Drymon et al. : Factors that affect the distribution of sharks throughout the northern Gulf of Mexico 
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Table 1 
Data that we used in our analyses of shark distribution in the northern Gulf of Mexico during 2006-09. Number, 
mean size (measured as fork length [FL] in centimeters and standard error of the mean [SE] ), size range, and 
mean catch per unit of effort (CPUE), measured as sharks 100 hooks -1 h -1 , are shown for the 5 shark species 
common to both of the 2 data sets: small (Alabama and Mississippi coasts) and large (across the northern Gulf of 
Mexico). The 5 species were Atlantic Sharpnose Shark ( Rhizoprionodon terraenouae), Blacktip Shark ( Carcharhi - 
nus limbatus), Blacknose Shark (C. acronotus ), Spinner Shark (C. breuipinna), and Bull Shark (C. leucas). n= no. 
of sharks sampled. 
Species 
n 
Mean size 
±SE (cm FL) 
Range 
(cm FL) 
Mean CPUE 
±SE (sharks 100 hooks -1 h -1 ) 
Small scale 
Atlantic Sharpnose Shark 
1016 
68.8 (0.43) 
36.0-96.3 
2.88 (0.28) 
Blacktip Shark 
474 
102.7 (0.93) 
59.8-164.0 
1.34 (0.14) 
Blacknose Shark 
600 
91.1 (0.42) 
40.9-136.0 
1.70 (0.19) 
Spinner Shark 
147 
70.1 (1.86) 
49.9-165.9 
0.42 (0.06) 
Bull Shark 
40 
102.8 (6.09) 
73.0-155.5 
0.11 (0.02) 
Large scale 
Atlantic Sharpnose Shark 
2596 
73.9 (0.20) 
33.0-115.5 
4.74 (0.41) 
Blacktip Shark 
254 
111.7 (1.19) 
38.2-157.0 
0.51 (0.08) 
Blacknose Shark 
530 
85.0 (0.52) 
40.0-104.9 
0.98 (0.11) 
Spinner Shark 
158 
104.7 (2.17) 
54.0-169.0 
0.29 (0.08) 
Bull Shark 
21 
155.0 (2.77) 
131.4-176.0 
0.06 (0.01) 
Figure 3 
Results of the centered principal components analysis (PCA) on shark data from (A) small-scale and (B) large- 
scale bottom-longline surveys conducted in the northern Gulf of Mexico during 2006-09. Numbers within the 
panels correspond to the sampling blocks (1-8) and statistical zones (4-21, minus 12) of the small- and large- 
scale surveys, respectively, used in our analysis (blocks and zones are defined in Figs. 1 and 2). Filled circles 
represent shark species. The sum of the variation explained by the first (PCI) and second (PC2) principal com- 
ponents is 91.88% for small-scale survey and 87.30% for large-scale survey. The scale is shown in ovals at top 
of each panel. 
