Jackson and Wadley: Age, growth, and reproduction of Nototodarus hawaiiensis 
785 
hawaiiensis specimens is unclear. Similar zones that 
occur in statoliths of the deepwater onychoteuthid 
Moroteuthis ingens might be related to a habitat shift 
from a pelagic to demersal environment (Jackson, 
1993b). The number of increments in the opaque zone 
was similar for the two species. No zonation was ob- 
served in any of 43 statoliths examined from 
Nototodarus sloanii in New Zealand (senior author’s 
personal observ.) which is predominantly a pelagic 
species. Nototodarus hawaiiensis adults are trawled 
day and night on the seafloor and might be demer- 
sal. Pelagic tows at discrete depths would be useful for 
establishing the ontogenetic descent in this species. 
Age and life span of 
Nototodarus hawaiiensis 
The deepwater habitat of N. hawaiiensis may pre- 
vent validation of statolith increment periodicity 
because of the difficulty of carrying out experiments 
on live individuals from this habitat. However, some 
evidence is available on the periodicity of statolith 
increments in other ommastrephids. Experimental 
maintenance with chemical markers has shown that 
statolith increments are laid down daily in the tem- 
perate north Atlantic Illex illecebrosus (Dawe et al., 
1985; Hurley et al., 1985) and in Todarodes pacificus 
in the north Pacific (Nakamura and Sakurai, 1990, 
1991). Furthermore, increment counts on successive 
cohorts suggest that statolith increments are laid 
down daily in both Illex argentinus in the south At- 
lantic (Uozumi and Shiba, 1993) and in Nototodarus 
sloanii in southern New Zealand waters (Uozumi and 
Ohara, 1993). We therefore assume that statolith 
increment periodicity is also daily in N. hawaiiensis. 
If the assumption of daily periodicity in increment 
formation for N. hawaiiensis is correct, this suggests 
that the squid matures early and has a short life span. 
The species reaches maturity in less than 200 d off 
the Australian North West Slope, considerably ear- 
lier than its conspecifics Nototodarus gouldi and N. 
sloanii in New Zealand waters, which live for about 
a year (Uozumi and Ohara; 1993, Uozumi et al., 
1995). However, specimens obtained from trawls in 
this study were smaller than the maximum size re- 
corded for N. hawaiiensis. The largest individuals 
recorded from Australia were 248 mm ML for a fe- 
male captured off the Northwest Shelf, and 215 mm 
ML for a male off southern Queensland (Dunning, 
1988b; Dunning and Forch, in press). Based on the 
regressions in Figure 2, and assuming linear growth 
throughout the life span, the total number of incre- 
ments even in these larger individuals would be less 
than 250. However, A. hawaiiensis females have been 
reported to reach 290 mm ML in the western Indian 
Ocean and 318 mm ML in the southeastern Pacific. 
In contrast, individuals of N. hawaiiensis are much 
smaller in the Hawaiian and Philippine waters, with 
maximum sizes of 180 mm and 160 mm ML, respec- 
tively (Dunning and Forch, in press). There thus 
appear to be regional differences in maximum size 
(and possibly age) attained by this species. 
On the basis of statolith analysis of A. hawaiiensis 
in Australia, this species may complete its life cycle 
in less than one year. It has a growth rate and life 
span comparable to tropical Australian shallow-wa- 
ter loliginids, which complete their life cycle in less 
than 200 d (Jackson, 1990; Jackson and Choat; 1992; 
Jackson and Yeatman 1996). Nototodarus hawaiien- 
sis spends a considerable proportion of its adult life 
in deeper, cooler waters compared with the loliginids. 
However, many oceanic squids spend a proportion of 
their early life phase in the epipelagic zone (Roper 
and Young, 1975; Vecchione, 1987; Bigelow, 1992) 
Therefore, a considerable proportion of the life span 
of A. hawaiiensis is probably spent in warmer, epi- 
pelagic waters. The youngest individual captured at 
depth in this study was 49 d, which suggests that 
perhaps the first 50 days (approximately 25% of the 
life span) might be spent in the epipelagic zone. 
Forsythe (1993) proposed a model of squid growth that 
predicted that increased temperature during a squid’s 
early growth phase can dramatically increase its growth 
rate, resulting in a much larger adult size. This model 
has recently been validated by seasonal growth data 
for Lolliguncula brevis (Jackson et al., 1997). Nototo- 
darus hawaiiensis may therefore reach a larger size 
more quickly than if it spent most of its life span in 
cooler waters at depth. 
The statolith analysis of A. hawaiiensis on the 
North West Shelf of Australia suggests a much 
shorter life span than that of other ommastrephids 
in tropical waters, e.g. Todarodes angolensis in the 
northern Benguela upwelling (Villanueva, 1992) and 
Sthenoteuthis pteropus in the tropical Atlantic 
(Arkhipkin and Mikheev, 1992) which have estimated 
life spans of around one year. 
Acknowledgments 
We thank M.C. Dunning for advice on maturity indi- 
cators in A. hawaiiensis. We are also thankful for 
comments from three anonymous reviewers. 
Literature cited 
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1993. Age, growth, stock structure and migratory rate of 
pre-spawning short-finned squid Illex argentinus based on 
