Photo by Evelyn mcDermott
AUTHOR: Evelyn mcDermott
Life as a fledgling osprey isn’t easy: bald eagles and great horned owls are dangerous predators, and raccoons will sometimes steal eggs before they can even hatch. But despite numerous natural threats and generally harsh conditions, the most pressing dangers to the osprey population have always been a result of human activities.
Ospreys are found on every continent on Earth, excluding Antarctica. They are a migratory species, typically traveling south for the winter. In the spring, they return to their northern breeding grounds. One such spot is the Delaware Estuary. They build their nests on utility poles, trees, towers, and platforms built specifically for them. These nests are remarkably large; some reach up to 6 feet wide and 13 feet deep. Once an osprey pair builds a nest, they reuse and expand that same nest every year. One month after their arrival, in April, the ospreys’ nesting season begins. Each breeding pair typically lays one to four eggs, which take approximately 40 days to hatch.
Dichloro-diphenyl-trichloroethane (DDT) is an insecticide developed in the 1940s to combat malaria and other insect-borne diseases. Later, it was used to treat crops, livestock, homes and gardens. However, this incredibly effective and popular pesticide came with severe environmental consequences. DDT accumulates in fatty tissues, building up in organisms and the food chain.
For ospreys, the effects of DDT were devastating: Ospreys’ diet is 99% fish. When DDT washed into oceans and rivers, it entered the fish, then accumulated within ospreys after they ate those contaminated fish. After entering the body, DDT typically broke down into a metabolite called DDE. Exposure to DDE caused egg shells to thin, which caused eggs to be cracked before the chicks could be born. From the 1950s to 70s, the Delaware osprey population dropped significantly due to DDT and other contaminants. The nearby Chesapeake Bay ospreys also suffered, with the population plummeting an estimated 80% by the 1970s.
Concerns about the pesticide’s adverse effects on people and the environment, along with insects’ growing immunity lead to regulatory actions to restrict its use being introduced in the late 1950s and 1960s. Environmentalist Rachel Carson published Silent Spring in 1962, detailing the environmental dangers of DDT. Widespread public concern about DDT being a cancer-causing chemical and the damage it was causing to ecosystems spread shortly after its publishing.
The public’s unease, along with scientific evidence and practicality, eventually led to the EPA issuing a cancellation order for DDT in 1972, 30 years after it was first released. But by that time, DDT had already done serious damage to not only the osprey population, but also species such as bald eagles, brown pelicans and other birds of prey.
Thankfully, the osprey population stabilized soon after the ban, and eventually rebounded. Today, osprey populations in the Delaware Estuary have recovered as a result of conservation efforts and reduction of contaminants (including DDT). To this day, local volunteers in Delaware work to monitor ospreys, and build safe nesting platforms. This recovery makes one of Delaware’s “greatest conservation success stories.”
Despite this resounding success, the ospreys’ survival is anything but guaranteed. Current data suggests that ospreys in the Chesapeake are facing a new crisis: they are unable to feed their young. In some areas of the bay, less than half of the chicks necessary to sustain the population are surviving — rates worse than during the height of DDTs. Ospreys are an indicator species, meaning their success reflects the overall health of the ecosystem. These species are treated as early warning signs of larger issues, and the ospreys’ current struggles are certainly raising alarm bells.
The issue driving this dramatic drop in reproductive success seems to be a scarcity of a forger fish called menhaden. Menhaden are a keystone species in the Chesapeake, filtering the water and acting as an important food source for various species — including ospreys. But over the last 40 years, the number of menhaden that osprey brought to their nest dropped by 80%. These fish have some of the highest energy density among the ospreys diet, making their loss even more impactful.
The exact cause of this decline is not confirmed, but some believe that industrial fishing along the Atlantic Coast is to blame. Omega Protein is the last menhaden reduction fishery operating on the coast today, located in Virginia. It is supplied by Ocean Harvesters, which is permitted to catch 350 million pounds of menhaden annually, including 110 million pounds from the Chesapeake. The Atlantic States Marine Fisheries Commission (ASMFC), which manages the conservation of various fish species across the Atlantic Coast, found that coastwide overfishing is not happening. However, the status of menhaden within the Chesapeake is still largely unknown.
In 2025, Maryland bait fisheries raised concerns about dramatic drops in their menhaden catches. Fishery officials suggested that Ocean Harvests might be at fault, prompting Ocean Harvesters and Omega Protein to point out a lack of scientific evidence. These concerns, along with reports of the ospreys’ reproductive struggles, led the ASMFC to consider Bay harvest cuts at its August meeting.
On Aug 5, 2026, the commission heard arguments from both sides on whether to change the limits on harvesting in the Bay. One Virginia delegate, Adele McClure, argued that the commission should wait for studies proving that changes are necessary before taking action. A spokesman for Ocean Harvesters warned that cuts to their allowed amount of fish would lead to lay-offs. On the other side, sports anglers and conservationists argued that the commission ought to install precautionary measures, rather than risk further disrupting the ecosystem of the Chesapeake by waiting for hard evidence.
In the end, the commission voted in favor of putting these potential cuts out for public comment, and will schedule public hearings. These cuts could reduce the Chesapeake Bay Reduction Fishery Cap by up to 50% if approved. The commission expects to make its final decision at its annual meeting in November 2026.
In a complicated world so full of pressing environmental and social issues, tackling even one can feel like a hopeless endeavor. The ospreys’ history stands out as an example of how we can, and have, helped restore species and ecosystems. Today, the ospreys face an uncertain future once again. Now we should look to our own past for guidance, and choose to pull ospreys off the path we set them down once again.
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