Shertzer and Williams: Reef fishes off the the southern United States 
263 
Height 
0000000 - 
OJ^cna^ 'vJOocDO 
I I I I I I I I 
Nassau grouper 
Gray snapper 
Lane snapper 
Yellowmouth grouper 
Yellowfin grouper 
Blackfin snapper 
Coney — 
Bar jack 
Schoolmaster 
Porkfish 
Black margate 
French grunt 
Sand tilefish , 
Silk snapper 1 
Jolthead porgy . 
Bluestriped grunt 
Blue runner 
Mutton snapper 
Yellowtail snapper 
Rock hind 
Red grouper 
Black grouper 
Margate 
Whitebone porgy 
Bank sea bass 
Ocean triggerfish 
Saucereye porgy 
Red hind 
Hogfish 
Longspine porgy 
Crevalle jack 
Atlantic spadefish — 
Scup 
Knobbed porgy 
White grunt 
Scamp 
Greater amberjack - 
Gag 1 
Red snapper ' 
Tomtate 1_ 
Black sea bass ' 
Red porgy 
Vermilion snapper — 
Gray triggerfish — 
Banded rudderfish 
Queen triggerfish 
Graysby ■ 
Almaco jack - 
Speckled hind 
Warsaw grouper 
Cubera snapper 
Yellowedge grouper 
Snowy grouper 
Blueline tilefish 
Figure 3 
Dendrogram from hierarchical cluster analysis of species in the headboat sector. 
Height measures similarity among species within a branch, with a value of 1.0 rep- 
resenting the lowest similarity. Scientific names are provided in the Appendix. 
represent actual relative abundances because indices 
were computed from fishery-dependent (headboat) data 
(Arreguin-Sanchez, 1996; Harley et ah, 2001). Fishery- 
independent data would have been preferable; however, 
for most species in this study, such data were of small 
sample size, short survey duration, or were nonexistent. 
We contend that the headboat data set was the best 
available for computing indices of abundance because 
of its relatively large sample size, long duration, and 
wide geographic coverage. In addition, headboat effort is 
expended generally toward a complex of species rather 
than specific stocks, and that generality minimizes any 
confounding effect of density-dependent catchability. A 
third possible reason for the negative results is that the 
population dynamics were truly out of synchrony. From 
a practical perspective, the actual reason, whether it 
stemmed from inadequate data or real dynamics, is 
of secondary concern. Foremost, positive evidence of 
