Calibration of a bioenergetics model linking primary production to Atlantic menhaden Brevoortia tyrannus growth in Chesapeake Bay

Growth and potential productivity of young-of-the-year (YOY) Atlantic menhaden Brevoortia tyrannus, a key forage fish, were investigated in Chesapeake Bay. A coupled foraging and bioenergetics model was developed to predict the dependency of menhaden size on chlorophyll a (chl a) and water temperatures in the bay. Substantial improvements were made to functional responses previously developed to describe YOY menhaden filtering efficiency on phytoplankton and swimming speed while filter feeding. Model output was calibrated to correspond to observed lengths of field-collected menhaden over an 11 yr period (1995 to 2005) by adjusting the percentage of chl a available to menhaden in the model. The model effectively represents variability in menhaden length in response to changes in chl a and temperature, indicating that only 9.2% of available chl a was required for menhaden to grow to lengths observed in the bay. In simulations of growth potential by bay region, the oligohaline (upper) region had the highest growth potential with decreasing potential in the mesohaline (middle) and polyhaline (lower) regions of the bay. Our results represent the first rigorous calibration and evaluation of a coupled foraging-bioenergetics model for Atlantic menhaden and establish a quantitative link between chl a standing stock and menhaden growth potential.