An adult female osprey on a nest in the York River. The resident pair in this territory arrived in early March and remained on the territory throughout the nesting season. Despite being resident, she never was documented to lay a clutch. Photo by Bryan Watts.
Additional studies and precautionary measures needed to protect these iconic species
Each spring, birders eagerly await the return of ospreys to the Chesapeake Bay—a welcome sight that signals the end of winter. An estimated 8,000 to 12,000 breeding pairs of ospreys live in the Chesapeake Bay, which is home to the largest breeding osprey population in the world. Since ospreys are sensitive to changes in their environment, they serve as a monitor of the health of the Bay.
So, when 2024 breeding performance results released by the College of William & Mary’s Center for Conservation Biology (CCB) showed that osprey chicks continue to starve in their nests in portions of the Bay where they typically depend on menhaden—a small, silvery, nutrient-packed fish—for food, the findings intensified ongoing, decades-long concerns.
According to a press release issued on September 13, 2024, by the CCB, osprey chicks aren’t surviving at rates that sustain the population. A survey monitored 571 osprey pairs in 12 sites in Virginia and Maryland during the nesting season (March through August). Ten study areas were located within the main stem of the Bay, where salinity exceeded 10 parts per thousand (ppt), and ospreys are highly dependent on menhaden. Two additional study areas (used for comparison) were located on upper tributaries within tidal fresh waters, where salinity was less than 1 ppt, and ospreys feed primarily on catfish and gizzard shad.
The generally accepted reproductive rate for population maintenance is 1.15 young/pair. Breeding performance varied between the higher-salinity sites—ranging from minor, moderate, and major deficit. However, the reproductive rate within the tidal freshwater sites was 1.36 young/pair, which is above the maintenance target (surplus).
“It’s clear to researchers that ospreys are struggling due to food stress, but the starvation issue is mostly confined to the main stem of the Bay, where waters are greater than 10 ppt salinity,” says Bryan Watts, Ph.D., director of the CCB. “We do not know why menhaden have become less available to ospreys. The osprey-menhaden issue is a moving target. Some have suggested that ongoing harvest, warming waters, water quality, or other factors are impacting menhaden in the Bay. However, we do know that osprey broods [groups of chicks] are starving in their nests and that there is not enough menhaden in their diet to support sustainable reproductive rates.”
In addition to starvation, scientists and researchers are also observing uncharacteristic behaviors among ospreys. According to Watts, a large number of osprey pairs didn’t lay clutches during the 2024 nesting season. This is the first time that this behavior has been documented on a large scale within the Chesapeake Bay. Researchers believe that the most likely explanation is that the females didn’t reach the nutritional condition required to produce eggs.
Single-chick broods and asymmetric broods were also widespread throughout the Bay in 2024. Asymmetry develops when food coming into the nest is inadequate to feed all of the chicks—resulting in a dominance hierarchy, which allows the dominant chick to monopolize access to food. Depending on the available food supply, one or all of the chicks may starve.
“Each year, my team and I band ospreys along a 45-mile stretch of the middle and lower Patuxent River, from Jug Bay to the river’s mouth at Solomons Island,” says Greg Kearns, senior park naturalist for the Maryland-National Capital Park and Planning Commission (MNCPPC) at the Patuxent River Park. “As part of our work, we track reproductive trends by noting the number of chicks per nest and the total banded. Between 2013 and 2024, the number of nests producing only a single chick has increased, while those with two or three chicks has noticeably declined, especially in the lower, higher-salinity portions of the river—a sign of decreasing overall productivity. These are preliminary results, which are unpublished and have not been peer reviewed. However, we observed these declines long before they became a broader concern.”
Top: An osprey carries a menhaden to its nest platform on Poplar Island in Talbot County. Osprey will often rearrange a prey fish in its talons so the head is facing forward, making their meal more aerodynamic in flight. Photo by Will Parson/Chesapeake Bay Program. Bottom: Juvenile menhaden swim in Spa Creek in Annapolis. Menhaden are schooling fish that filter feed on algae and zooplankton in the water column. Photo by Will Parson/Chesapeake Bay Program. Right: A symmetrical brood within the upper James River reference site. Symmetric broods are maintained when enough food is delivered to nests to support all young in the brood. Nestlings develop at the same rate and have the same appearance. Photo by Bryan Watts.
The Role of Menhaden in the Bay Ecosystem
During the past 20 to 30 years, the baywide community has continued to sound the alarm about the availability of menhaden in the Bay. Scientists, researchers, commercial fisheries, watermen, conservationists, and recreational anglers and crabbers have noticed warning signs. (There is not a recreational fishery for menhaden in Maryland since the fish are very oily, which makes them unpalatable. However, many anglers and crabbers rely on them for bait.)
“We’ve been seeing red flags in the Chesapeake Bay during the past few decades—many of which are right here in Maryland,” says Allison Colden, Ph.D., Maryland executive director, Chesapeake Bay Foundation (CBF). “Maryland watermen aren’t meeting their menhaden quotas, citing that their harvests are down compared to previous years. In addition, the issues we’re seeing with ospreys are being recorded as far north as Poplar Island and have raised concerns about the importance of protecting other species that feed on menhaden.”
Referred to as the “most important fish in the sea,” menhaden are forage fish that serve as a critical part of the food chain in the Bay. They feed on phytoplankton and zooplankton, which they filter from the water. In turn, menhaden are eaten by various predators, including striped bass, bluefish, bald eagles, ospreys, dolphins, and whales. Some studies show that menhaden comprise approximately 75 percent of an osprey’s diet in higher-salinity areas of the Bay—underscoring the importance of determining why they are less available to ospreys.
According to CBF, the Bay is one of the most important nurseries for menhaden. Their eggs hatch in the open ocean before drifting as larval young on currents into the Bay.
In response to growing concerns about the availability of menhaden in the Bay and the disruption to the food chain, the Atlantic States Marine Fisheries Commission (ASMFC), which manages the fishery for the 15 states that share the coastline and establishes limits for both the coastwide and Chesapeake Bay harvests, first set a cap for the industrial menhaden harvest in the Bay at 109,020 metric tons in 2006. The Bay cap was reduced to 87,216 metric tons in 2013 and to 51,000 metric tons in 2017 to reflect more recent harvest levels.
Zenon Vasquez works aboard Captain Boo Polly’s workboat, hauling menhaden caught with pound nets on the Chesapeake Bay west of Barren Island in Dorchester County in June 2020. Photo by Carlin Stiehl/Chesapeake Bay Program.
A Contentious Issue
Top: Menhaden is often used as bait to catch both blue crabs or blue catfish. Photo by Will Parson/Chesapeake Bay Program. Bottom: An asymmetric brood within the lower Chesapeake Bay. Following the loss of the third young, these two young remain. The two siblings are noticeably different in size, with the smaller young being 50% the mass of the larger. Photo by Bryan Watts.
Although there is a lot of speculation among the baywide community regarding the availability of menhaden, the issue remains a source of disagreement, and a definitive cause has not yet been determined. Although the osprey-menhaden connection is complex, the issue is further complicated by the interests of the industrial menhaden fishery and politicians—making it a controversial topic of discussion within the Bay.
Omega Protein Corporation, a subsidiary of the Canadian multinational seafood company, Cooke, Inc., is the only industrial menhaden fishery in the Bay and along the Atlantic coastline. The company targets menhaden for the reduction industry, which involves grinding them into fishmeal or fish oil to use in other industries, such as cosmetics, nutritional supplements, pet food, and other consumer products, as well as feed for livestock and fish farms.
In the past, reduction plants were located throughout the East Coast. However, Virginia is currently the only state that still allows reduction fishing for menhaden in its waters. All other states have banned the practice. In fact, nearly 75 percent of all menhaden caught on the Atlantic Coast is harvested by Omega Protein, which operates the last remaining reduction facility on the East Coast in Reedsville, VA. But although industrial fishing only occurs in Virginia waters, it impacts the entire Bay.
“It surprises me that a Canadian-owned company is allowed to operate in U.S. waters and remove such a large biomass of a critical keystone species from the Bay,” Kearns says. “It seems unlikely that it would not have some impact on the ecosystem. It’s common sense. We just don’t know the full extent.”
Indeed, Omega Protein has continued to raise concerns about menhaden management in the Chesapeake Bay. According to a blog post written in 2021 by Chris Moore, Virginia executive director, CBF, the company has a documented history of fish spills, which result when the nets break and spill thousands of dead fish into the water, as well as environmental and regulatory violations, including Clean Water Act violations. In addition, it exceeded the Chesapeake Bay harvest cap in 2019. Perhaps most concerning, Omega Protein refuses to cooperate or share its harvest data with scientists and researchers who are studying the Bay’s menhaden population.
“Menhaden reduction fishing data is confidential,” Colden says. “Omega Protein, however, knows exactly where, when, and how much menhaden is taken from the Bay since they harvest it. But they don’t share the data publicly, so we don’t have the complete picture. We need more information to help us better manage menhaden.”
In addition to the industrial menhaden fishery, politics also plays a role in menhaden management. In January 2024, Virginia’s House of Delegates Studies Subcommittee unanimously delayed consideration of House Bill 19 (HB 19) until 2025—a major legislative setback that prevented scientists from advancing their knowledge of this critical species. The bill would have funded a comprehensive study of the menhaden population, which would help address significant issues, including the impacts of climate change and industrial fishing.
At the time of writing, Virginia is in the middle of a legislative session, and House Bill 2713 (HB 2713) is currently under consideration. The bill would require Virginia to conduct a study of the status of menhaden in Virginia’s portion of the Chesapeake Bay.
The Establishment of a Workgroup
Prompted by the 2024 osprey survey results, which showed low nesting success in higher-salinity portions of the Bay, the ASMFC voted to establish a workgroup in August 2024 to assess the need for precautionary measures and additional protections from industrial fishing.
The motion, which was proposed by Colden, a member of Maryland’s ASMFC delegation, directs the workgroup to consider management actions, including possible time of year and area closures, to protect predators that rely on menhaden for food in the Bay. The motion was unanimously supported by the Menhaden Management Board.
“The Chesapeake Bay menhaden harvest caps are just one precautionary measure,” Colden explains. “From struggling osprey populations to dismal menhaden bait landings, it’s clear that additional precautions are needed. This ongoing issue warrants more in-depth discussion. Seasonal fishing closures during the time of year when menhaden are most in demand by ospreys and other predators would help us better manage menhaden fishing in the Bay.”
“The 2024 osprey data adds to the growing concerns about the number of menhaden in the Bay and the importance of a robust menhaden population—[not only] for species that depend on them for food [but also] for the local economy,” Moore adds. “We must follow a precautionary, ecosystem-based approach to [set] limits on the menhaden fishery. That approach must include the study of the industrial fishing impacts to the Bay as well as [the consideration] of seasonal fishing closures from the Atlantic States Marine Fisheries Commission.”
The workgroup presented an update to the Menhaden Management Board at its October 2024 meeting. Colden says the workgroup decided to take a deeper dive into the issues that affect menhaden and collect additional data. They would also like to bring in more experts to help analyze the issues and make suggestions. The workgroup will present its findings to the board at the spring meeting on May 5–8.
Left: An osprey brings a menhaden back to its nest and partner on Shipping Creek on Kent Island in Stevensville. Photo by Will Parson/Chesapeake Bay Program. Top: Norah Carlos of the Chesapeake Bay Foundation demonstrates the first half of the “kiss and twist” method of preparing a menhaden for use as bait for a crab pot during an educational program on the waters of Smith Island. Photo by Will Parson/Chesapeake Bay Program. Bottom: An adult female osprey carries a menhaden to a nest in the Chesapeake Bay. Osprey with menhaden has been an iconic sight over Bay waters for hundreds of years. The view has been much less common in recent years. Photo by Bryan Watts.
Future Outlook
The formation of a workgroup is a testament to the ASFMC’s recognition of the need for additional precautionary measures on the industrial menhaden fishery. The relationship between ospreys and menhaden is critical, and the role of menhaden in the food chain cannot be disputed.
Although scientists have some data on the menhaden population in the Bay, there is a lack of specific information with regard to their distribution, which has resulted in ongoing concerns about overfishing and the impact on the Bay ecosystem. Clearly, more targeted research and studies are needed to understand the menhaden population within the Bay.
“Concern about menhaden and ospreys is an emerging issue with several strategic questions yet to be addressed,” Watts says. “During the next two years, we will continue to push the boundaries in the field and collect data designed to answer outstanding concerns. With help from fisheries scientists, industry, and the broader Bay community, I am confident that together we will have the sound science needed to tackle threats to the populations of both ospreys and menhaden.”
Special thanks to Valerie Keefer, Maryland communications & media relations manager, CBF, and Kenny Fletcher, director of communications and media relations, CBF.
