Vertebral Number of Nehu — Tester and Hiatt 
69 
sampled on islands other than Oahu. No 
conclusions as to whether or not the nehu of 
the various islands mix can be drawn from 
the analysis of the vertebral material. 
DISCUSSION 
The nehu is characteristically an inshore 
fish. For the most part, it is believed to occur 
only in certain isolated localities where the 
water is relatively more turbid and less saline 
than that of the open sea. As yet, it has not 
been seen at the outer edges of the reefs dur- 
ing numerous skin-diving expeditions, nor 
has it been taken by poisoning in these 
localities. However, the fact that the fish may 
be kept alive in the baitwells of vessels for 
several days in offshore waters shows that 
they can live, for a time at least, under ocean 
conditions. Moreover, there is one report of 
nehu having been seen in quantity outside 
the reef area. Mr. Lester Zukeran, a former 
fisherman and presently skipper of the Uni- 
versity’s research vessel Salpa^ reports that, in 
the summer of 1940, large schools of nehu 
were present about a mile offshore, from 
Kaneohe Bay to Waimanalo on the wind- 
ward shore of Oahu. They were so abundant 
that they interfered with fishing, the tuna 
failing to respond to the bait when it was 
thrown overboard. As the nehu were of large 
size, larger than those caught in Kaneohe 
Bay, the fishermen advanced the theory that 
they had migrated from Kihei, Maui, where 
large fish were commonly encountered. This 
is believed to be an unusual occurrence of 
nehu in outside waters. If it were common, 
it is reasonably certain that other reports 
would have come to our attention, for there 
are many tuna fishermen operating in outside 
waters during all months of the year. On the 
basis of this information, the hypothesis 
might be advanced that an essential, discrete 
population of nehu occurs in each separate 
baiting area, but with the provision that, on 
occasion, some mixing may occur between 
the stocks of the different areas. 
The present analysis of vertebral data gives 
some support to this hypothesis, but not as 
much as might be desired for its adoption as 
a basis for regulation of the fishery. The 
existence of a separate population has been 
shown for one area only, Ala Wai Canal. For 
the others, the difference in mean vertebral 
count between localities could have arisen 
in random sampling from one statistically 
complex biological population. There is 
some indication of the presence of essentially 
separate units from the correspondence be- 
tween the order of increasing mean counts for 
localities and the order of increasingly saline 
conditions within the localities, but the latter 
were estimated and not measured. 
Although the hypothesis that essentially 
discrete units occur in each baiting area has 
not received a great deal of support from the 
analysis of vertebral material, it has not been 
disproved. More extensive sampling might 
demonstrate that there are small, but real, 
differences in mean count between localities 
and between islands, apart from the known 
heterogeneity between samples from one 
locality. Further evidence regarding the inter- 
mixture or isolation of populations, other 
than that of Ala Wai Canal, must await future 
investigations, preferably by some other 
method of study. 
REFERENCES 
Blackburn, M. 1950. A biological study of 
the anchovy, Engraulh australis (White) , in 
Australian waters. Austral. Jour. Mar. and 
Freshwater Res. 1 (1) : 3-84. 
Hart, J. L. 1937. Sexual dimorphism in 
vertebral number in the capelin, Mallotus 
villosus (Muller). Biol. Bd. Canada, Jour. 
3 (5): 417-420. 
Hubbs, C. L. 1925. Racial and seasonal varia- 
tion in the Pacific herring, California sar- 
dine and California anchovy. Calif. Fish 
and Game Comn., Fish Bui. 8: 1-23. 
June, F. C. 1951. Preliminary fisheries sur- 
vey of the Hawaiian-Line Islands area. 
