Variation in the Vertebral Number of the Anchovy 
(Stolephorus purpureus) in Hawaiian Waters^ 
Albert L. Tester and Robert W. Hiatt ^ 
A STUDY OF VARIATION in vertebral number 
of the nehu, Stolephorus purpureus Fowler, 
from various localities throughout the Ter- 
ritory of Hawaii, has been undertaken in 
an effort to determine whether one or several 
populations of this small but valuable bait- 
fish exist. Large quantities of nehu are caught 
each year on several different baiting grounds 
and are used in livebait fishing for the aku or 
skipjack. A recent scarcity of bait in some 
areas has posed the question of whether the 
stock is being overfished. Therefore, knowl- 
edge of whether each baiting area supports a 
separate population is of practical importance 
as well as of academic interest. 
METHODS 
Sampling 
The study is based on 18 samples taken 
mostly from the commercial catch. Although 
efforts were made to secure random samples, 
some of those submitted by the fishermen 
may include a disproportionate number of 
smaller specimens, if, as is likely, they furn- 
ished fish which died in their baitwells. How- 
ever, this would not influence the conclusions 
which have been drawn. 
Some of the samples were taken from 
catches made at night by night-light nets; 
others were taken from catches made in the 
daytime by surround nets. These methods of 
fishing have been described by June (1951). 
^Contribution No. 14, Hawaii Marine Laboratory. 
^Department of Zoology and Entomology, Uni- 
versity of Hawaii. Manuscript received October 9, 1950. 
Seven different localities are represented: 
Ala Wai Canal, Honolulu Harbor, Pearl Har- 
bor, and Kaneohe Bay on the island of Oahu; 
Kihei on the island of Maui; and Hilo Har- 
bor and Kawaihae Bay on the island of 
Hawaii (Fig. 1). Unfortunately no samples 
were obtained from other important baiting 
grounds on the islands of Kauai and Molokai. 
The samples were collected as occasion 
permitted over a period of years, from 1944 
to 1949 . There was no particular pattern as to 
time of collection or number examined. All 
samples were preserved in approximately 10 
per cent formaldehyde. 
Preparation of Vertebral Columns 
Two methods of preparing the vertebral 
columns for counting were used, the "photo- 
graphic’’ and the "direct.” In the photo- 
graphic method the fish were subjected to the 
following procedure (a modified Spalteholz- 
type preparation) : 
(1) Wash in running water for 3 hours; or 
let stand in still water for 5 hours, changing 
the water every hour. 
(2) Remove viscera, scales, and, in larger 
specimens, gills. 
(3) Bleach for 1 to 3 hours in 3 per cent 
hydrogen peroxide until lateral line and peri- 
toneum are clear. 
(4) Wash for 1 hour in running water. 
(5) Place in 1 per cent potassium hydrox- 
ide for a half hour and aspirate with water- 
vacuum pump to remove air bubbles from 
fish. 
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