Ecological Reference Points for Menhaden

Atlantic menhaden supports the largest fishery on the U. S. east coast. This filter-feeding clupeiod fish supports the largest fishery on the east coast, and provides important ecosystem services including serving as forage for other fishes, seabirds and marine mammals, and during its residence in estuaries may reduce levels of important nutrients through filtering phytoplankton from the water. Thus, there is strong interest from the management community to assess the potential for the application of an ecoystem-based approach to managing these fisheries. With the support from the Lenfest Ocean Program, we have evaluated key aspects of the biology and ecology of this species to provide the management community with tools to support an ecosystem-based approach to managing menhaden.

Understanding patterns in annual recruitments of Atlantic menhaden has been an important goal for management for many years. It is known that recruitments in the 1970s and 1980s were much greater than current levels. Our analyses considered patterns in recruitment of Atlantic menhaden to determine the potential for environmental abiotic factors to influence recruitment. We found a strong latitudinal spatial pattern and an important role for the Atlantic Multidecadla Oscillation in predicting recruitments. This work has been published as Buchheister et al. (2016).

The management community wants to assess ecological reference points for this species. To support this goal, we developed an Ecopath with Ecosim model of the northwest Atlantic coastal shelf (NWACS) ecosystem. This model relied heavily on previous efforts which developed regional ecopath models. Full technical documentation is available. We quantified associated tradeoffs of a range of alternative ecosystem-based references points for menhaden F and biomass (B), including F for maximum sustainable yield (FMSY), 0.5FMSY, proxies for current single-species F reference points, 75%B0, and 40%B0. Results indicated that striped bass (Morone saxatilis) was most sensitive to increases in menhaden fishing, due largely to strong dietary reliance on menhaden, but other higher trophic-level groups (birds, highly migratory species, sharks, and marine mammals) were also negatively impacted. The alternative reference points considered resulted in 1) variable menhaden biomasses (40-75% of B0) and yields (54-100% MSY), 2) up to a 60% decline in striped bass B and yield, 3) negative impacts on the B of ≤13% of modeled groups, and 4) positive impacts on the B of ≤6% of groups. The EwE simulations demonstrated the varied responses, potential winners and losers, and complexities resulting from alternative menhaden management strategies for menhaden. This works is under review as Buchheister et al. (201X).

Last revised: 4/4/2017