Shertzer and Williams: Reef fishes off the the southern United States 
265 
Table 2 
Synchrony in indices of abundance of reef fishes off the southeastern United States from headboat data. Assemblages are labeled 
as Deepwater, Southern (south of Cape Canaveral, Florida), and Northern (north of Cape Canaveral, Florida). Values are correla- 
tion coefficients and proportions of coefficients (in parentheses) from «=10,000 randomizations that were smaller than the corre- 
lations presented, such that values near 1.0 indicate significance of positive coefficients and values near 0.0 indicate significance 
of negative coefficients. Asterisks note significance at the a=0.1 level after Bonferroni correction (two-tailed test). Abbreviations 
for species names are explained in the Appendix. 
Deepwater 
SnwGpr 
BluTlf 
SpkHnd 
SnwGpr 
BluTlf 
SpkHnd 
1.00 
0.45(0.96) 
1.00 
0.08(0.62) 
-0.06 (0.41) 
1.00 
Southern 
BluRun 
YtlSnp 
LanSnp 
GrySnp 
MtnSnp 
BluRun 
1.00 
-0.16 (0.21) 
-0.06 (0.38) 
-0.11 (0.28) 
-0.23 (0.11) 
YtlSnp 
— 
1.00 
0.73V1.00) 
0.78V1.00) 
-0.56V0.00) 
LanSnp 
— 
— 
1.00 
0.82V100) 
-0.65V0.00) 
GrySnp 
— 
— 
— 
1.00 
-0.64V0.00) 
MtnSnp 
— 
— 
— 
— 
1.00 
Northern 
BlckSB 
WhtGnt 
Tomtat 
GryTrf 
VrmSnp 
Gag 
BlckSB 
1.00 
-0.67V0.00) 
0.24 (0.89) 
-0.35 (0.04) 
0.47V0.99) 
0.37 (0.97) 
WhtGnt 
— 
1.00 
-0.41 (0.02) 
0.43 (0.99) 
-0.35 (0.04) 
-0.35(0.03) 
Tomtat. 
— 
— 
1.00 
0.03 (0.56) 
0.36 (0.97) 
0.19 (0.83) 
GryTrf 
— 
— 
— 
1.00 
-0.08(0.34) 
-0.14 (0.23) 
VrmSnp 
— 
— 
— 
— 
1.00 
-0.04(0.42) 
Gag 
— 
— 
— 
— 
— 
1.00 
cial data sets implies that the assemblages, although 
loosely structured, are not arbitrary. Moreover, ad- 
ditional analyses conducted as part of this study re- 
vealed assemblages that were quite similar to those 
presented. These analyses included the use of an alter- 
native transformation [logOc+1)], alternative measure 
of distance (binary dissimilarities), alternative link- 
age method with the hierarchical analysis (average 
linkage), commercial data from multiday trips (two, 
three, or four-plus days), and data by trip (i.e., trips not 
aggregated over months). 
The three clusters with the most coherence were 
deepwater, southern, and northern assemblages. The 
ranges of these assemblages likely correlate with physi- 
cal characteristics (as our chosen labels imply). Several 
of the assemblage species have been found to be linked 
through latitude, depth, and hard bottom habitat (Sed- 
berry and Van Dolah, 1984; Cuellar et al., 1996). Such 
information should be beneficial for managing assem- 
blages as units, allowing regulations to be focused on 
relevant geographic areas. 
Although the status of many stocks in the snapper- 
grouper complex is unknown, it is evident from most 
stock assessments that overfishing is occurring. In ag- 
gregate, these assessment results indicate overfishing 
of the ecosystem in general (Murawski, 2000). The av- 
erage level of overfishing and its variance, along with 
considerations of life histories and vulnerabilities, may 
indicate appropriate degrees of reduction in fishing ef- 
fort across assemblages. The use of multiple species as 
probes into ecosystem health is likely more robust than 
the use of a single indicator species. 
As single-species management loses fashion, its ideal 
replacement of full ecosystem management remains 
theoretically appealing, yet impractical given current 
data and understanding of marine ecosystems. Prog- 
ress toward ecosystem management will likely occur in 
increments (Hall and Mainprize, 2004). Where assem- 
blages exist, managing them as such offers a practicable 
step for implementing ecosystem considerations, includ- 
ing bycatch and species interrelations. Although the 
results of our study do not support the use of indicator 
species, they provide information on fish communities 
fundamental to the judicious application of assemblage 
management. 
Acknowledgments 
The authors are grateful for the support of the Southeast 
Fisheries Science Center (National Marine Fisheries 
Service), for comments from J. McGovern, M. Prager, 
C. Taylor, D. Vaughan, and anonymous reviewers, and 
for cooperation of the many commercial fishermen and 
