants. Rivers helped to define travel routes, provided fresh water, and were a bountiful source of food. Pennsylvania’s rivers have changed considerably since the arrival of Europeans in the 17^th and 18^th centuries due to floods and human impact, but evidence of past fishing activities is still apparent today in the form of stone river weirs often visible during periods of low water. River or fish weirs are stone structures made by Native Americans and European colonists to corral and trap fish. This blog will discuss the forms and distribution of these features in Eastern Pennsylvania’s rivers.

The existence of fish weirs or fish traps in Pennsylvania has received relatively little attention from archaeologists, and only 10 such sites have been formally recorded with the Pennsylvania Archaeological Site Survey files (P.A.S.S). Additional sites have been described in publications or identified but not yet recorded. A 1969 publication identified 36 fish traps in Maryland on the Potomac River between Point of Rocks, Maryland and Harpers Ferry, West Virginia (Strandberg and Tomlinson 1969:312). Preliminary data from a 2019 Fish Wier Recording Survey conducted by the North Carolina Office of State Archaeology identified 750 fish weirs from more than 10 states, including 141 in Pennsylvania. Following North Carolina, Pennsylvania has the second highest concentration of weirs identified in this survey.

Locations of 750 Fish Weirs Identified in the North Carolina Fish Weir Recording Project (Cranford 2019). 

Until recently, factors that impeded the identification of fish weirs were a lack of high-quality satellite imagery (or difficulty obtaining historic aerial imagery), difficulty identifying these features from the ground, a lack of associated artifacts, or a lack of interest from the archaeology community. With advancements in technology and increasing access to high-quality satellite imagery through Google Earth, however the reliable identification of fish weirs is now possible. By accessing multiple years’ satellite imagery, the weirs appear and disappear with the rise and fall of water levels. Due to environmental factors from climate change and ongoing threats from human activity, the need to record these structures is even more critical.

During a brief period of the year, a prominent fish weir is visible from the I-83 bridge in Harrisburg, PA, facing south. (image: Melanie Mayhew)

Along the Eastern Coast of the United States, weirs most frequently take the form of “V”-shaped or multiple “V” or “W”-shaped structures. Multiple-“V” shaped weirs had the advantage of being useful for capturing migratory fish on both their downstream and upstream journeys (Rogers 1993). The tips of the “V”-shaped weirs could be opened or closed depending on direction of the fish or eels’ travel. Pennsylvania’s Susquehanna and Delaware Rivers are habitat for migratory fish, such as shad, eel, and sturgeon. Populations of these fish have greatly diminished due to overfishing, pollution and in the case of the Lower Susquehanna River Valley, four large hydroelectric dams. Surveys have shown that “V” and multiple-“V” or “W”- shaped weirs on the East Coast extend from Georgia, through Pennsylvania and into New England. Additional historic period weirs also exist which may have been associated with canning factories or other historic fishing activities.

Establishing dates for stone weirs has proven to be difficult, even in areas where they have received attention from professional archaeologists. The traps or weirs located on the Potomac River by Strandberg and Tomlinson are attributed to pre-contact Native Americans or early colonial settlers. Moreover, several clusters of fish weirs in Pennsylvania are near pre-contact or contact period Native American village sites, further suggesting that these locations may have been used prior to the arrival of Europeans, although their continued use by early European settlers cannot be ruled out.

Fish weirs or traps are often located at natural rapids such as these on the Susquehanna River (image: Google Earth).

Recognizing cultural landscapes is an important line of research for archaeologists as we strive to improve our understanding of past cultural behavior. Discussions with indigenous peoples can provide additional lines of evidence that will add to our knowledge of how weirs were made and used. Examination of archaeological collections containing dietary fish remains recovered from within close proximity of these weirs improves our understanding of early diets. Modern technologies, such as satellite imagery and LiDAR are non-destructive options for gathering useful data. Recognizing and recording cultural landscapes is an important endeavor for archaeologists seeking to better understand and preserve the past.

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Additional Information about Fish Weirs:

Cranford, David

2019      A New View of Southeastern Stone Fish Weirs. Poster presented at the 2019 Southeastern Archaeological Conference, Jackson, Mississippi.

Lutins, Allen

1992      Prehistoric Fishweirs in Eastern North America. MA thesis, Department of Anthropology, State University of New York, Binghamton.

Rogers, Anne Frazer

1993      Fish Weirs as Part of the Cultural Landscape. Paper presented at the 1991 Appalachian Cultural Resources Workshop, Asheville, North Carolina.

Strandberg, Carl H. and RayTomlinson

1969      Photoarchaeological analysis of Potomac River fish traps. Am. Antiq. 34:212-219.

2021  Dozens of ancient eel weirs uncovered in Susquehanna. Bay Journal    

For more information, visit PAarchaeology.state.pa.us or the Hall of Anthropology and Archaeology at The State Museum of Pennsylvania .

For more information, visit PAarchaeology.state.pa.us or the Hall of Anthropology and Archaeology at The State Museum of Pennsylvania .