males is seasonal, with close correlation to the percentage of gravid females. Fewer, 
larger mature males are present during the reproductive peak, determined by fertility 
indices to occur during March, April and May. From 12 to 25 mm SL, sex ratios are 
approximately 60:40, males to females, becoming 50:50 between 25 and 26 mm SL. 
The number of males then begins a steady decline with increasing size. Brood size 
ranged from 2 to 65 embryos with an average of 13.4. G. rhizophorae becomes 
sexually inactive in late summer until the end of winter, followed by a three-month 
spring reproductive peak. A specialized courtship occurs before copulation which 
closely resembles that described for G. punctata. Hybridization with G. affinis is 
demonstrated to occur naturally in Florida, and the nature of this cross was examined. 
Fertile hybrids were described between these two subgenerically distinct species, and 
implications discussed in terms of the speciation and systematics of Gambusia. This 
study was based on collections made by various scientists over a period of decades. 
The specimens from Florida bay were collected from 1973 to 1976. 
1973 - 1976 
Odell, D. K. (1976) Distribution and abundance of marine mammals in the waters of 
Everglades National Park. Proc., First Conf. on Scientific Res. in the National Parks. R. M. 
Linn (ed.). Trans, and Proc. Ser. 5. US Department of the Interior, Washington, DC. 673-81. 
Aerial surveys were conducted from 1973 through 1976 to assess the populations of 
dolphins and Manatees in waters of the Everglades National Park. Bottlenose dolphins 
were observed in all but one of the 48 flights. Five hundred seventy three (573) dolphin 
herds were sighted totaling 1651 individuals. Mean herd size was 2.88 animals. Only 
56 of the dolphins were calves. This count may be low as the calves stay very close to 
the mother and may be difficult to observe from the air. Fifty percent of the herds 
were feeding. The distribution of the dolphin sightings were: Florida Bay, 11%; 
Whitewater Bay, 33%; Gulf of Mexico, 36%; and inland waters, 20%. Dolphins 
appeared to be less abundant in the Park during September, October and November. 
Manatees were not observed as frequently as dolphins. These animals can stay 
submerged for 20 min and only need to raise the tip of the nose to breathe so aerial 
sightings may be difficult. Three hundred two (302) manatee herds totaling 772 
individuals were sighted. Mean herd size was 2.55 animals. The distribution of the 
manatee sightings were: Florida Bay, 1%; Whitewater Bay, 46%; Gulf of Mexico, 
20%; and inland waters, 23%. The low abundance of manatees in Florida Bay may be 
shallow water or lack of freshwater to drink. 
1973 - 1976 
Schmidt, T. W. (1979) Ecological study of fishes and the water quality characteristics of 
Florida Bay, Everglades National Park, Florida. Final Rept. RSP-EVER N-36. South Florida 
Research Center, Everglades National Park, Homestead, FL. 144 pp. 
[NO COPY OF PAPER AVAILABLE. ABSTRACT FROM SCHMIDT (1991).] An ecological 
study of the fishes of Florida Bay was directed toward acquiring baseline information 
on their relative abundance by number and biomass, habitat types, and the effect of 
environmental conditions on their distribution. A total of 182,530 fishes representing 
128 species and 50 families were collected throughout Florida Bay. Their total biomass 
was 764.9 kg. An additional 21 species were identified from supplemental 
observations. In general the greatest numbers and biomass of the fishes occurred 
during the wet season (summer and fall months) whereas the lowest numbers and 
biomass occurred during the dry season (winter and spring months). The greatest 
abundance and diversity of fishes was found in western Florida Bay followed by eastern 
and central Bay regions, respectively. The sampled areas of Florida Bay was found to 
support seagrass and macroalgal communities composed primarily of Thalassia 
testudinum, Halodule wrightii, and green algae, Pencillus sp. Salinity appeared to be the 
most important factor measured affecting fish distribution. 
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