Ecological reference points for Atlantic menhaden

Tue 28 July 2020, noon EST

Dr. David Chagaris is a research assistant professor at the University of Florida, IFAS Nature Coast Biological Station.  Dr. Chagaris is a quantitative fisheries scientist that develops population dynamic and ecosystem models that incorporate environmental drivers, food web dynamics, and habitat interactions in order to understand how fisheries resources and marine ecosystems respond to fishing and environmental change. Those models are then used to improve population assessments, screen policy options for unintended consequences, evaluate ecosystem effects of natural and anthropogenic perturbations, and develop new management reference points that account for ecosystem interactions and the uncertainty therein.

Atlantic menhaden (Brevoortia tyrannus) are an important forage fish for many predators, and they also support the largest commercial fishery on the U.S. east coast.  Menhaden management now calls for ecological reference points (ERPs) that account for their role in the ecosystem.  The goal of this work was to develop menhaden ERPs using Ecopath with Ecosim.  An existing Ecopath with Ecosim model of the Northwest Atlantic Continental Shelf (NWACS) was reduced in complexity from 80 to 15 groups in order to link the dynamics of menhaden with key managed predator species and evaluate tradeoffs in harvest policies.  ERPs were based on the relationship between equilibrium biomass of striped bass and menhaden fishing mortality.  The ERPs are the menhaden F rates that maintain striped bass at their biomass target and threshold, when striped bass are fished at their target rate.  Our approach represents a first steps towards ecosystem-based fishery management in the U.S and could be applied to other forage fisheries.