Eggs and Larvae of the Nehu — Tester 
341 
TABLE 12 
Frequency Distribution of Larvae Taken by All Nets according to Length, Survey, and Sector 
(S, Southern; M, Middle; N, Northern), and Summary 
LENGTH 
CLASS 
SURVEY 1 
SURVEY 2 
SURVEY 3 
SURVEY 4 
MEAN PER CENT 
OF SURVEY 
TOTAL 
s 
M 
N 
S 
M 
N 
S 
M 
N 
s 
M 
N 
2.5 
27 
— 
— 
— 
— 
— 
8 
— 
— 
28 
26 
1 
• 7.12 
3.0 
178 
6 
1 
6 
2 
- 
11 
3 
- 
54 
123 
4 
23.35 
3.5 
63 
- 
- 
21 
4 
- 
3 
2 
- 
19 
43 
2 
10.27 
4.0 
57 
- 
- 
10 
9 
- 
- 
2 
2 
11 
9 
- 
7.29 
4.5 
54 
- 
- 
23 
3 
4 
5 
- 
- 
13 
4 
- 
6.24 
5.0 
61 
1 
- 
27 
5 
- 
3 
1 
- 
6 
2 
- 
6.81 
5.5 
73 
- 
- 
20 
11 
2 
3 
1 
2 
3 
3 
- 
7.44 
6.0 
56 
- 
- 
25 
8 
2 
9 
5 
- 
6 
1 
- 
10.03 
6.5 
50 
- 
- 
14 
12 
1 
6 
- 
- 
3 
1 
- 
6.33 
7.0 
41 
- 
- 
5 
6 
- 
1 
- 
- 
3 
1 
- 
2.94 
7.5 
43 
- 
- 
6 
8 
2 
6 
- 
- 
2 
2 
- 
5.07 
8.0 
30 
1 
- 
7 
6 
- 
4 
- 
- 
- 
1 
- 
3.56 
8.5 
9 
- 
- 
2 
2 
- 
1 
- 
- 
- 
- 
- 
0.98 
9.0 
14 
1 
- 
3 
2 
- 
- 
- 
- 
- 
- 
- 
0.95 
9.5 
4 
1 
- 
4 
1 
- 
1 
- 
- 
- 
- 
- 
0.95 
10.0 
3 
- 
- 
- 
- 
- 
- 
- 
- 
- 
- 
- 
0.10 
10.5 
- 
- 
- 
2 
- 
- 
- 
- 
- 
- 
- 
- 
0.19 
11.0 
1 
- 
- 
1 
- 
- 
- 
- 
- 
- 
1 
- 
0.19 
11.5 
1 
- 
- 
- 
- 
- 
- 
- 
- 
- 
- 
- 
0.03 
12.0 
2 
— 
— 
— 
— 
— 
— 
— 
— 
— 
— 
— 
0.06 
20.5 
- 
- 
- 
- 
1 
- 
- 
- 
- 
- 
- 
- 
0.09 
Totals* 
767 
10 
1 
176 
80 
11 
61 
14 
3 
148 
217 
7 
99.99 
* The totals do not agree with those of other tables as some larvae were damaged and could not be measured. 
with modes at 3.0, 6.0, 7.5, and possibly 
9.0 mm. 
In attempting to interpret the biological 
significance of the modes, it must be re- 
membered that the eggs hatch between 12 
midnight and 2 A.M. and that the newly 
hatched larvae are about 2.0 mm. in length. 
Since the tows were taken between 9 a.m. and 
2 P.M., it seems reasonable to assume that 
the first mode, at 3.0 mm., includes larvae 
which are about 9 to 14 hours of age, com- 
prising the 0-day group. Only a few of these, 
however, had the large yolk sac characteristic 
of larvae of this age reared in dishes. Some 
had obviously lost the yolk material when 
damaged during capture. Others, of 3.0 mm. 
and larger, appeared to have absorbed the 
yolk sac almost completely and to have ad- 
vanced in their general development to a 
stage 24 hours older, at which the mouth 
parts are forming. It seems likely, therefore, 
that the distribution represented by the first 
mode includes larvae of both the 0-day group 
(9 to 14 hours) and also the 1-day group (33 
to 38 hours). 
Once the mouth has formed and the larvae 
start feeding, more rapid growth might be 
expected. Thus the modes at 6.0, 7.5, and 
9.0 mm. may represent the 2-, 3-, and 4- day 
groups. This would indicate an absolute 
growth rate of 1.5 mm. per day. If this rate 
were maintained, the nehu would become 
initially vulnerable to the commercial fishery 
(at a length of about 23 mm.) within about 
2 weeks after hatching. If there were a de- 
celeration of growth (which is likely), it may 
still be assumed that the period between 
hatching and recruitment is short — a matter 
of weeks, rather than years as in most tem- 
perate 2 one fishes. The interpretation of the 
