86 
Fishery Bulletin 1 14(1) 
Age estimate (yr) 
Figure 7 
Estimates of age-varying natural mortality (M) for wreckfish 
( Polyp/'ion americanus ) caught in the North Atlantic from 2000 
through 2011, based on the Gislason et al. (dashed line) and the 
Charnov et al. (solid line) methods. 
daily increment analysis on North Atlantic wreckfish 
to validate the first annulus; therefore, no conclusion 
can be made as to which method is correct. 
Peres and Haimovici (2004) also suggested annulus 
overlay could be a source of aging error in their study, 
with the implication being that it would cause under- 
aging of wreckfish in a population. To investigate this 
possibility, Peres and Haimovici (2004) experimented 
with different thicknesses of otolith sections, suggest- 
ing that much thinner sections (0.11-0.15 mm for 
ages greater than 40 years compared with 0.2-0.25 
mm for small fish [TL <75 cm]) were needed to clearly 
discern banding patterns in older wreckfish. Further 
research is warranted to determine whether the phase 
shift is due to regional differences in 14 C concentra- 
tions, to systematic underaging of specimens that re- 
sults from incorrect first annulus identification, to an- 
nulus overlay, or to other reasons. 
Irrespective of the observed phase shift, we validat- 
ed annual increment formation, and, having found no 
evidence of overaging in our bomb radiocarbon study 
and having identified several individuals aged over 
75 years in our relatively small sample, we are con- 
fident that wreckfish are living in excess of 75 years. 
The maximum age observed, 80 years, is approxi- 
mately twice the previously reported maximum age 
of 39 years (Vaughan et al., 2001). Our revised maxi- 
mum age estimate is consistent with findings for the 
congeneric species Hapuku (63 years; Francis et al., 
1999) and the South Atlantic stock of wreckfish (76 
years; Peres and Haimovici, 2004). The finding that 
wreckfish live twice as long as previously reported by 
Vaughan et al. (2001) can be attributed to a difference 
in aging technique. We aged wreckfish using trans- 
verse otolith sections that were 0.25-0.30 mm 
wide, and the prior study used sections that 
were 0.35-0.50 mm wide (Potts 2 ). 
The surface of an otolith from a wreckfish is 
far from uniform; there are many raised bumps 
along the surface, and edges are often serrated. 
Because of the narrow width between outer incre- 
ments along these irregularities, the same band 
may be seen along different planes when the 
otolith is sectioned at thicker widths. Inclusion 
of the same band at different planes can poten- 
tially cause a “smear,” that masks other nearby 
growth increments, resulting in the bands being 
grouped together and leading to under-estimates 
of ages. A similar argument was put forward to 
justify the use of thinner sections as reported in 
Peres and Haimovici (2004). 
The k value obtained in our study (£=0.124/ 
year, sexes combined) is approximately 4 
times the value previously reported for wreck- 
fish in the North Atlantic (k-0. 032/year and 
£=0. 028/year for sexes combined for the peri- 
ods 1995-1998 and 1988-1992; Vaughan et al., 
2001) and double that for the South Atlantic 
stock (£=0. 063/year, sexes combined; Peres and 
Haimovici, 2004). 
All to values reported for wreckfish are negative, 
and the value obtained in our study (t 0 =-4.96 years) is 
similar to the values reported for the population in the 
South Atlantic (/o=-6.30 years; Peres and Haimovici, 
2004) but very different from the to values (/q= -12.48 
years and /q= -16.56 years for the periods 1995-1998 
and 1988-1992) previously reported for North Atlantic 
wreckfish (Vaughan et al., 2001). The difference in to 
values is most likely due to the lack of smaller, younger 
fish in the samples used in the Vaughan et al. (2001) 
study. It is expected that if samples of younger (0-3 
years old) fish are available and included in an analy- 
sis, the resulting estimates of VBGM parameters would 
shift / o values closer to zero. As noted previously, if the 
phase shift observed in the bomb radiocarbon analysis 
is the result of systematic underaging of wreckfish by 
5-6 years because of issues with first annulus identi- 
fication, any such correction should result in a shift of 
to toward zero. 
The Loo values obtained in our study (L„= 1071 mm 
TL, sexes combined) were lower than those of the popu- 
lation in the South Atlantic (L oo =1210 mm TL, sexes 
combined; Peres and Haimovici, 2004) and the stock in 
the North Atlantic (Loc=1638 mm TL; Vaughan et al., 
2001). Note that the largest specimen (1340 mm TL) 
in our samples was nearly 300 mm TL smaller than 
the Loo value reported by Vaughan et al. (2001), and 
95% of all the specimens in our study were less than 
1200 mm TL. The difference in reported values be- 
tween our study and the study of the South Atlantic 
stock by Peres and Haimovici (2004) could simply be 
2 Potts, J. 2014. Personal commun. NOAA Southeast Fish- 
eries Science Center, Beaufort, NC 28516. 
