FISHERY BULLETIN: VOL. 80, NO. 3 



190 r 



180 



s 



D 

 Z 



60 



50 



40 



30 - 



20 



10 



l~l n : j—i r i~i 



123456789 



GROUP SIZE 



15 25 



Figure 2.— Group size-frequency distribution of manatees 

 sighted during aerial surveys from July through December 

 1979. 



A few manatees were consistently sighted be- 

 tween Charlotte Harbor and Tampa Bay. The 

 animals were sighted in Lemon Bay, Roberts 

 Bay, and Little Sarasota Bay, and were often 

 near the channel of the ICW. 



North of Sarasota County, manatees were pri- 

 marily sighted in rivers emptying into Tampa 

 Bay, including the Hillsborough, Alafia, Mana- 

 tee, and Little Manatee Rivers. Our observations 

 in Hillsborough and Manatee Counties may have 

 been hampered in September by cloud cover and 

 in October by turbid waters resulting from re- 

 cent flooding. 



Manatees were observed near warmwater 

 refuges described by Hartman (footnote 3) only 

 during the December flights. A total of 40 mana- 

 tees was sighted at the two warm effluents of 

 the Gibsonton Phosphate Plant in the Alfia River 

 (Hillsborough County). Eight manatees were 

 sighted in the Big Bend Power Plant effluent 

 (Hillsborough County), and a cow and calf were 

 observed just offshore of the effluent. Five mana- 

 tees were observed at the P. L. Bartow Plant 

 effluent (Pinellas County), and two manatees 

 were observed near the intake canal. A single 

 manatee was sighted in the intake canal of the 

 Anclote Power Plant (Pasco County). 



A maximum of three calves per county was 

 sighted on any survey. Total percentage of calves 

 sighted ranged from 0.9 to 4.9% on different 

 surveys. 



Caloosahatchee River, and in Estero Bay (Lee 

 County). Manatees were sighted in the Upper 

 Caloosahatchee River (Glades and Hendry Coun- 

 ties) only in November. Manatees were not 

 sighted near the warmwater refuge in the 

 Orange River, Lee County (Hartman footnote 3), 

 but the area was not surveyed in December when 

 ambient air and water temperatures were coldest. 



Bottlenose Dolphins 



Four hundred and thirty-one herds, totaling 

 1,383 bottlenose dolphins, were observed. The 

 total number of dolphins sighted increased from 

 July to November, but fluctuated in most coun- 

 ties with no obvious trends (Table 1). Sightings 

 were common in interior bays and rivers in ENP 



Table 3.— Manatee and bottlenose dolphin sightings in different habitat-types and estimated salinities. 



626 



