Livingston et al.: Estimating the annual proportion of nonspawning adult Macruronus novaezelandiae 
107 
Figure 4 
Resting ovary with oocytes in the late perinucleolar stage, December 1991. (ep = early 
perinucleolar stage oocyte, lp = late perinucleolar stage oocyte (some yolk vesicles present)). 
for ages 5, 7, 8, 9, and 10 + , but age 6 (the 1986 cohort) 
and ages 1,2,3, and 4 could not be estimated because 
the strata with samples contained less than half of the 
total number of fish in the survey area. In 1993 there 
were enough data to make a reliable estimate of the 
proportion of prespawners for ages 5, 6, 8, 9, and 10 + , 
but ages 3 and 7 (again, the 1986 cohort) were unreli- 
able and ages 1, 2, and 4 could not be estimated. 
The estimates of prespawners in each age class for 
the two surveys are shown in Figure 6. Although there 
were too few samples to obtain reliable estimates for 
fish of age 4 and under, it is clear that this propor- 
tion would be small. Only 3 of 42 (7%) fish in the 
sample that were age 4 or younger were classified as 
prespawners. It is therefore likely that the ogive in- 
creases steeply below age 5 before levelling off. 
Proportion of adult fish spawning 
Figure 6 suggests that there may have been some 
increase in the proportion of prespawners up to age 
8 in 1992 but that in 1993 the numbers of pre- 
spawners did not increase after age 5. 
If we assume that any increase after age 7 is not 
significant, then the asymptotic values of the ogives 
Table 3 
Numbers of hoki classified in each histological stage com- 
pared with numbers of hoki classifed in each macroscopic 
stage (May 1993). 
Macroscopic stage 
Histological stage 
Resting 
Maturing 
Total 
Nonspawners 
450 
2 
452 
Chromatin Nucleolar 
1 
0 
1 
Perinucleolar 
449 
2 
451 
Prespawners 
449 
235 
684 
Yolk Vesicle 
154 
1 
155 
Vitellogenic 
295 
197 
492 
Ripe 
0 
37 
37 
Grand total 
899 
237 
1,136 
in Figure 6 represent the measured proportion of 
adult prespawners (p + ) in the years 1992 and 1993. 
Following a procedure identical to that above, but con- 
sidering only fish aged 7 and over, the proportion of 
adult prespawners in the survey area was estimated 
as 66% in 1992 (SE 3%) and 65% in 1993 (SE 2%). 
