Fishery Bulletin 95( 1 ), 1997 
I 16 
Diversity was described by using the Shannon- 
Wiener Information Index ( H' ) (Shannon and Weaver, 
1949) and its component parts, richness (number of 
species) and evenness (V') (Pielou, 1977). 
H' = ~Y J Pi l °Se Pi 
V' = H'/ log e s, 
where p ; is the proportion of species i and s’ is the 
number of species in the entire community (Pielou, 
1977). In this study, the value of s* was set to the 
total number of species landed in a given month when 
calculating evenness per ticket, and to the total num- 
ber of species (76) landed over the entire year when 
calculating evenness per month. 
Heterogeneity ratios (HR) (HR actually measures 
beta diversity, which is an index of dissimilarity, 
Kobayashi, 1987) were calculated to measure the 
similarity between all pair-wise comparisons of 
monthly assemblages. All pair-wise combinations of 
assemblages were tested for significant differences 
(a=0.05) by using a Monte Carlo simulation tech- 
nique that compares the observed number of species 
common to the two assemblages of interest with that 
expected from randomly extracting two assemblages 
(each having the same number of species as one of 
the observed assemblages) from the community as a 
whole (FAUNSIM) (Raup and Crick, 1979; McKenna 
and Saila, 1991). 
A nonhierarchical cluster analysis (SAS 
FASTCLUS, SAS, 1985) was applied to classify the 
trips according to the species assemblage landed each 
month. A maximum of 3 iterations and 20 clusters 
were specified. No minimum radius was specified. 
The REPLACE = option was set to RANDOM so that 
a simple pseudorandom sample of observations was 
chosen as initial cluster seeds. The DRIFT option was 
specified to adjust cluster seeds to their cluster mean 
each time an observation was added. 
Spearman’s rank correlation analysis was per- 
formed on every pair-wise combination of monthly 
species landings, on a trip-by-trip basis, to test for 
significant associations. A Z-test was applied to de- 
termine the significance of each correlation at the 
0.01 level (Freund, 1970, p. 311-313). 
Results 
A total of 1,355,421 kg (2,981,926 pounds) of finfish 
and shellfish were landed in Broward County during 
1989 according to the 3,246 commercial fishing trips 
reported (Table 1). The monthly average was 112,840 
kg (248,247 pounds) ranging from 41,889 kg (92,156 
pounds) to 178,489 kg (392,675 pounds) (Fig. 2). 
Geography of the harvest 
Florida’s commercial fishing fleet is, in general, 
artisanal ( small boats operating near shore). In 1989, 
907 saltwater products licenses, 61 wholesale dealer 
licenses, and 408 retail dealer licenses were issued 
to residents of Broward County. Most fishermen 
worked in the waters immediately adjacent to the 
Broward County coast. The fishing area (Fig. 1) was 
reported for 76% of the trips landing fish in Broward 
County. According to those trip-tickets that included 
fishing area, fishermen harvested from areas 741 
(45%) or 744 (37%) on 82% of fishing trips. The num- 
ber of trips diminished as one moved away from the 
Broward County coast. Fish were caught from areas 
as far north as the waters off Indian River County 
(area 736), as far south and west as the Tortugas 
(area 2). Rarely, landings were reported from waters 
of Florida Bay off mainland Monroe County (area 3). 
Diversity 
Diversity of landed species was low in comparison 
with the natural diversity of this subtropical com- 
munity. A total of 76 species (or groups of species) 
were landed in Broward County in 1989. Diversity 
(H’) of the total harvest was 1.86; evenness (V') was 
0.43. Mean monthly diversity (1.88) was almost iden- 
tical to that for the total harvest (Table 2). Monthly 
evenness values varied between 0.31 and 0.62, a 
mean of 0.43. Diversity and evenness followed 
roughly sinusoidal patterns throughout the year, 
with peaks in September (H'= 2.69, V'=0.62) approxi- 
mately double the minimum value in May (H'=1.36, 
V'=0.31). Monthly richness approached 50 species 
most of the year; June (36) and July (44) had the 
lowest values, April (54) and November (55) had the 
highest values. Despite the fact that the waters off 
Broward County contained a relatively rich (at least 
76 species commercially harvested) multispecies fish 
community, as many as half of all trips in any given 
month landed only a single species. Mean alpha di- 
versity (defined here as diversity based on landings 
from a single fishing trip) was low (0.44) and showed 
little variability (Fig. 3). It was greatest in January 
and February and dropped to about 60% of those 
values for the rest of the year. Richness displayed a 
very small range (2. 5-3. 5 species per trip). 
Similarity 
Beta diversity (HR) among pair-wise comparisons of 
monthly assemblages ranged from 1.05 to 1.26 (Table 
3). The species assemblages landed in March and 
September were most similar and those landed in 
