FISHERY BULLETIN: VOL. 80, NO. 3 



September, 2 through 8 October, 2 through 8 

 November, and 3 through 9 December 1979. 

 Weather permitting, surveys were conducted on 

 consecutive days in a chartered Cessna 9 172 

 aircraft at an airspeed of about 160 km/h and an 

 altitude of about 150 m. The final day of the Sep- 

 tember survey was postponed until 17 Septem- 

 ber because of adverse weather caused by Hur- 

 ricane Frederic. The flight on 6 December was 

 shortened, and flights scheduled for 7 and 8 

 December were cancelled due to inclement 

 weather. The cancellation of those flights pre- 

 vented December coverage of Charlotte Harbor 

 and associated rivers, all of the Caloosahatchee 

 and Orange Rivers, and the area from Estero 

 Bay (Lee County) south to the Broad River (Mon- 

 roe County) in ENP. The Whitewater Bay area of 

 ENP was surveyed on 9 December 1979. After 

 the July surveys, an extra survey day was added 

 to the schedule, and daily coverage was redis- 

 tributed to shorten flights in south Florida. Daily 

 surveys lasted from 2 h 25 min to 6 h 21 min 

 (x = 3 h 52 min). 



Flights usually began between 0730 and 0800 

 h. The right door of the aircraft was removed to 

 increase visibility on the 7 September flight and 

 on all flights in subsequent months. One observer 

 was seated in the right front and another in the 

 left rear. Sighting locations of all manatees and 

 dolphins were noted on charts of each earea by the 

 forward observer. Comments were dictated into a 

 cassette tape recorder, or noted directly on the 

 chart. Calves were defined as small manatees or 

 dolphins closely associating with larger animals 

 of approximately twice their size (after Irvine 

 and Campbell 1978). Dolphins or manatees with- 

 in an arbitrary distance of about 100 m of con- 

 specifics were counted as being in the same 

 "herd" or group. Use of the term "herd" to de- 

 scribe social aggregations of dolphins is well 

 established in the literature by Norris and Dohl 

 (1980), but "herds" of manatees are not known to 

 occur (Hartman 1979; Reynolds 1981). 



Flight routes were marked on maps of the en- 

 tire western Florida study area to facilitate con- 

 sistent coverage on successive surveys. The 

 routes were selected to cover probable manatee 

 habitat (Hartman footnote 3; Irvine and Camp- 



bell 1978). Survey routes generally followed the 

 2 m bottom contour. The deepwater shipping 

 channel was also surveyed in Tampa Bay. Pilots 

 used the route maps to navigate, leaving the ob- 

 servers free to scan for animals. The plane de- 

 viated from the route only to investigate sight- 

 ings and to count or photograph animals. 



Areas surveyed included 1) bays and estuaries; 

 2) the Caloosahatchee River to the Ortona Lock in 

 July and to Moore Haven on other surveys; 3) 

 canals, bayous, rivers, and creeks (>1 m deep) up 

 to 25 km inland; 4) the Intracoastal Waterway 

 (ICW); 5) coastal areas to 0.5 km offshore, or to 

 depths of about 2 m where shoals extended well 

 offshore (Pasco and Hernando Counties). 



Sighting locations on the flight record charts 

 were categorized into three habitat types: 1) off- 

 shore: the Gulf of Mexico, 2) bay-estuary: bays, 

 estuaries, and large rivers with direct access to 

 the Gulf of Mexico, and 3) marsh-river: complex 

 marsh habitats (Leatherwood and Platter 10 ), in- 

 land bays (Monroe County), and narrow rivers. 

 Using criteria from Remane and Schlieper 

 (1971), salinity at each sighting location was sub- 

 sequently classified as fresh «0.5%osalt), brack- 

 ish (0.5 to 30%osalt), or marine (>30% o salt) based 

 on available reports (E.P.A. 11 ; Wang and Raney 

 1979 12 ; U.S. Department of Commerce 1973; 

 Weinstein et al. 1977; Schmidt and Davis 

 1978 13 ). Offshore habitats were always catego- 

 rized as marine, even though salinities in some 

 areas might have been influenced by tide and 

 freshwater runoff from recent storms. Relative 

 survey effort was estimated as the percentage of 

 total flight time in each habitat and salinity type. 



Patterns of relative abundance and mean herd 

 or group size were evaluated using chi-square 

 and analysis of variance (ANOVA) procedures 

 (Sokal and Rohlf 1969). Multiple comparisons 

 among means were analyzed with Duncan's 



eluding an evaluation of tagging techniques. Report to U.S. 

 Marine Mammal Commission, Wash., D. C. National Techni- 

 cal Information Service PB 298 042. 



9 Reference to trade names does not imply endorsement by 

 the National Marine Fisheries Service, NOAA. 



10 Leatherwood, S., and M. F. Platter. 1979. Aerial assess- 

 ment of bottlenose dolphins off Alabama, Mississippi and 

 Louisiana. In D. K. Odell, D. B. Siniff, and G. H. Waring (edi- 

 tors), Tursiops truncatus assessment workshop, p. 49-86. Re- 

 port to U.S. Marine Mammal Commission, Wash., D.C. 

 National Technical Information Service PD 291 161. 



"E.P.A. Water Quality Information Storage System 

 (STQRET), 401 M. Street, SW., Wash., DC 20460. 



12 Wang,J. C.S., and E.C. Raney. 1971. Distribution and 

 fluctuations in the fish fauna of the Charlotte Harbor Estuary, 

 Florida. Charlotte Harbor Estuarine Studies. Mote Marine 

 Laboratory, 1600 City Island Park, Sarasota, FL 33577. 



"Schmidt, T. W., and G. E. Davis. 1978. A summary of 

 estuarine and marine water quality information collected in 

 Everglades National Park, Biscayne National Monument and 

 adjacent estuaries from 1879 to 1977. U.S. National Park 

 Service, South Florida Research Center, P.O. Box 279, Home- 

 stead, FL 33030. Report T-519. 



622 



