BUTLER ET AL.: ESTIMATING LOGGERHEAD TURTLES BY TRAWL SURVEY 



loggerheads (adult males, adult females, and 

 subadults) utilize the channel at different times 

 of the year (Henwood 1987). Adult males are dom- 

 inant in April and May, adult females are most 

 abundant from May through August and 

 subadult turtles are predominant during the re- 

 mainder of the year. For this reason, direct com- 

 parisons between quarterly surveys may be inap- 

 propriate. 



It is unfortunate that the three discarded repet- 

 itive trawl experiments occurred in May and 

 June when the population was comprised primar- 

 ily of breeding adults. Low population levels at 

 this time may reflect a reduced catchability coef- 

 ficient in adult loggerhead turtles possibly associ- 

 ated with behavioral changes. The ability of log- 

 gerhead turtles to escape trawls may also be 

 enhanced during periods of high water tempera- 

 tures, but no evidence of this was noted during 

 August or November. 



Loggerhead turtle abundance in the remaining 

 four channels was low during all quarterly sur- 

 veys. These findings confirm the presence of log- 

 gerhead turtles along much of Florida's eastern 

 coastline, but do not indicate any channel areas 

 with turtle concentrations similar to Port Canav- 

 eral. It is of special interest that only Port Canav- 

 eral, a manmade habitat, harbors concentrations 

 of loggerhead turtles throughout the year and 

 particularly during winter months. 



The St. Mary's entrance to King's Bay survey 

 area was by far the largest site investigated and 

 may have been incompletely sampled relative to 

 the total area involved. This location was of par- 

 ticular interest to the U.S. Navy because of 

 planned construction of a Trident submarine base 

 in King's Bay. Although no concentrations of log- 

 gerhead turtles were noted over the course of this 

 investigation, future dredging of this channel 

 could potentially result in a situation similar to 

 Port Canaveral, with loggerhead turtles congre- 

 gating in a deepwater manmade habitat. 



ACKNOWLEDGMENTS 



Funding for this investigation was provided by 

 the U.S. Army Corps of Engineers, the U.S. Navy, 

 and the National Marine Fisheries Service. The 



statistical approach was based on recommenda- 

 tions of Al Rainosek. This manuscript benefited 

 from the critical reviews of Steve Malvestuto, 

 Ann Williams, Bill Davies, Bob Shipp, Andy 

 Kemmerer, Warren Stuntz, and Brad Brown. 



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