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Fishery Bulletin 1 13(4) 
Figure 1 
Map of the northern Gulf of Mexico showing the NOAA climate divisions from the western (Texas: TX6-10) and central 
(Louisiana, LA5-9; Mississippi, MS10; Alabama, AL8; and Florida, FL1) regions, the locations of stations from the U.S. 
Geological Survey near St. Francisville, Louisiana (1 blue dot seen at boundary between LAS and LA6), the NOAA National 
Data Buoy Center (2 orange dots offshore), and the Global Sea Level Observing System (2 green dots), and the sites where 
biological data were collected with seines (red dots) and beam plankton trawls (yellow dots). 
recruitment of menhaden species in the northern Gulf 
of Mexico. Meteorological and hydrological data were 
divided into 2 climate areas: central (Louisiana, Mis- 
sissippi, Alabama, and Florida panhandle) and west- 
ern (Texas). Annual values of wind momentum (north- 
south and east-west directions), SST, and Mississippi 
River nutrient influx (N:P ratio) were calculated for 
the months in which larvae of Gulf menhaden inhabit 
offshore waters. Annual values of air temperature, pre- 
cipitation, PDSI, and sea level were calculated for the 
months critical to the inshore growth and development 
of early life history stages of Gulf menhaden. Annual 
catch values were calculated by using catch data col- 
lected for the months in which juveniles and adults 
were sampled by fishery-independent and fishery-de- 
pendent methods. 
The lag in months among AMO, NAO, and ENSO 
indices and meteorological and hydrological response 
parameters in offshore waters of the northern GOM 
(wind momentum and SST), in central and western 
Gulf Coast regions (air temperature, precipitation, 
PDSI, and river flow), and in the Mississippi River nu- 
trient influx (N:P ratio) was in agreement with the lag 
reported by Sanchez-Rubio et al. (2011a). Those authors 
reported a monthly lag in hydrological responses (e.g., 
river flow input) in the northcentral GOM to changes 
in AMO, NAO, and ENSO phases. 
Decadal AMO and NAO phases and interannual ENSO events 
For this study, the phases of AMO during the period 
1948-2004 and phases of NAO and ENSO during 
1950-2004 that were described in Sanchez-Rubio et al. 
(2011a) were revised, refined, and extended through 
the use of new AMO (1899-1947), NAO (1899-1949), 
and ENSO (1895-1949) values from paleontological 
reconstruction data and new values for all indices 
(2005-2011) from observational monitoring (see Table 
1 for sources of AMO, NAO, and ENSO data). Use of 
new historical and observational data increased the 
time period of survey coverage and allowed for more 
accurate interpretation of climate descriptors. For this 
study, years classified within phases of AMO, NAO, and 
ENSO from 1962 to 2010 were considered. 
The AMO cold and warm years were defined as years 
with below-average and above-average SST across the 
North Atlantic from 0° to 70°N (Enfield et al., 2001). 
The NAO negative and positive years were defined as 
years with below-average and above-average meridi- 
onal oscillation in sea-level pressure between Iceland 
and the Azores (Hurrell and Van Loon, 1997). The 
ENSO warm and cold years were defined as years with 
above-average (>0.75°C) and below-average (< -0.75°C) 
SST in the Nino 3.4 region of the equatorial Pacific, the 
area defined by 120-170°W and from 5° S to 5°N (Rog- 
ers and Coleman, 2003). Years were considered ENSO 
neutral years when SST deviated between -0.75°C and 
0.75°C from the average conditions. 
The characterization of years within AMO phases 
described by Sanchez-Rubio et al. (2011a) were modi- 
fied in this study; years with more than 9 consecu- 
tive months of above-average or below-average condi- 
tions were characterized as AMO warm or cold years. 
As a result, the AMO warm year in 1965 (Sanchez- 
