Ecosystem Drivers of U.S. South Atlantic Nearshore Stocks with Potential Applications for Assessments

Effective implementation of an ecosystem approach to fisheries requires a thorough understanding of the relative influence of various ecosystem factors on fish populations. Ecosystem factors can be categorized as biophysical, anthropogenic, or trophodynamic, each typically inducing bottom-up, top-down, or bidirectional forcing, respectively. Our goal is to elucidate the relative importance of selected ecosystem factors on population growth rates of several nearshore fish and invertebrate species inhabiting the U.S. South Atlantic (SA) region. Leveraging data from the Southeast Area Monitoring and Assessment Program coastal trawl survey, we generated annual abundance indices for well-sampled species from 1990–2013 using generalized linear and additive models. Using multivariate autoregressive state-space (MARSS) modelling, we analyzed species abundance indices in conjunction with lagged time series of biophysical (primary productivity, climate indices) and anthropogenic (landings by gear type) factors. MARSS model outputs will allow us to infer the relative importance of density-dependence, food web interactions (both species-on-species effects), environmental stochasticity, and harvest pressures (both covariate-on-species effects) to the abundance dynamics of our populations of interest. Effects of significant biophysical and trophodynamic drivers on population abundances identified by our analysis could be directly or indirectly incorporated (depending on assessment model type) in future assessments of SA coastal stocks.