With Hale leading the effort and aided by a DESG intern, Brandywine Shad 2020 started fishing, enlisting supporters, community members, and Simeon Hahn, an official at the National Oceanic and Atmospheric Administrations National Ocean Service, Office of Response and Restoration and a member of the Delaware Sea Grant Advisory Council. During their first trip on the river they caught a few adult shad, which was fantastic, but not proof of the newly opened section of creek serving as a juvenile nursery.
During the second sampling event, at the end of July, they caught more than 150 juvenile shad, demonstrating how important this habitat was to multiple life history stages of American Shad.
Once we found them, that was a big deal for the purpose of the project and for the purpose of the whole nonprofit, Brandywine Shad 2020, Hale said. Their whole mission is essentially reopening and rewilding that habitat corridor for diadromous fish like shad and river herring to essentially renaturalize flow and see some type of ecosystem balance restored.
Hale said since that exciting first catch, they have consistently caught shad, both adults and juveniles, in the follow-up seining as well. (A seine net is made to hang vertically in the water with weights at the lower edge and floats at the top.) It doesnt prove shad are spawning in the newly open section of creek, although it is likely and Hale plans to return to conduct a spawning survey in the future. But this years catch does show at a minimum that juvenile and adult American Shad are using the habitat newly available to them.
Bigger than Fish
Kauffman said the discovery of juvenile shad in the section of Brandywine Creek previously between the first and second dams was a big discovery, historic for the waterway. And Hale notes there is the potential for 10 years or more of ongoing research to understand how the shad population is affected, as initial fish reach spawning age and as more dams are removed or have fish passages installed if they cant be taken down.
But from his perspective at the Water Resources Center, Kauffman is also excited for the potential the continuing dam removal project holds for other kinds of research as well. Trained in how to build dams when he got his undergraduate engineering degree, Kauffman finds it compelling to now be involved in what he notes is the young science surrounding dam removal, which he says is only a couple decades old.
Were learning a lot about how the Brandywine Creek acts during floods and droughts. Were learning so much about how rivers can recover, Kauffman said. Thats what has been amazing: weve seen the results very quickly.
Kauffmans background prompts him to study water flow and the physical impacts on rivers and creeks having dams removed. One of the biggest impacts of dam removals from that perspective is the reduction in flooding events or their severity, since free-flowing waterways do not have as much water in normal conditions, meaning it takes more rain to cause them to flood.
The research even goes beyond hydrology and fisheries, with UDs Center for Historic Architecture and Design involved in evaluating the historic value of the Brandywine Creeks dams and Shreeram Inamdar of the College of Agriculture and Natural Resources studying changes in water quality brought about by dam removal. (Some dam removal actually opens up portions of the dam to allow the river to flow but aids in historic preservation by shoring up other parts of the structure so they can better stand up to the passage of time. Free flowing rivers also naturally filter excessive nutrient pollution from surface water, the subject of Inamdars research.)
Brandywine Shad 2020 has plans in place to remove dams 3, 4 and 6 when it can raise the money to do so, with dams 2 and 5 marked for fish ladders or other passages due to their historic value or infrastructure necessity. When completed, this phase will reach up to Hagley Museum and open three miles of river and acres of new habitat for diadromous fish and natural water filtration.
Both Hale and Kauffman said that as the work and research continues, those involved in the effort are learning things about urban, highly dammed waterways that could inform work in other parts of the state and the larger Delaware Bay and River watershed. Increasing scientific data on American Shad could help surrounding states make decisions about how to manage the fishery.
What we know now
But whatever the future holds for additional dam removals and scientific publications, Hales research this summer and fall show improvements are already underway. He noted that American Shad were once very abundant fish, dubbed the founding fish by John McPhee for its importance to the American colonial diet, but the combination of dams, pollution and other human impacts have severely reduced the stock.
The reestablishment of a native, natural, well-performing ecosystem is essentially the goal, and capturing juvenile shad there at that location is suggesting that that is on track and that removing the dam is actually beneficial to the wild ecosystem, Hale said. So we're opening up available habitat. We're seeing juvenile progeny. We are essentially documenting what could result in population rebuilding or recovery.
Article by Mark Jolly-Van Bodegraven | Photos by Mark Jolly-Van Bodegraven | October 22, 2020 | Originally published in UDaily
