Ospreys in several sections of the Chesapeake Bay are having trouble breeding, because of what William & Mary researchers believe is a lack of available food.
The study released Wednesday by the university’s Center for Conservation Biology is the latest in a series that have drawn significant attention because of claims researchers make about the controversial Chesapeake Bay menhaden fishery.
Last year, the center said it was seeing the lowest number of osprey chicks since the information started being recorded in the 1970s.
The study said osprey chicks were dying of starvation and linked the issue to a scarcity of menhaden from overharvesting.
“It does seem to be getting worse in that more and more (osprey) nests are failing,” Bryan Watts, longtime director of the center, told WHRO at the time.
Many environmental groups and recreational anglers have been pushing Virginia to ban industrial menhaden fishing in the Chesapeake Bay.
Omega Protein, the only company that does so, maintains there’s no evidence backing up concerns about overharvesting, pointing to federal surveys finding the East Coast menhaden population is healthy. (Earlier this year, Virginia’s General Assembly delayed a bill that would’ve funded a deeper study of the local menhaden population.)
The Center for Conservation Biology acknowledged in a news release this week that its previous osprey research received criticism for focusing on one section of the watershed: Mobjack Bay along the Middle Peninsula.
That drove the team to widen this year’s scope to eight additional sites including the bayside Eastern Shore and the Lynnhaven, Elizabeth, Poquoson and York rivers. The goal was to focus on spots where the species is believed to depend on menhaden.
The mean reproductive rate for osprey pairs nesting in these areas did not meet levels required to maintain the population, according to the new research, though there was some variation between the study areas.
Overall, the reproductive rate was about half of what researchers believe is needed.
“The osprey breeding performance in the main stem of the Bay that was documented in 2024 (and for the past several years) is not sustainable,” researchers wrote. “In the absence of immigration from other parts of the Bay or outside of the Bay the population would be predicted to decline.”
The news release noted that researchers did not include data from a survey recently conducted by the U.S. Geological Survey on the lower Choptank River, because the information has not yet been publicly released.
The USGS presented last month to the menhaden board of the Atlantic States Marine Fisheries Commission, reporting that the long-term osprey population along the Atlantic coast had increased by nearly 600% between 1966 and 2022.
However, over the past decade or so, data suggests the population is declining in the bay, agency researchers said. They added that it’s not yet clear what could be causing the decline, noting that “populations don’t grow forever.”
“It's important to keep in mind that there are many factors and stressors that can affect osprey reproduction,” Barnett Rattner with the USGS’ Eastern Ecological Science Center told board members.
“Yes, limited food ability can have effects on reproduction, as well as depredation competition, disease events, inexperienced breeders. There can be storms, weather events, and even very hot weather, like we've experienced this year that can affect reproduction, certainly environmental contaminants and also water clarity that's needed for the males to catch their prey.”
In a statement following the August meeting, Omega Protein spokesperson Ben Landry said those attending “could only come away with one clear message from the respected researchers at USGS, and that is the osprey's numbers have dramatically increased.
“Any challenges that the seabirds face are complex and multi-faceted, occurring in numerous locations on both the Atlantic and Pacific coasts, and cannot be blamed on the menhaden harvest in the Chesapeake Bay,” Landry wrote.
The Atlantic commission’s menhaden board, which regulates the fishery coastwide, ultimately voted to study more restrictions to consider later this year.
