B|orndal et a!.: Somatic growth function for immature Caretta caretta 
243 
Table 1 
Number of age classes (years) in Atlantic loggerhead sea turtle populations within the size range of 46 to 87 cm curved carapace 
length. Estimates were calculated from von Bertalanffy growth models presented in the referenced studies. Method is type of data 
(SC=skeletochronology, MR=mark-recapture, LF=length frequency); n = sample size. 
Location 
Number of 
age classes 
n 
Method 
Reference 
Chesapeake Bay 
13 
83 
SC 
Klinger and Musick, 1995 
Cumberland Island, Georgia 
IF 
25' 
SC 
Parham and Zug, 1997 
9- 
26- 
SC 
Parham and Zug, 1997 
Cape Canaveral, Florida 
29 ,J 
5D 
MR 
Schmid, 1995 
26 4 
\1 4 
MR 
Schmid, 1995 
Mosquito Lagoon, Florida 
15 
28 
MR 
Frazer and Ehrhart, 1985 
Florida, Atlantic Coast 
20 
1234 
LF 
This study 
Gulf of Mexico 
20 
570 
LF 
This study 
' Based on “1979-new” data set in which correction-factor protocol was used (Parham and Zug, 1997). 
2 Based on “1980” data set in which correction-factor protocol was used (Parham and Zug, 1997). 
3 Based on “all recaptures” data set (Schmid, 1995). 
4 Based on “contract vessel” data set (Schmid, 1995). 
could have obscured age-class modes, 
but because MULTIFAN was able to 
distinguish modes and the models fit- 
ted the data well, this procedure was 
apparently not a problem. 
The von Bertalanffy parameter es- 
timates generated by MULTIFAN for 
asymptotic length (LJ) and intrinsic 
growth rate ( K ) for the Florida At- 
lantic were L„= 118.5 ±0.7 cm and 
A"=0.044 ±0.001/yr and for the Gulf 
of Mexico were L x = 113.0 ±0.4 cm 
and A=0.051 ±0.001/yr. The maxi- 
mum CCL value recorded for logger- 
heads nesting in the southeastern 
United States is 124 cm (Dodd, 1988); 
therefore the estimates of asymptotic 
length are reasonable. 
Discussion 
Duration of the neritic lifestage 
Most loggerhead sea turtles in the 
North Atlantic recruit to neritic habi- 
tats over a size range of 46 to 64 cm 
CCL (Bjorndal et al., 2000). Size at 
recruitment will affect duration of the 
neritic lifestage. From our model, log- 
gerhead sea turtles that recruit at 46 
cm CCL will require 20 years to reach 87 cm CCL, whereas 
those that recruit at 64 cm CCL will require 13 years to 
grow to 87 cm CCL (Fig. 3). Because loggerhead sea turtles 
usually remain in neritic habitats after recruiting to these 
habitats, total duration of the neritic lifestage will include 
the years subsequent to attaining 87 cm CCL. The demo- 
graphic ramifications of this variation in size at recruit- 
ment should be evaluated. 
