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Fishery Bulletin 96(4), 1998 
Materia! and methods 
Squid collection and analysis 
Individuals were collected day and night, 20 Janu- 
ary to 14 February 1992, off the North West Slope of 
Australia, between about 12°S and 22°S (Wadley, 
1993) and 385 to 555 m. This study was composed of 
89 individuals of which 42 individuals were used for 
age analysis. Specimens were obtained from the RV 
Southern Surveyor and commercial vessels, which 
trawled with demersal gear (45-mm mesh net) on 
soft sandy substrates. 
The fresh N. hawaiiensis were identified by using 
field characters from Wadley (1990). Other omma- 
strephids were captured (Wadley, 1993) but Noto- 
todarus gouldi was absent in the area. Specimens 
were sampled at random from the range of sizes avail- 
able in the trawl catches. The squid were frozen at 
sea and subsequently defrosted in the laboratory for 
reproductive and statolith analysis. Measurements 
taken included mantle length (ML), total wet weight 
(W), testis weight for males and ovary weight and 
nidamental gland length (NGL) for females. 
Hectocotylisation of the ventral arm and presence of 
spermatophores in Needham’s sac were used as in- 
dicators of sexual maturity in males. In females, de- 
velopment of the nidamental gland and presence of 
mature oocytes in the ovaries were used as indica- 
tors of sexual maturity. 
Statolith removal and analysis 
Statoliths were removed through an incision in 
the cephalic cartilage, placed singly on microscope 
slides, and rinsed with 100% ethanol. The dried 
statoliths were mounted in thermoplastic cement 
(Crystal Bond, Jackson, 1990). Statoliths were 
taken for age analysis from 42 individuals selected 
from the full size range available. 
To observe the increment structure, statoliths 
were ground and polished, usually on both the 
anterior and posterior surfaces. The complete in- 
crement sequence was usually visible only on the 
posterior (convex) surface, which was preferred for 
routine counting. In many of the statoliths, the 
crystal structure obstructed a view of the incre- 
ments in the nuclear region of the anterior sur- 
face. Some statoliths were ground from the ante- 
rior (concave) surface through the obstructing crys- 
tals until the nucleus was revealed and all the in- 
crements could be observed (terminology accord- 
ing to Lipinski et al., 1991). 
Statoliths were viewed on a computer monitor 
with a video camera attached to a compound mi- 
croscope. Increments were counted by following the 
increment sequence with a cursor while using a hand 
counter. The number of increments on each statolith 
was counted at least three times and the mean was 
taken. Counts that varied more than 10% from the 
mean were repeated or rejected. The increments were 
similar in structure to daily statolith increments ob- 
served in other ommastrephid species (e.g. Hurley 
et al., 1985; Villanueva, 1992; Arkhipkin, 1996). 
Results 
Length-weight relationship 
Weight and length parameters were measured for 
37 males and 52 females. Males ranged in size from 
42 mm ML and 6.6 g to 176 mm and 211.7 g; females 
ranged from 48 mm ML and 5.3 g to 214 mm ML and 
381.6 g (Fig. 1). 
Increment number 
The relation between the number of statolith incre- 
ments and ML was linear for both males and females 
over the size range available, although there was 
considerable variability in the data (Fig. 2). The re- 
gression equations were 
