Davis (1980) examined fisheries management in Everglades National Park, which involves over 
20 commonly harvested species from six ecosystems, by both commercial and recreational 
fishermen. Analysis of data on catch fishing effort, population age structure of exploited 
species, boating activity, and environmental conditions from 1958 to 1978 show three types of 
change in fishery resources. Some species increased in abundance and shifted their population 
age structure from juvenile toward adult fish, while other species declined in abundance and 
their age structure remained unchanged, including both juvenile and adults. Both general and 
specific increases in boating activity were associated with sharp declines in catch rates, 
whereas decreased boating activity since 1973 was associated with increased catch rates. 
Year-to-year variation in the availability of major game species declined, which may have been 
related to decline in the frequency of extreme climatic events and/or watershed management 
activities. No effects of harvest on finfish stocks in the Park were detected. 
6.9. Wading birds 
[The information in this section is from Powell et al. (1989b), Bancroft et at. (1994), and 
Ogden (1994).] 
Fourteen species of wading birds can be found in Florida Bay, and several of these are closely 
associated with the Bay's ecosystem. Powell et al., (1989b) report that about 50% of the great 
white herons and reddish egrets, and 90% of the roseate spoonbills found in the southeast US 
nest in Florida Bay. Such restricted populations and the high trophic levels of these species 
make wading birds vulnerable to habitat changes. These three species were virtually extirpated 
from Florida Bay from the 1800s to the mid 1930s by harvesting as a food source for humans 
and for their feathers. Once the species were protected, the populations grew quickly (Figure 9 
- 11). The number of great white herons, for example, increased from 20 specimens after the 
1935 hurricane to 800 - 900 specimens in the 1960s. The absence of pre-1800s data does not 
permit comparison of current wading bird populations with those of the pristine environment of 
the early 19th century. The wading population at that time, however, was large. Audubon, for 
example, stated in 1832 that at Sandy Key there were 'flocks of birds that covered the shelly 
beaches'. Powell et al. (1989b) state that the current population seems to be at a lower density 
than those historically present. 
Figure 9. Population growth of reddish egret in Florida Bay. [Redrawn from Powell et al. 
(1989b).] 
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