A NEW TAGGING METHOD OF DOLPHINSTOSHIO KASUYA* AND NOBUO OGURO*ABSTRACT

In order to establish a technique to tag the dolphins without disturbing ordestroying the school, tagging with bow and arrow was tried for dolphins whichcome to the bow of the ship. This method requires less skill in shooting and no
special handling of the ship. Though, in this method, more than half of thetags are wasted and the length of the time when the tag remains on the dolphin
is unknown, this method can be applied in the study of the short period movement of the schools.

INTRODUCTION

Dolphin fishing is operated at the several places on the Pacific coast of Japan.
In the northern area Phocoenoides and few other boreal species are caught with handharpoons. And in other area Stenella caeruleoalba, S. attenuata, and other severaldelphind species are caught both with hand harpoons and by driving a whole dolphinschool into a harbor.
The establishment of the tagging technique is desired to obtain the informations
on the migration and the schooling behavior of these species. Especially for thelatter purpose, tagging must be performed without destroying the school.
This experiment was intended to establish the method of tagging the dolphinsfrom a cruising vessel.
MATERIALS AND METHOD

The tags are of a type FH-69A (Floy Tag &Manufacturing, Inc., Seattle, Washington), and of the similar type used by Sergeant and Brodie (1969) for Delphinapterus
leucas, except for a clear vinyl tube which covers, in the present tags, the printed return address and the number. The size of the stainless steel head is 35 mm in lengthand 7 mm in width. The length of nylon string is 15 cm. The weight of tag is
about 3 g.
The arrow, applicator of the tag, is composed of three parts. The shaft is a
tube made of glass fiber, 36 cm in length and 7.4 mm in diameter, and furnished withno feather. The head is made of brass. Its anterior part is shaped of a flat disc
(15 mm in diameter, and 4 mm in thickness) to protect the dolphin from heavy injury,
and the posterior part is shaped of a rod (6 mm in diameter and 17 mm in length)
which is inserted into the shaft. A steel rod (70 mm in length and 3 mm in diameter)
is inserted into a hole at the center of the brass disc. This rod protrudes about
45 mm from the disc, to leave about 1.5 cm between the disc and head of the tag.

* Ocean Research Institute, University of Tokyo, Tokyo.
Sci. Rep. Whales Res. Inst.,
No. 24, 1972, 81-85.

82

KASUYA A:¥"
D OGURO

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Sci.Rψ.
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,No.2
4,1972.

DOLPHIN TAGGING

83RESULT

Preliminary experimentAs the first step of preliminary experiment, three diameters of disc of the arrow
head, 15 mm, 20 mm, and 25 mm, were tried on a carcass of Stenella caeruleoalba laidin the air. The 15 mm disc was considered to be of enough size to protect the dolphin, and other experiments were made with 15 mm disc. This tag could efficiently
penetrate into the dead dolphin sunk in a tank about 15 cm beneath the surface of thewater, when shot at the distance of 5 m and at the angle of about 45°.
Other preliminary experiments were made on a school of Stenella caeruleoalba
kept alive in Kawana harbor, and on an alive Phocoenoides truei tied to a ship. In theformer case, two dolphins which had been swimming together were tagged and thisaccompaniment was observed for 7 hours until one tag, which hit on the hard tissue
just behind the blowhole and did not penetrate enough, dropped. Another individual was tagged on the throat and penetrated sufficient depth.
In the case of Phocoenoides, when the three parts of the arrow were not fixed butloosely inserted each other, the tag penetrated under the blubber of dorsal region.

Practical experiment
The result of tagging is shown in Table 3. Two tags, nos. 3 and 4, were shot at
the bow of the research vessel Tanseimaru (257 gross ton). Her height at bow andspeed at the time of tagging were 4.5 m and 10 knot respectively. 8 tags, from no.
31 to no. 45, were shot on the whale catcher Ryuhomaru no. 3 (429 gross ton), andthe height and speed were about 6 m and 4 knot respectively. 3 tags, nos. 54, 62and 67, were shot on the research vessel Hayachinemaru (54 gross ton), and the heightand speed were 3 m and 8 knot respectively.
TABLE 1.

SOME INFORMATIONS ON TAGGED DOLPHINS
School Water.
tempersize
ature

Tag
no.

Date

Position

Species

320 Nov. '71

35°23'N, 141°ll'E

Tursiosp sp.

13

17.5

4
31
34
35
40
41
42
43
45
62
?67
54

21 Nov. '71
19 Jan. '72

34°52'N, 141 °05'E
29°35'N, 140°38'E

S. caeruleoalba

220.0

100

19.8 }

School of small dolphins,
no mother and calf2019.8Mother and calf observed214)

Mother and calf observed,,,,,,,,}

29°3l'N, 140°42'E
20°07'N, 141°1 l'E) JOO"10 Feb. ,72

39°45'N, 142°17'E

Phocoenoides truei },,14 Mar. '72

39°0l'N, 142°17'E

Sci .Rep. Whales Res. Inst.,
No. 24, 1972.

139.4

66.3

Remarks
Other schools in short distance84

KASUYA AND OGURO

21 tags were wasted to tag the 13 dolphins. The number of tags hit is 38% of
the total number of tags shot.
At present (31 March 1972) no recovery is reported.
DISCUSSION
This method of tagging is aplicable for the dolphins which come to the bow of theship without any special technics both in shooting the arrow and in handling the ship,even on the ship with high bow. But it is difficult to tag the dolphins which do notcome to the bow, and requires special technics in the shooting and in handling theship.
Even in the former species, the difficulty differs between species. Phocoenoides
swims zigzag very actively at the bow, and considered to be one of the difficult species
to tag.
According to the experiment on the Ryuhomaru no. 3, tagging was easier at thespeed of 4 knot than the cruising speed 14 knot, because the dolphin stays longer on
the surface, But the suitable speed may vary between species, because too slow speed
does not usually attract the dolphin.
The two types of arrow head were tried. In one type, the three parts of thearrow were not fixed but loosely inserted into the holes each other. This type wastried on Phocoenoides. In other type the three parts were fixed each other, and triedon other species. There is no difference between two types in the shooting. Thetagged dolphins went out of sight, in both cases, with the arrow shaft on its body.
But we suppose that the shaft will have dropped within short period. Probably,
the former type will be better to expect earlier drop of the shaft.
The efficiency of the similar tag on Delphinapterus leucas was reported by Sergeantand Brodie (1969). And it is reported that similar tag had stayed on some delphinids
for several months (Evans et al 1972).
We consider that the present tagging method will be applicable in the study ofshort period movement of the dolphins.
ACKNOWLEDGEMENTS
This experiment was possible with the cooperation of the crews of the Hayachinemaru, the Ryuhomaru no. 3, and the Tanseimaru, and with that of Kawana Fishermen's Cooperative Union. Mr. T. Masaki of The Far Seas Fisheries ResearchLaboratory cooperated in tagging on the Ryuhomaru no. 3. Mr. S. Fujino of The
Ocean Research Institute, University of Tokyo, kindly prepared the applicators ofthe tags. Prof. M. Nishiwaki gave us valuable informations on the tag. Thesepersons are acknowledged.

Sci. Rep. Whales Res. Inst.,

No. 24, 1972.

DOLPHIN TAGGING85

REFERENCES
EVANS, W. E., J. D. HALL, A. B. IRVINE, andJ. S. LEATHERWOOD, 1972. Methods for tagging small cetaceans.
Fisheries Bull., 70(1): 61-65.
NrsHIWAKI, M., M. NAKAJIMA, and T. ToBAYAMA, 1966. Preliminary experiments for dolphin marking.
Sci. Rep. Whales Res. Inst., 20: 101-107.
SERGEANT, D. E., and P. F. BRODIE, 1969. Tagging white whales in the Canadian Arctic. J. Fish. Res.
Board of Canada, 26(8): 2201-2205.

Sci. Rep. Whales Res. Inst.,

No. 24, 1972.