McKenna: Structure and dynamics of the fishery harvest in Broward County, Florida 
123 
landings of offshore pelagics may reflect a decrease 
in availability as swordfish moved out of the fishing 
area (Hoey 8 ) or a decline in market value, or both. 
An examination of catch records showed no evidence 
that fishermen who harvest offshore pelagics had 
switched to another fishery. However, the increase 
in landings of lobsters by some fishermen who tar- 
get grouper-snappers and inshore demersals is in- 
dicative of a shift to the more valuable lobster fish- 
ery when the season opens. 
The grouping of trips into distinct clusters that 
roughly correspond to different habitats indicates a 
structure among the fishermen, based on what they 
target. The use of specific gear and fishing sites re- 
stricts the diversity of the catch. The fisherman’s 
ability to use different gear (sometimes on the same 
trip) and visit different sites is a key characteristic 
of Florida’s fisheries. Twenty-five types of gear were 
registered by Broward County fishermen in 1989. 
Such unusual combinations as longlining for sword- 
fish and pulling traps for lobster commonly occur on 
the same trip. Six hundred and ninety-eight of the 
907 fishermen registered rod-and-reel as one of the 
gear types they possessed (not necessarily used). 
Each fisherman may register more than one type of 
gear. The fishing potential of each gear is also differ- 
ent. Only 72 fishermen registered surface long lines, 
but those 72 lines had a total of 29,445 hooks. 
Florida also requires special licenses for use of cer- 
tain gear and for landing some species. Two hundred 
and eighty-two lobster (crawfish) licenses were is- 
sued to Broward County fishermen in 1989 ( 207 fish- 
ermen registered a total of 32,433 traps). Other spe- 
cial licenses included: blue crab (76), stone crab ( 123), 
shrimp (2), and purse seine (1). 
Species groups identified by the cluster analysis 
(Table 1) correspond to those that are vulnerable to 
different gear types. Species in the offshore pelagic 
group are caught in offshore surface waters with 
hook-and-line and surface long lines (Berkely et al., 
1981). Most of the common groupers and snappers 
are caught in shallow, nearshore or shelf waters with 
hook-and-line. Bait fish are found in all surface wa- 
ters and are caught with small purse seines and 
lampara nets. Lobsters and stone crabs are found 
offshore, whereas blue crabs are harvested from in- 
shore and estuarine waters. All three are caught in 
traps, but lobster are also landed with shrimp in 
trawls. By having more than one gear type, a fisher- 
man can simply re rig his vessel (and possibly work a 
Hoey, J. J. 1985. Addendum to the source document for the 
swordfish fishery management plan. Part I. Prepared by and 
available from: South Atlantic Fishery Management Council, 1 
South Park Circle, Suite 306, Charleston, SC, 132 p. 
different site) and partake of a completely different 
component of the fishery. 
The general negative associations among species 
is another indication of the selective behavior of com- 
mercial fishermen. Since the ideal catch for a fisher- 
man is a monocrop of the most valuable targeted 
species available, landed assemblages are likely to 
be as close to that ideal as possible. The catch is 
sorted and filtered such that the vessel’s hold capac- 
ity is filled with the greatest amount of the most valu- 
able species caught by the gear (Gulland, 1983). Thus, 
one would expect some trips to be monospecific, oth- 
ers to include a minimum number of other species. 
Without detailed information on discards and fish- 
erman behavior, it is difficult to determine if nega- 
tive associations represent an ecological condition 
whereby the two species avoid each other (or have 
different, but overlapping habitat requirements) or 
if they are an artifact of gear selection and fisher- 
man behavior. Most likely they are the result of a 
combination of these factors. 
The selectivity of the commercial fishing process 
and the nonrandom sampling of the natural envi- 
ronment makes it extremely difficult to use commer- 
cial landings data to gain insight into the natural 
fish community of a region. The commercial data 
provide only one component of the mortality affect- 
ing a fish community. Landings by recreational fish- 
ermen can be substantial ( Essig et al., 1991 ) but are 
often unavailable. Moreover, fish discarded at sea 
often represent the largest component of fishing 
mortality in a region (FAO, 1973); the market val- 
ues that drive the selection process are often not 
available with the landings data. Nonrandom spa- 
tial and temporal distribution of harvest can yield 
only biased estimates of fish population sizes, and 
the extent of that bias cannot be determined. 
Conclusions 
There was clear structure to the commercial fishery 
harvest in Broward County during 1989. The low 
diversity, classification of trips into habitats fished, 
and negative species associations were clear indica- 
tions of the selectivity in the system. A rich variety 
of species were landed by the fishery as a whole, but 
fishermen focused individual trips on a restricted 
subset of these species. The multispecies nature of 
the fishery and the potential for fishermen to exploit 
different components of the fishery are important 
features and should be carefully considered when 
forming management strategies. 
These commercial data tell us little about the natu- 
ral fish community from which the harvest was 
