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PACIFIC SCIENCE, Vol. II, October, 1948 
is voracious and that it feeds primarily on small 
fish and medium-sized plankton. He also de¬ 
scribes their feeding method, whereby they dart 
swiftly into a school of small fish and scatter 
them in the same manner as do the pelamids 
and tunas. Our observations on the feeding 
methods of the black skipjack certainly do not 
coincide with those set forth by Kishinouye. 
However, it is entirely possible, as he states, that 
the feeding habits of the black skipjack may 
vary throughout the year. Undoubtedly their 
habits vary depending upon the type of food 
available at any particular time of the year. 
Kishinouye also implies that Euthynnus yaito 
is usually a solitary fish and is not found in 
schools. Schools of this species, ranging from a 
few fish to many hundreds or even thousands of 
individuals, are often seen around the Hawaiian 
Islands throughout the year; and, during the 
summers of 1946 and 1947, very large schools 
of this species were common in the northern 
Marshalls. It is quite likely that such schools 
exist in the Marshalls throughout the year; 
except for the summer months, however, no 
observations have been made. Chapman 
{Calif. Fish and Game, 32(4): 165-170, 1946) 
states that black skipjack were present in large 
schools at Midway Island, Johnston Island, and 
Palmyra Island in the fall of 1943. Most of the 
observations reported by Kishinouye were made 
at the periphery of the range of Euthynnus 
yaito; in this region smaller schools and perhaps 
even solitary individuals would more or less be 
expected. 
The only observations on the herding of prey 
by fish other than the tuna or tuna-like fish were 
reported by Gudger {Carnegie Inst. Wash., 
Pub. 252: 75-76, 1918), who cites three in¬ 
stances involving the great barracuda, Sphyraena 
barracuda (Walbaum). In each case only a 
single barracuda was concerned; but since this 
species is rather solitary, it would have been 
rare indeed to see it engaged in a co-operative 
effort. In two cases the prey was herded into 
very shallow water; in the other instance the 
small fish remained around piles and swam 
among the rocks, not attempting to escape. In 
none of these observations on barracuda did the 
process of herding seem to be so well defined 
or so efficiently accomplished as it was in the re¬ 
lationship of the black skipjack to the scads. 
Of great significance was the fact that these skip¬ 
jack were engaged in a co-operative effort.— 
Robert W. Hiatt, Department of Zoology and 
Entomology, University of Hawaii, and Vernon 
E. Brock, Division of Fish and Game, Territorial 
Board of Agriculture and Forestry, Honolulu, 
Hawaii. Published by permission of Chief of 
Staff, Armed Forces Special Weapons Project, 
National Military Establishment. 
An Addition to the Fish Fauna of the Hawaiian Islands 
Spencer Tinker, Director of the Waikiki 
Aquarium, called the writer’s attention to a large 
and showy chaetodontid which he had added to 
the aquarium collection as a species unknown 
to him and to local fishermen. This species was 
readily identified as Pomacanthodes imperator 
(Bloch), heretofore not reported from Hawai¬ 
ian waters. P. imperator is a reef dweller char¬ 
acteristic of the Indo-Australian faunal region 
of which Hawaii stands as the northeastern 
frontier; hence, upon faunal grounds, the occur¬ 
rence of the species in Hawaii is not inexpli¬ 
cable. However, in view of the intensive shoal 
'water fisheries in the Hawaiian area together 
with the volume of ichthyological collecting and 
observing that have occurred here in the past, it 
would appear that the species is very rare in 
local waters. 
This specimen, 198 mm. in total length, was 
taken on January 10, 1948, in 15 fathoms of 
water by a trap fisherman off Ewa, Oahu. The 
fish, which was injured in the trap, died on 
January 13, 1948, and is presently preserved in 
the fish collection at the University of Hawaii 
Marine Laboratory at Waikiki. — Vernon E. 
Brock, Director, Division of Fish and Game, 
Territorial Board of Agriculture and Forestry, 
Honolulu, Hawaii. 
