Tagging of Skipjack in Hawaiian Waters 
Daniel T. Yamashita and Kenneth D. Waldroni 
The fishing of the Hawaiian skipjack 
{Katsuwoniis pelafnis) though relatively small 
if compared with the major fisheries of the 
United States, is the most important com- 
mercial fishery in the Hawaiian Islands and the 
only American fishery exploiting mid-ocean 
stocks of skipjack. Annual landings average 
about 11,000,000 pounds with a value to the 
fishermen of about one and a half million 
dollars. 
The Pacific Oceanic Fishery Investigations 
(POFI), of the U. S. Fish and Wildlife Serv- 
ice, is engaged in a skipjack tagging program 
which, it is hoped, will provide information 
that will increase the effectiveness of the local 
fishery. Tagging offers a direct means of in- 
creasing our knowledge of the growth rates, 
general migrations, and inter-island move- 
ment of the fish. In this report we will de- 
scribe the type of tags used and the results of 
our initial studies during the years 1954 
to 1956. 
A major difficulty in early tuna tagging in- 
vestigations (Rounsefell and Kask, 1945; 
Wilson, 1953) was the lack of a suitable tag. 
Alverson and Chenoweth (1951) contributed 
to the development of a better tag by their 
water tunnel experiment to determine the 
effect of flowing water on various tags at- 
tached to frozen albacore {Germo alaliinga). 
Following this work, the California Depart- 
ment of Fish and Game developed a tubular 
plastic tag (Wilson, 1953) and used it ex- 
tensively for tagging albacore, yellowfin 
{Neothimnus macropterus) , and skipjack tuna 
(Ganssle and Clemens, 1953; Blunt, 1954); 
^ Fishery Research Biologists, Pacific Oceanic Fish- 
ery Investigations, Honolulu, Hawaii. Manuscript 
received March 12, 1958. 
this tag is often called the type G or spa- 
ghetti tag. 
Prior to announcement of the successful 
California tag, POFI experimented with sev- 
eral other types, both at sea and in ponds. 
These tests involved internal tags and ex- 
ternal tags of the hook and streamer type. 
Experiments conducted in 1950 and 1952 
were either inconclusive or unpromising, so 
the California tag (Fig. 1) was adopted for use 
in Hawaiian waters from 1954 to 1956. 
APPLICATION OF THE TAGS 
The type G tag was applied in the manner 
described by Wilson (1953), with certain 
modifications. Skipjack were caught by live- 
bait fishing methods as described by June 
(1951), with 3 or 4 men in the racks. A skip- 
jack was hooked, swung up, caught by the 
fisherman, passed to a man designated as 
"holder,” the tag was attached, and the fish 
was returned to the water. With an experi- 
enced crew a skipjack could be tagged and 
returned to the water in about 20 seconds. 
Because it is difficult to handle skipjack 
without injuring them, various methods in- 
cluding canvas cradles, padded boxes, and 
electronarcosis were used in attempts to calm 
the fish. None of these was successful. Since 
it was deemed necessary to return skipjack to 
the water as rapidly as possible and since our 
efforts to quiet the fish were unsuccessful, no 
attempt was made to measure individual fish. 
Instead an estimate of the size of skipjack 
tagged was obtained by measuring fish which 
were caught and not tagged. Brock (1954) 
has shown that skipjack school by size, so it 
was believed that a reliable estimate of the 
size of tagged fish was obtained in this 
manner. 
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