Passerotti et al: Age validation of Sphyrna mokarran 
349 
Year of formation 
Figure 2 
Bomb radiocarbon (A 14 C) values over time in two great hammerhead shark 
( Sphyrna mokarran) individuals (SM-112 and SM-114), compared with Florida 
coral and porbeagle (Lamna nasus) reference chronologies. LOESS (locally 
weighted regression) curves have been fitted to the Florida coral and porbeagle 
data series. Terminal points for SM-112 and SM-114 are bracketed to show 
years of formation for pooled growth bands included in each sample. 
Table 1 
Summary of age data and bomb radiocarbon analysis for vertebral samples taken from great hammerhead sharks ( Sphyrna 
mokarran). Sample SM-112 was male, fork length = 300 cm, aged at 42 years, and captured on 23 July 2003. Sample SM-114 
was male, fork length=276 cm, aged at 36 years, and captured on 14 January 2004. Year of formation =year of growth-band 
formation. 
Sample 
Year of formation 
Median year of formation 
Estimated age 
& 3 C 
A 14 C 
SM-112 
1961 
1961 
0 
-11.4 
18.6 
1962 
1962 
1 
-11.4 
43.9 
1963 
1963 
2 
-11.0 
58.7 
1964 
1964 
3 
-10.5 
84.4 
1965 
1965 
4 
-9.9 
71.9 
1970 
1970 
9 
-9.2 
97.7 
1993-2003 
1998 
37 
-10.7 
99.7 
SM-114 
1967 
1967 
0 
-12.0 
117.2 
1971 
1971 
4 
-12.0 
148.3 
1997-2003 
2000 
32 
-12.2 
69.8 
dated 1970 from SM-112 fell well below the curve of 
the coral chronology, whereas the most recent (pooled) 
sample from SM-112 fell more closely to the expected 
downward trajectory for Florida coral. Samples from 
SM-114 were nearly synchronous with the coral chro- 
nology extrapolated to the year 2000. Within-shark 
patterns in h 14 C accumulation were similar to those 
of the reference chronologies, confirming that car- 
bon recorded in the vertebrae is conserved through 
time. 
