Atlantic menhaden caught as part of Maryland's Estuarine Fish Community Sampling Program. Photo © Frank Marenghi, MD DNR.
Atlantic menhaden (Brevoortia tyrannus) occupy estuaries and coastal waters from Nova Scotia to northern Florida and are believed to consist of a single population. Adult and juvenile menhaden form large, near-surface schools, primarily in estuaries and nearshore ocean waters from early spring through early winter. By summer, menhaden schools stratify by size and age along the coast, with older and larger menhaden found farther north. During fall-early winter, menhaden of all sizes and ages migrate south around the North Carolina capes to spawn.
Sexual maturity begins as early as age one to just before age three, with major spawning areas from New Jersey to the Carolinas. The majority of spawning primarily occurs offshore (20-30 miles) during winter. Buoyant eggs hatch at sea, and larvae are carried into estuarine nursery areas by ocean currents. Juveniles spend most of their first year in estuaries, migrating to the ocean in late fall.
Menhaden are very efficient filter feeders. Water is pushed through specialized gill rakers that are formed into a basket that allows them to capture plankton. Menhaden are an important component of the food chain, providing a link between primary production and higher organisms by consuming plankton and providing forage for species such as striped bass, bluefish, and weakfish, to name just a few.
The Atlantic menhaden commercial fishery consists of a reduction fishery (named because it "reduces" the whole fish into fish meal, fish oil, and fish solubles) and a bait fishery. The reduction fishery first began in New England during the early 1800s and spread south after the Civil War. The reduction fishery grew with the advent of purse seines in the mid-1800s and reached peak landings in 1956 at 712,100 metric tons (mt). At the time, over 20 menhaden reduction factories ranged from southern Maine to northern Florida. In the 1960s, the Atlantic menhaden stock contracted geographically, and many of the reduction factories north of the Chesapeake Bay closed due to a scarcity of fish. Consequently, reduction landings dropped to 161,000 mt in 1969. In the 1970s and 1980s, the menhaden population began to expand (primarily due to a series of above average year classes entering the fishery), and reduction landings rose to around 300,000-400,000 mt. Adult menhaden were again abundant in the northern half of their range and, as a result, reduction factories in Canada and New England began processing menhaden again by the mid-1970s. However, by 1989 all shore-side reduction plants in New England had closed, mainly because of odor abatement regulations.
During the 1990s, the Atlantic menhaden stock contracted again, largely due to a series of poor to average year classes. Over the next decade, several reduction plants consolidated or closed, resulting in a significant reduction in fleet size and fishing capacity. By 2006, there was only one remaining reduction plant in operation on the Atlantic coast processing menhaden into fishmeal and oil. This is the Omega Protein plant, located in Reedville, Virginia, which is still operational today. In 2019, roughly 150 thousand mt were landed for reduction purposes.
Commercial landings in 2019, including reduction, bait, bycatch, and episodic event landings, were 208,837 mt, or 96% of the TAC. This represents a 9% decrease in landings from 2018.
In February 2020, the Atlantic Menhaden Board accepted the results of the Atlantic Menhaden Single-Species and Ecological Reference Point (ERP) Assessments and Peer Review Reports for management use. The single-species assessment acts as a traditional stock assessment using the Beaufort Assessment Model (BAM), and indicates the stock is not overfished or experiencing overfishing relative to the current single-species reference points. The ERP assessment evaluates the health of the stock in an ecosystem context, and indicates that the fishing mortality (F) reference points for menhaden should be lower to account for menhaden’s role as a forage fish. The ERP assessment uses the Northwest Atlantic Coastal Shelf Model of Intermediate Complexity for Ecosystems (NWACS-MICE) to develop Atlantic menhaden ERPs. NWACS-MICE is an ecosystem model that focuses on four key predator species (striped bass, bluefish, weakfish, and spiny dogfish) and three key prey species (Atlantic menhaden, Atlantic herring, and bay anchovy). These species were chosen because diet data indicate they are top predators of Atlantic menhaden or are key alternate prey species for those predators. A more detailed overview of the stock assessments is available here. This tool allows managers to evaluate the tradeoffs between Atlantic menhaden harvest and predator abundance to set reference points that take into account menhaden’s role as a forage fish.
In August 2020, the Board approved the following ERPs in the management of Atlantic menhaden:
ERP target: the maximum fishing mortality rate (F) on Atlantic menhaden that sustains Atlantic striped bass at their biomass target when striped bass are fished at their F target
ERP threshold: the maximum F on Atlantic menhaden that keeps Atlantic striped bass at their biomass threshold when striped bass are fished at their F target.
ERP fecundity target and threshold: the long-term equilibrium fecundity that results when the population is fished at the ERP F target and threshold, respectively
Atlantic striped bass was the focal species for the ERP definitions because it was the most sensitive predator fish species to Atlantic menhaden harvest in the model, so an ERP target and threshold that sustained striped bass would likely provide sufficient forage for other predators under current ecosystem conditions. For the development of the ERPs, all other focal species in the model (bluefish, weakfish, spiny dogfish, and Atlantic herring) were assumed to be fished at 2017 levels.
The fishing mortality rate in 2017 was below both the ERP target and threshold, indicating that the stock was not experiencing overfishing. Fecundity (a measure of reproductive capacity) in 2017 was above both the ERP target and threshold, indicating the stock was not overfished.
Atlantic menhaden are currently managed under Amendment 3 to the Interstate Fishery Management Plan (FMP). Amendment 3 established commercial quota allocations to strike a balance between gear types and jurisdictions, and to facilitate future growth in the fisheries. The amendment allocates a baseline quota of 0.5% to each jurisdiction, and then allocates the rest of the annual TAC based on historic landings between 2009 and 2011. This measure provides fishing opportunities to states which previously had little quota while still recognizing historic landings in the fishery. The Amendment also prohibits the rollover of unused quota, maintains the 6,000 pounds trip limit for applicable gear types following the closure of a directed fishery, and sets aside 1% of the TAC for episodic events in the states of New York through Maine. Lastly, the Amendment reduces the Chesapeake Bay cap, which was first implemented in 2006 to limit the amount of reduction harvest within the Bay, to 51,000 mt. This recognizes the importance of the Chesapeake Bay as nursery grounds for many species by capping reduction landings from the Bay to current harvest levels.
The current TAC for the 2021 and 2022 fishing seasons is 194,400 mt. The 2021-2022 TAC represents a 10% reduction from 2018-2020 TAC level. The Board approved the current TAC in October 2020 based on the ERPs approved in August 2020; this TAC level is estimated to have a 58.5% chance of being at or above the ERP F target in 2021, and a 52% chance of being at or above the ERP F target in 2022. It has a 0% chance of being above the F threshold in both years. In determining which level to set the TAC, the Board also considered recent updates to the fecundity (FEC) reference points, and current stock condition. According to the latest assessment results, the 2017 estimate of fecundity, a measure of reproductive potential, was above both the ERP FEC target and threshold, indicating the stock was not overfished.
A stock assessment update is scheduled for 2022 which will inform the TAC for 2023 and beyond.