If you’re paying any attention to decisions being made about the Chesapeake Bay right now, you’re probably aware that there are some big things happening centered around a little fish called menhaden.
It seems that this fish is becoming more well known to the general public but even 10 years ago, many people were unaware of this particular species. Menhaden are important forage fish, which means they feed many of the larger, predatory fish and bird species that are iconic to our region. They are also a major, and somewhat controversial, fishery in Virginia, with a significantly smaller fishery in Maryland.
Menhaden are unique because they feed on phytoplankton which are mostly microscopic plants that drift along in waterways. As juveniles, menhaden eat more zooplankton (animals) but transition to eating more phytoplankton as adults [1]. This diet is why menhaden have a high concentration of oil in their tissues, as many phytoplankton use lipids (aka fats) to help them stay buoyant and at the surface of the water so they can photosynthesize. This high fat concentration is why menhaden make up an important fishery, as they are ground up and their oil is extracted for human supplements, pet food, fish meal for aquaculture, and fertilizer [2].
Menhaden also travel in large schools and they exhibit a special swimming behavior when they are eating, where they swim together in a circle to create a funnel that concentrates the phytoplankton in the center where they can more easily eat it. This schooling behavior allows them to be caught en masse using a purse seine, which typically uses two boats to encircle the school of fish in one giant net. The schools of fish are often found using planes that fly out to spot the schools and let the boats know where to go.
While many have questioned whether this fishery is experiencing overfishing, the most recent report by the Atlantic States Marine Fishing Commission (ASMFC) has cleared the fishery of this accusation [3]. In fact, the Marine Stewardship Council, the nonprofit that certifies global fisheries for sustainability based on many different factors, has listed the purse seine menhaden fishery as sustainable since 2019 [4].
However, the recent declines in osprey populations and the increased rates of failure in osprey nests among those that live along the mainstem Chesapeake Bay, has brought an increased concern in the impacts of the menhaden fishery on the larger Bay food web. As mentioned in our February critter feature, osprey that nest along the tributaries and feed on other species of fish seem to be doing fine. It is those that nest along the mainstem Bay and tend to feed heavily on menhaden that are not doing well. We are also seeing a decline in rockfish (aka striped bass), which also feed heavily on menhaden.
It seems important to be aware of the fact that the AMSFC report that said overfishing was not occurring was a single-species assessment, as opposed to a multi-species model that looks at interactions between different species. It is also important to note that the Marine Stewardship Council acknowledges several weaknesses in the assessment of their Menhaden data including the lack of a coastwide assessment of the Menhaden stock (so the focus is more narrow than they’d like) and they have only a small amount of data on menhaden predators which, if they had, could be used to better improve the ecosystem reference points used in the fishery management plan.
This makes it seem like additional information is needed to understand whether or not the current stock of mid-Atlantic/Chesapeake Bay Menhaden is truly healthy or not. Until that data is obtained and analyzed, it’s not a bad idea to reduce the total catch of Menhaden and see if that improves things for some of their predators.
The ASMFC is currently taking public comments on changes to the Menhaden quota for the Chesapeake Bay fishery (through October 9th, 2026). You can learn more and make comments here; https://asmfc.org/actions/atlantic-menhaden-draft-addendum-ii/
References:
[1] F.C. June, F.T. Carlson. Food of young Atlantic menhaden, Brevoortia tyrranus in relation to metamorphosis. Fish. Bull., 68 (1971), pp. 493-512 https://spo.nmfs.noaa.gov/sites/default/files/pdf-content/1970/683/june.pdf
[2] https://www.fisheries.noaa.gov/species/atlantic-menhaden/commercial
[3] https://asmfc.org/species/atlantic-menhaden/
[4] https://fisheries.msc.org/en/fisheries/u.s-atlantic-menhaden-purse-seine/@@assessments
Excellent article.