628 



Fishery Bulletin 100(3) 



Mean = 63 

 SD = 60 

 n - 109 



iJjjLi 



u 



47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 



Straight carapace length (cm) 



Figure 2 



Length-frequency distribution for immature loggerhead sea turtles captured at the 

 Hutchinson Island foraging ground (1999). 



have been identified (Pella and Milner, 1987). Although 

 the source population data set represents most of the 

 major nesting colonies in the Atlantic, other nesting colo- 

 nies exist that may contribute individuals to this foraging 

 ground assemblage. For example, there are small nesting 

 loggerhead populations on the Cape Verde Islands, Cuba, 

 and on the coast of Colombia for which data are not acces- 

 sible and we have been unable to estimate their possible 

 contributions. If these nesting populations were included 

 in the analysis there is a chance that the relative contribu- 

 tions of the source populations included in our study could 

 be altered. A second major assumption is that the source 

 populations were sampled sufficiently to uncover all hap- 

 lotypes (Pella and Milner, 1987). In the case of the south 

 Florida nesting assemblage, this assumption may not 

 hold. As previously mentioned, south Florida supports the 

 largest nesting assemblage in the Atlantic Ocean and it 

 is possible that all haplotypes of the assemblage have not 

 been determined. As with the inclusion of more potential 

 source populations, there is the chance that changes in the 

 frequency and distribution of haplotypes could alter the 

 relative contributions reported in our study. We see these 

 results as a sound starting point for the eventual analysis 

 of foraging loggerhead sea turtles along the coast of the 

 eastern United States. 



The mean length of the 109 sampled turtles was 63.3 

 cm (SCL) with a standard deviation of 6.0 cm (Fig. 2). The 

 mean lengths for all haplotype groups were very similar: 

 for haplotypes A, B, C, and G (south Florida), mean length 

 was 62.9 cm (±6.2); for haplotypes I and J (Yucatan), it was 

 63.8 cm (±8.0); and for haplotypes K, M, and N (other), it 

 was 63.7 cm (±3.8). 



Discussion 



Although the estimates of percent contributions of the 

 source populations generated here are provisional (i.e. 

 more sampling of loggerhead nesting subpopulations may 

 eventually uncover previously unrecorded haplotypes), 

 they indicate that sea turtles foraging in the nearshore 

 waters of Hutchinson Island originate from at least three 

 rookeries in the Northwest Atlantic: SFL (69'7f ), Yucatan 

 (20%), and NEFL-NC ( 10%). Although the majority of ani- 

 mals appear to originate from Florida nesting beaches, the 

 maximum likelihood analysis indicates that a substantial 

 proportion of the foraging juveniles are coming from the 

 southern nesting population in the Yucatan. In addition, 

 the northern population, comprising animals nesting on 

 beaches from northeast Florida to North Carolina, also 

 contributes a smaller percentage of individuals. 



Sears et al. (1995) reported on the demographic com- 

 position of juvenile loggerhead sea turtles off Charleston, 

 South Carolina, and Norrgard and Graves ( 1995) analyzed 

 juvenile loggerhead sea turtles from Chesapeake Bay, Vir- 

 ginia. Restriction fragment length polymorphism (RFLP) 

 analysis of mtDNA was used to identify the genotype of 

 individuals in both studies. The data sets were used in con- 

 junction with a geographic survey limited to nesting loca- 

 tions in the North Atlantic Ocean and Mediterranean Sea 

 by Bowen et al. ( 1993) to estimate the composition of these 

 two areas. The estimates of contribution by nesting popula- 

 tions to these foraging areas (Table 4) appear to differ from 

 the results presented in the present study, particularly the 

 large contributions from the NEFL-NC haplotype. This 

 may either reflect real differences in haplotype composition. 



