Food of the Nehu — HiATT 
355 
area to the next, or (2) hereditary differences 
in growth rate. Unfortunately, the effect of 
fishing intensity on the population char- 
acteristics of nehu is unknown. Furthermore, 
while racial segregation, as evidenced by an 
analysis of meristic features, has been shown 
between certain areas, it has not been shown 
for others (Tester and Hiatt, in press), so no 
conclusions may be drawn concerning heredi- 
tary differences in growth rate from one area 
to the next. We do know that (1) the average 
size of fish in the commercial catch differs 
between areas but is rather consistent within 
an area, (2) the composition of the plankton 
differs between areas but is rather consistent 
within an area, and (3) large nehu exercise 
some selection and take mostly the larger 
forms among the available crustacean plank- 
ters, while small nehu seem to take the 
smaller crustacean components in about. the 
same proportion as they occur in the plank- 
ton. From these data certain implications may 
be made concerning the relation of the size 
of fish to the size of food. 
It was noted previously that a predilection 
for certain abundant, large crustacean plank- 
ters and a virtual disregard for even more 
abundant but smaller crustacean plankters 
was apparent in nehu living in Ala Wai Canal 
and Honolulu Harbor. Both these areas pro- 
duce nehu of comparatively large size. The 
medium-sized nehu of Kaneohe Bay and 
Pearl Harbor and the very small nehu of Hilo 
Bay do not exercise appreciable selectioa 
among the crustacean elements in the 
plankton. In Kaneohe Bay and in Pearl Har- 
bor large crustacean plankters are sparse in 
contrast with similar forms in Ala Wai Canal 
and Honolulu Harbor, while in Hilo Bay 
large crustaceans are absent and smaller ones 
are sparse. Thus there appears to be a positive 
relationship between the size of fish and the 
size of crustacean plankters available, and a 
relationship between the size of fish and the 
size of crustacean plankters consumed. With 
regard to the former, it appears possible that 
nehu may not exceed a certain size unless a 
sufficient quantity of food of the proper type 
and size is available. Underlying reasons for 
such a hypothesis involve nutritional de- 
mands per unit of time on the part of the fish 
and the proportional protein content of small 
versus larger crustaceans, subjects on which 
no data are available. With food organisms 
ranging from minute to large sizes, available 
in adequate amounts, it is possible that the 
growth rate of nehu is sufficiently rapid to 
provide characteristically larger fish to the 
commercial catch in certain areas. Where the 
food supply lacks organisms beyond a cer- 
tain size, growth may slacken appreciably as 
the fish becomes larger and nehu of character- 
istically smaller average size might result in 
other areas. 
TABLE 9 
Food of Nehu {Stolephorus purpureus) in Ulumoku Pond, Pearl Harbor, Oahu, Based on an Analysis 
OF 21 Stomachs 
ORGANISM 
PERCENTAGE 
FREQUENCY OF 
OCCURRENCE 
AMONG FISH 
EXAMINED 
AVERAGE 
NUMBER TAKEN 
PER FISH 
CONTAINING 
THE ITEM 
PERCENTAGE COMPOSITION 
OF FOOD ITEMS BASED 
ON TOTAL NUMBER OF 
ORGANISMS FOUND 
IN THE STOMACHS 
Copepods {Acrocalanus inermis) 
adults 
90 
83 
60 
eggs 
90 
47 
34 
Crab zoeae 
86 
6 
4 
Shrimps {Leander dehilis) 
zoeae 
10 
1 
TRACE 
megalopa 
10 
21 
2 
Barnacle larvae (cypris) 
48 
1 
TRACE 
Ghost shrimps {Leucifer faxonli) 
5 
1 
TRACE 
