Sanchez-Rubio et al.: Climate-related hydrological regimes and their effects on abundance of |uvenile Callinectes sapidus 
143 
Table 3 
Model results determined with Akaike’s information criterion (AIC) and Bayesian information criterion (BIC) used to describe 
annual variability of the weighted catch per unit of effort (CPUE = average crab catch per ten minute trawl) of juvenile blue crabs 
(■ Callinectes sapidus) in the northcentral Gulf of Mexico. 
Response Sum of 
Model 
variables 
Explanatory variables 
df 
squares 
F value 
P(>F) 
Coeff. 
AIC 
BIC 
r 2 
1 
Weighted 
North-south wind momentum 
1 
32.261 
6.8453 
0.01438 
5.477 
51.8 
0.38 
0.28 
CPUE 
North Atlantic Oscillation 
1 
12.550 
2.6629 
0.11432 
2.278 
Precipitation 
1 
23.697 
5.0282 
0.03335 
1.058 
Intercept 
5.616 
2 
North— south wind momentum 
1 
32.261 
6.3966 
0.01735 
5.049 
53.0 
0.18 
0.23 
Weighted salinity 
1 
22.277 
4.4169 
0.04471 
-0.3328 
Intercept 
6.0473 
3 
North-south wind momentum 
1 
32.261 
6.3389 
0.01781 
5.5061 
53.3 
0.46 
0.22 
Precipitation 
1 
20.992 
4.1248 
0.05185 
0.9928 
Intercept 
5.8755 
4 
North-south wind momentum 
1 
32.261 
6.3234 
0.01794 
4.7625 
53.4 
0.54 
0.22 
Palmer drought severity index 
1 
20.642 
4.0460 
0.05399 
0.5745 
Intercept 5.8365 
Climate-related hydrological regimes 
Figure 2 
Weighted catch per unit of effort (CPUE = average crab catch per 
ten-minute trawl) of juvenile blue crabs (Callinectes sapidus) 
related to the two dominant climate-related hydrological regimes 
in the northcentral Gulf of Mexico between 1973 and 1994 (AMO 
cold-NAO positive: gray bar) and 1997-2005 (AMO warm-NAO 
negative: white bar). AMO=Atlantic Multidecadal Oscillation and 
NAO=North Atlantic Oscillation. Horizontal lines for each box 
plot indicate 5 th , 25 th , 50 th (median), 75 th , and 95 th percentiles. 
suggest that the influence of salinity might be 
operating extrinsically by structuring the sur- 
rounding biotic community. Recent research 
indicates that predation affects abundance in 
the northern GOM. Studies on predator-prey 
interactions (Heck and Coen, 1995; Guillory 
and Prejean, 2001; Moksnes and Heck, 2006) 
and habitat selection and utilization (Williams 
et al., 1990; Morgan et al., 1996; Rakocinski et 
al., 2003) indicate that factors that increase or 
decrease refuge availability are also determi- 
nant in the establishment of population levels. 
Both inter- and intraspecific predation, operate 
to regulate abundance of juvenile blue crabs in 
the GOM (Guillory et al., 2001). A high diver- 
sity of predators, few predation-free refuges, 
and year round predation activity (i.e., a lack 
of seasonality in predation) all contribute to 
the high regional mortality of juvenile crabs 
(Heck and Coen, 1995). If predation is the 
primary determinant of population levels, then 
those factors that influence available refuge 
may ultimately control abundance. 
In the current study, the period of greatest 
crab abundance (climate-related hydrological 
regime I) was associated with a mean positive 
north-south wind momentum and a mean low 
value of AMO. Blue crab abundance was also 
positively correlated with the north-south 
component of wind momentum and PDSI and 
was negatively related to salinity. About 25% 
(22-28%) of the variability in blue crab abun- 
dance was explained by a north-south wind momentum 
in concert with either salinity, precipitation, or PDSI, 
or by the combination of NAO and precipitation. The 
AMO and NAO were found to be important drivers of 
climate-related features influencing long-term hydrolog- 
ical conditions across coastal Louisiana and Mississippi 
