Climate-related meteorological and hydrological regimes and their influence on recruitment of Gulf menhaden (Brevoortia patronus) in the northern Gulf of Mexico

Abstract

Abstract-Abundances of Gulf menhaden (Brevoortia patronus) in the northern Gulf of Mexico (GOM) are heavily influenced by physical and biological processes that affect refuge and food availability. This study identified specific decadal and interannual responses in the recruitment of Gulf menhaden to local meteorological and hydrological regimes imposed by the coupling of Atlantic Multidecadal Oscillation (AMO) and North Atlantic Oscillation (NAO) phases and by El Niño Southern Oscillation (ENSO) events. Numbers of age-0 menhaden in fishery-independent surveys and numbers and proportions of Gulf menhaden ages 1-6 in commercial purse-seine landings in the northern GOM were used to investigate those responses. High postlarval abundance of Gulf menhaden (3.6/beam plankton haul) in the central region was related to the decadal wet regime associated with AMO cold and NAO positive phases. Elevated numbers of menhaden species (38.3/seine haul) in the western region were related to interannual wet regimes associated with ENSO warm and neutral events. High commercial landings of Gulf menhaden (10 million fish/vessel ton week) were related to the decadal average hydrological regime associated with AMO cold and NAO negative phases. Climate regimes may favor growth and survival by structuring offshore and inshore nursery habitats or by synchronizing release of larvae when offshore and inshore nursery conditions are favorable.

Macroscale drivers of Atlantic and Gulf Menhaden growth

“…Growth of Gulf Menhaden was positively related to AMO for both ages 1 and 2 but was negatively related to northerly wind velocity for age 1 (Wind V). AMO is a low frequency, multi‐decadal, index of climate fluctuation that is positively related to growth of Gulf Menhaden and is also positively related to recruitment strength of the Gulf Menhaden stock (Sanchez‐Rubio & Perry, ). The AMO index is associated with contrasts in precipitation patterns in the Mississippi River watershed (Enfield, Mestas‐Nuñez, & Trimble, ), and we hypothesize that this is the mechanism that results in increased annual growth rates.…”

“…Further complicating any understanding of the primary drivers of fish growth is that environmental conditions may operate and interact at different temporal and spatial scales. As an example of the difficulty disentangling factors, in the northern Gulf of Mexico the timing and magnitude of Mississippi River flow affects Gulf Menhaden Brevoortia patronus recruitment, resulting in potential annual variation that could be caused by a changing climate, short‐term variations in river flow, timing of spring thaws, broadscale environmental factors, and landings (Govoni, ; Sanchez‐Rubio & Perry, ; Vaughan, Govoni, & Shertzer, ). All of these factors could also affect growth, and the relative contribution of any one factor may be difficult to quantify.…”

Predicting ecosystem components in the Gulf of Mexico and their responses to climate variability with a dynamic Bayesian network model

“…The major categories of ecosystem components included in the analysis were climate drivers, physiochemical ecosystem pressures, lower trophic levels, recruitment deviation estimates for economically important species and population estimate for a piscivorous bird (Table 1). We include an index of the Atlantic Multidecadal Oscillation (AMO), which is influential in structuring dynamics at both ecosystem- wide and species-specific scales [26–27]. Like other modes of variability (e.g.…”

“…For the climate drivers, we used yearly averages from the monthly unsmoothed AMO index (Fig 1A) and yearly sea surface temperature (SST) values, calculated for select regions within the GoM. The mean offshore SST was found to be one of the most significant indicators in terms of the mid-1990s ecosystem reorganization, and is available at fine spatial and temporal scales likely most relevant at the scale of marine organisms [26]. A principal components analysis (derived from [25]) was used to analyze spatial patterns in SST variability across time, and formed the basis of defining three subregions (Fig 1B, 1C, 1D and 1E).…”

Ecosystem‐based forecasts of recruitment in two menhaden species

“…For menhaden, there are particular problems stemming from the fact that observational programmes responsible for measuring menhaden juveniles are largely designed around other species (e.g., striped bass). Strong dependence on stochastic environmental drivers is also a common explanation, with studies across both species identifying a wide array of processes that—at least at one time or another—affect recruitment, including longshore wind patterns (Quinlan, Blanton, Miller, & Werner, ), winter storms (Checkley, Raman, Maillet, & Mason, ) and river flow (Govoni, ; Sanchez‐Rubio & Perry, ; Vaughan, Govoni, & Shertzer, ). However, attempts to incorporate environmental information into recruitment forecasts via the traditional “environmental Ricker” (Nelson, Ingham, & Schaaf, ) have not met with much success (Myers, ).…”