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Within the intricate network of aquatic ecosystems, the American shad stands as a captivating enigma. This intrigue was recently explored in a webinar hosted by The Watershed Institute titled “The Mysterious World of the American Shad and Work to Bring Them Back to Our Waterways.” Led by The Watershed Institute’s Executive Director Jim Waltman and Princeton Hydro’s Senior Technical Director in Engineering and American shad expert Dr. Clay Emerson PE, CFM, the webinar explored the complex dynamics surrounding this iconic species, including its historical significance, unique migration patterns, and conservation efforts.
As the American shad embark on their annual upstream journey for spawning, the timing is especially poignant for a closer examination of this vital species and an exploration of strategies to safeguard and revive their populations. We invite you to enjoy our blog, which encapsulates the webinar’s key insights, and to watch the full recorded session made available by The Watershed Institute.
American shad (Alosa sapidissima) are the largest members of the herring family. Their closest relatives are herring, sardines, and menhadens. They are an anadromous fish species, like salmon and steelhead (Oncorhynchus mykiss), that live most of their life in the ocean and migrate to freshwater rivers and streams to spawn. The American shad migration routes span vast distances, from the St. Johns River in Florida to the St. Lawrence River in Quebec, showcasing their tenacity and adaptability.
Not only do American shad undertake astonishingly long journeys to spawn, they also showcase distinctive migratory behaviors. Unlike many other anadromous species, these resilient shad can complete multiple round trips from freshwater to the ocean over their lifespan, challenging the conventional notion of ‘one and done’ spawning observed in Pacific salmon (Oncorhynchus) and sea lamprey (Petromyzon marinus).
Young shad will remain in the rivers where they hatched for several months. Migration out to the ocean typically occurs in late summer in the south, and early fall in the north, typically when the shad are 3-4 inches in size. Then, after 3-6 years of growth at sea, the shad migrate back to fresh water to spawn. Some shad make the journey to their spawning grounds 5-6 times over the course of their lifetime. Shad’s affinity for their birthplace adds a fascinating layer to their story. Approximately 95% of shad return to the rivers where they were hatched, with only 5% straying to unfamiliar waters to spawn.
American shad’s unique hearing abilities are another noteworthy aspect. Endowed with specific biological features, shad exhibit exceptional sensitivity to water movements and noise, particularly attuned to sounds like clicks and echolocation. This acute sense plays a vital role in navigating their environment and evading predators such as dolphins.
Such intriguing characteristics make the American shad not only a vital component of aquatic ecosystems but also a subject of admiration and study among enthusiasts and conservationists alike.
Throughout history, American shad have held a vital place in the cultural heritage and economic prosperity of the United States, earning them the esteemed title of “America’s Founding Fish.” Within the Delaware River region, these fish were not merely sustenance but also integral to the fabric of indigenous Lenape culture. During the annual shad migration, rivers and streams overflowing with these prized fish provided essential nourishment and served as valuable fertilizer. Interestingly, in various Native American tribes, folklore depicts the shad as originating from the porcupine, likely owing to the fish’s notably bony structure.
In later American history, the significance of shad persisted. Renowned painter Thomas Eakins immortalized the tradition of shad fishing in his iconic 1881 masterpiece “Shad Fishing at Gloucester on the Delaware River,” while the state of Connecticut elevated the shad to the status of state fish, further cementing its place in American heritage.
Fishing for American shad was among the earliest established industries on the coast of North America, once providing abundant and affordable nutrition to the populace. However, the shad population peaked in the 1940s before experiencing a dramatic decline to its current depleted state.
Despite these challenges, the American shad perseveres as a symbol of resilience. Festivals along the Atlantic Coast, such as the Annual ShadFest in Lambertville, New Jersey, celebrate these fish while also advocating for their protection. Recognizing the historical importance of shad underscores the pressing responsibility to safeguard and preserve our natural heritage for future generations.
The construction of dams, historic overfishing, and pollution have all played significant roles in the decline of American shad populations.
Dams along the East Coast block access to vital spawning grounds. Currently, a staggering 40% of American shad habitat is obstructed by these barriers, resulting in the loss of more than a third of the population. By removing outdated dams that have outlived their usefulness, we not only improve water quality and natural habitat for myriad species but also reconnect shad to their historic spawning grounds.
Additionally, shad fall victim to inadvertent bycatch in various ocean fisheries. Pollution in our rivers and water quality issues emerge as another critical concern along with fluctuating water temperatures and dissolved oxygen levels that disrupt shad behavior and crucial life cycle events such as migration and spawning. Compounding these issues are the menacing presence of invasive species, which outpace shad in numbers and deplete food resources, posing a significant obstacle to their recovery efforts.
Amidst these challenges, there is hope. River restoration efforts, dam removals, and fish passage projects throughout the East Coast stand as beacons of progress.
Removing obsolete dams, culverts, and other man-made barriers; the implementation of fish passage projects; and river habitat restoration initiatives have shown promising results in directly aiding shad and other migratory aquatic species populations. Highlighted below are a few examples of dam removal initiatives that immediately yielded positive results:
The Nature Conservancy in New Jersey and Princeton Hydro are leading the removal of three outdated dams on the Paulins Kill River: the Columbia Lake Main and Remnant Dams (completed 2019), the County Line Dam (completed 2021), and Paulina Dam (slated for completion 2024). This collaborative effort will reconnect 45 miles of mainstream and tributaries for migratory fish species like American shad. The Columbia Lake Dam removal, New Jersey’s largest to date, began in July 2018 and showed promising results even before 100% completion. By April 2019, American shad were spotted 10 miles upstream from the former dam site for the first time in over a century, showcasing the resilience of this incredible species and the success of conservation initiatives.
In November 2016, the Musconetcong Watershed Association (MWA) and Princeton Hydro completed the Hughesville Dam Removal, opening up six miles of the Musconetcong to migratory fish. In the Spring of 2017, schools of American shad were observed above the dam, five miles from the river’s confluence with the Delaware River. After an absence of over 250 years, American shad made a triumphant return to the Musconetcong River sparking hope for the future.
Shad serve as a crucial benchmark species, offering valuable insights into the ecological health and diversity of our waterways. Conservation endeavors that facilitate the resurgence of the American shad not only represent a thrilling triumph but also stand as proof-positive of our capacity to assist migratory fish in reclaiming their natural habitats. In doing so, we safeguard their future and preserve the places they call home.
By understanding the biology, historical significance, and primary challenges of the American shad, we can work towards sustainable solutions that benefit both shad populations and the broader ecosystem. We invite you to delve deeper into the fascinating world of American shad by watching the full webinar:
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