Macroscale drivers of Atlantic and Gulf Menhaden growth

• Published in: Fisheries Oceanography
• Main Authors: Midway, Stephen R., Schueller, Amy M., Leaf, Robert T., Nesslage, Geneviève M., Mroch, Raymond M.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 2020
• Subjects: North Atlantic
• Online Access: http://dx.doi.org/10.1111/fog.12468; https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1111%2Ffog.12468; https://onlinelibrary.wiley.com/doi/pdf/10.1111/fog.12468; https://onlinelibrary.wiley.com/doi/full-xml/10.1111/fog.12468

Abstract The identification of anthropogenic and environmental drivers on length‐at‐age of fish stocks is important to understanding ecosystem dynamics and harvest intensity. We evaluated coastwide annual growth of n = 187,115 Atlantic Menhaden ( Brevoortia tyrannus ) and n = 299,185 Gulf Menhaden ( B. patronus ), using samples collected from the North, Mid‐, and South Atlantic from 1961 to 2016 and across the Gulf of Mexico from 1977 to 2016. Using hierarchical models of age 1 growth and age 2 growth, we evaluated a suite of candidate predictors including fishery landings, easterly (U) and northerly (V) wind velocity, river discharge, juvenile abundance, and the Atlantic Multi‐decadal Oscillation (AMO). We found age 2 growth rates were smaller than age 1 growth rates for both species and that Atlantic Menhaden growth rates were 3–4 times greater than Gulf Menhaden. Age 1 growth rate of Atlantic Menhaden was positively affected by landings lagged by one year, indicating a density‐dependent mechanism. In addition, AMO (negative effect), and wind U (positive effect) and wind V (negative effect) in the North Atlantic region were significant factors influencing coastwide age 1 Menhaden growth. Wind V (negative effect) and AMO (positive effect) influenced age 1 Gulf Menhaden growth. No environmental factors were found to have an effect on age 2 Atlantic Menhaden growth, and AMO was the only significant predictor (weak negative effect) of age 2 Gulf Menhaden growth. Fishing pressure was the primary influence on age 1 Atlantic Menhaden growth, whereas age 1 Gulf Menhaden growth was primarily influenced by environmental conditions.