Macroscale drivers of Atlantic and Gulf Menhaden growth

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. K E Y W O R D SAtlantic multi-decadal oscillation, Brevoortia patronus, Brevoortia tyrannus, density dependence, environmental drivers, landings, length-at-age

Environmental drivers of golden tilefish (Lopholatilus chamaeleonticeps) commercial landings and catch‐per‐unit‐effort

“…The AMO has been shown to influence both primary production (Martinez et al, 2009) and ocean conditions, including winds and currents (Häkkinen et al, 2011) and storm intensity (Schofield et al, 2008). The significant influence of AMO on tilefish recruitment indicated by our study would suggest the underlying mechanism may be AMO‐induced fluctuations in primary production and/or impacts on larval transport as has been suggested for other fishes (Buchheister et al, 2016; Midway et al, 2020; Wood & Austin, 2009).…”

“…While it is likely that the NAO, in concert with the Labrador Current, played a role in the 1882 die off as indicated in previous studies (Marsh et al, 1999), golden tilefish landings do not appear to be responding solely to NAO anomalies (Fisher et al, 2014). Complicating the relationship may be the influence of the AMO which has been linked to SST and precipitation fluctuations in a unique and complicated manner along the East Coast of the U.S. (Alexander et al, 2014) and associated with population dynamics of several Northwest Atlantic fishes (Buchheister et al, 2016; Midway et al, 2020; Nye et al, 2014).…”