Ospreys experienced widespread breeding woes around the Chesapeake Bay this past spring and summer, new survey results show.
The survey findings, announced by the Center for Conservation Biology of the College of William & Mary, reinforce concerns voiced earlier this year that the popular fish hawks could be on the wane across the estuary. They also draw fresh scrutiny to a controversial proposal to limit commercial harvests in the Bay of Atlantic menhaden, a staple of most ospreys’ diets.
During the 2025 breeding season from March through August, the center collaborated with federal, state and local agencies, nonprofit groups, the Virginia Aquarium and Washington College to monitor 1,025 pairs of ospreys in 23 different areas around the Bay’s mainstem and along its rivers.
While ospreys nesting in upriver areas with low salinity water are doing well, those nesting in far more extensive brackish water did not produce enough young to sustain the overall population in the Bay, the survey found. Indeed, 74% of the osprey pairs in those higher salinity waters produced no young at all.
“If the breeding performance observed over the past several years continues, the Baywide osprey population is predicted to decline,’’ said Bryan Watts, the center’s director. “In many areas, this decline has likely been ongoing for at least several years.”
The center has been tracking osprey breeding problems for years in Mobjack Bay, which lies between the Rappahannock and York rivers in Virginia. In 2024, Watts broadened the study to include collaborators and to monitor nesting in 12 areas in Maryland and Virginia.
The 2024 survey found unsustainable levels of reproduction among ospreys in higher salinity waters, where they are thought to be dependent on menhaden for food. The new survey found poor breeding was even more widespread, reaching into areas with moderate salinity.
To maintain the overall population, research has found that osprey pairs need to produce 0.8 to 1.3 chicks per nest, Watts said. Birds in high-salinity water above 18 parts per thousand averaged just 0.25 young per nest. In waters with moderately high salinity of 12 to 17.9 parts per thousand, osprey pairs averaged 0.31 young per nest.
Only those birds nesting in waters with salinity of less than 5 parts per thousand, where they feed on different fish, yielded a sustainable reproductive rate, he said.
As in 2024, the latest survey found that many osprey pairs did not even lay eggs, Watts reported. In what he said was a first, “a significant number” of pairs flew off at the height of the spring nesting season, in some cases abandoning eggs in their nests. Many returned later in June.
High winds and heavy rains caused some nest failures, Watts said, but the survey found signs of widespread food stress in higher salinity waters, indicating many osprey chicks starved to death. When food is scarce, ospreys produce fewer young. While two-chick nests are common, two-thirds of those birds nesting in higher-salinity waters had only one chick, he reported.
Another sign of food stress is uneven development of chicks, as larger, earlier hatched nestlings tend to monopolize the few fish that adult ospreys bring to the nest, leaving the others to starve.
Previous survey findings spurred long-standing calls from conservationists and recreational fishing enthusiasts to shut down large-scale commercial harvests of menhaden in the Bay. They contend that Virginia’s menhaden fishing fleet, operated by Ocean Harvesters, is depleting the Bay’s stock of the fish. The fleet harvests menhaden under contract with Omega Protein, which processes the catch into fish oil and pet feed at its Reedville, VA plant.
Critics argue that the fleet’s menhaden harvest is diminishing the food supply not just for ospreys but also for Atlantic striped bass, a popular and economically valuable fish that spawns primarily in the Chesapeake’s tributaries.
Omega Protein and its supporters dispute those assertions. They point to a 2022 stock assessment for the Atlantic States Marine Fisheries Commission, which found that the coastwide population of menhaden is not being overharvested. And they cite survey findings by the Maryland Department of Natural Resources of a record number of juvenile menhaden in that state’s waters.
Virginia lawmakers commissioned but have since refused to fund a study of menhaden abundance in state waters. The reduction harvest in the Bay — which occurs only in Virginia because Maryland bans it — is already capped at 51,000 metric tons per year.
In August, though, the Atlantic States commission, which regulates near-shore fishing for migratory species, agreed to consider limiting the amount of menhaden that can be taken from Virginia waters at any point in the season.
The move wasn’t prompted by concerns over ospreys but instead by complaints from Maryland fishermen who harvest menhaden for use as bait in crabbing and other pursuits. Lynn Fegley, DNR fisheries chief, said the state’s commercial fishermen have reported meager harvests of menhaden in their pound nets the past two summers, not long after Omega’s fleet had conducted harvests in Virginia waters south of the Maryland border.
Omega Protein and its supporters argue the move is unwarranted and improper. But the Chesapeake Bay Foundation supports it, noting that Virginia’s bait fishery also has seen a sharp decline in its menhaden harvest. Citing figures from the Virginia Marine Resource Commission, the foundation said the menhaden harvest for bait dropped from 5.4 million pounds in 2019 to less than 1 million pounds in 2024.
The Atlantic States commission is expected to take up the issue at its meeting in February.
The story was revised after posting to clarify Omega Protein’s relationship to the fishing fleet harvesting menhaden for it.