THE JAPANESE SKIPJACK FISHERY

Marine Biological t:^' '2: •'^''

V/OODS HOLE, MASS. j

SPECIAL SCIENTIFIC REPORT: FISHERIES No. 49

UNITED STATES DEPARTMENT OF THE INTERIOR
FISH AND WILDLIFE SERVICE

Explcinstory Note

Tlie ssrios embodisc r-is^alta of in-Tstigations, nfiually of
restrict.8.1 scope, int3nded to aid ox- JiL^ect Tnan^i^-^Tnent or
utilization •DVz.ctic.sB .--n.:! as guides for adr.inistrativn or
le^iolati'/e action. It is issued in iiTiitad quantities for the
of ricia?. use of Federal, State or cooperating agencies and in
proGos^sed forn-; for econoniy and to uvoid delaj in publication.

Vfeshin^ton, D. C.
January 1951

United States Department of the "Interior
Oscar L. Chapman, Secretary
Fish and Wildlife Service
Albert M. Day, Director

Special Scientific Report - Fisheries
No. U9

THE JAPANESE SKIPJACK FISHERY

Translated from the Japanese language by

W. G. Van Campen
Pacific Oceanic Fishery Investigations

CONTENTS
The Skipjack Fishery, By lutaka L"namura 1/
Chapter I Development of the Skipjack Fishery 1

Page

Section 1 Period of the Coastal Fishery ..., , 2

Section 2 Period of the Fishery in Adjacent Waters , i^

Section 3 Pferiod of the Fishery in Distant Waters ,,, 6

Section U ft*esent Condition of the Skipjack Fishery 8

Chapter II Characteristic s of the Skip j ack , . . , 10

Section 1 Outline of the Distribution 10

Section 1 Outline of Migrations , 16

Paragraph 1 Ecology of the Skip j ack . . . o , 17

Paragraph 2 Migrations 19

Sections Bait 23

Section 4- Characteristics 25

Paragraph 1 The Skipjack's Eyes , 25

Paragraph 2 SvrLmming Characteristic s 26

ftiragraph 3 Other Characteristic s 28

Chapter III The Skipjack Fishery 29

"^ From 84i8an iCoza. loe yjxt 2i j^ Fiaher.v. Vol, 6, Fishing Section,
pp. 17-9^. Published by Dai Nippon Suisan Kai /"japan Fisheries
Assoc iation_7> Tokyo, March 5, 19^9.

Page

Section 1 Fishing Gear ,. ^ ...» .„.o.. o « .... c « ..... o » r. o o.>,. o«. . 30

Paragraph 1 Pole Fishing Gear c . . » . <> . » . . » . . . » . . . . o . . . „ . 30

Paragraph 2 Pole Fishing Bait ,« .oo «,«.....«. o o .» .o ..o o 37

Paragraph 3 Skipjack Pole Fishing Vessels o . . . « o . » . . . o . Z^0

Section 2 Fishing Methods ,.„....„.».<, o o o ».. o .» o <. = . o ....... . 45

Paragraph 1 Bases for the Fishery » o » . » « . » . » » . . « o . 4-5

Paragraph 2 Fishing Grounds and Fishing Seasons oo..... 4-6

Paragraph 3 Detection of Schools „ o . o .» o ..<.<.. »o .. c .... . 49

Paragraph 4- Catching the Fish .,o oo. o ......... c ... = ,.. . 54

Chapter IV An Examination of Skipjack Fishing Methods <,o. ........ 59

Section 1 A Critique of Pole Fishing for Skipjack ,...„.« .„, 59

Paragraph 1 Advantages and Disadvantages of Pole

feragraph 2 Plans for Improving Pole Fishing . o . . o . . . . . 60

Section 2 Net Fishing Methods for Skipjack „ o o oo .« o o . . , o . . . . 61

Paragraph 1 Attracting Skipjack with Lights „o......... 62

Paragraph 2 Purse Seining for Skipjack ., ,o.. .o. ...... . 64

The Skipjack i'^ishery

Chapter I
Development of the Skipjack Fishery

The skipjack fishery originated in ancient times and there are various
theories about its origin but no details are known c The skipjack is not to
be found among the names of fishes in Dr, Kishinouye's report of studies
based on findings in shell heaps o The fishes eaten by the people of that
period were probably limited to those which v;ere easy to catch aad did not
in all likelihood include many of the more active species-, Swift-moving
fishes like the skipjack were probably not made the object of a fishery
by the people of that time because it would be impossible for them to catch
such fisho

iVith the later intellectual improvement of the human race methods were
devised for taking the skipjackj and probably the first to be discovered
was the use of hook and lineo This development can be pictured from the
legend of Umi-no-sachi and Yamano-sachio The skipjack fishery probably
originated as the race progressed from the prehistoric period when fish
and shellfish were taken with the bare hands to the period in which they
were attracted and taken with fishing gearo Conditions in this period can
be imagined on the basis of the mention made of skipjack in the Kojiki
and the Nihon Shoki fancient annals of Japan}* The skipjack fishing poem
of Urashima of kizunoe appears in the t^anyoshUj the most ancient anthology
of Japanese poetry, and it is recorded in the Yamatohime Seiki that when
the enshrinement of the imperial ancestors was celebrated at Ise, the chief
celebrant, Yamatohime^ offered a large quantity of skipjack at the main
shrine. This seems to show at any rate that the Japanese skipjack fishery
has been carried on since rather ancient times ^ and that at that time it
was prized a;, a valuable fisho

The region in which skipjack were caught extended all along the
Pacific coast, and fairly large numbers seem to have been takeno About
twelve hundred years ago in June of the ninth year of the Tempy"o Era in
the reign of Emperor Shomu, because evil practices were rife, the Prime
Minister gave orders to the governors in the regions of Tokaij, Tozan,
Sanin, and Sanyo to take heed of the regulations on foodstuffs » The
eating of raw mackerel and scads was prohibited, but an exception was
-uade in the case of skipjack and it was permissible to eat them rawo From
this it is deduced that at that time the fish was widely used for food Eind
that it was produced in rather large quantities,, Judging from the fact
that skipjack were eaten raw in the localities mentioned above, we can infer
the following general state of affairs o In view of the transportation
situation of the time and the level of development of tecJ-iniques for pre-
serving the freshne_ss of the fish,, it appears that skipjack were taken on
the coasts of the Tc,_ai, J-ozan, Sanin and Sanyo regions and that the fish
were used to supply the demand within those regions,, The provinces men-
tioned in this connection in the Jingishiki are Shima, Suruga, Izu, Sagamij

-»

Awa, Awa /~nami_7<, Hyuga, and Kiio This was the beginning of the period
of the coastal fishery for skipjack.

Section 1 The Period of the Coastal Fishery

This period extends to end of the Edo Period, when the people were so
charmed by the flavor of the first skipjacks of spring that they composed
such poems as

Kamakura no
Umi yori ideshi
Hatsugatsuo
Mina Musashino no
Hara ni koso ire

The first skipjack which come
From the seas of Kamakura
All disappear into
The bellies of Musashino.

The first market of the year for skipjack was held on the Buddha's birthday,
which according to the old calendar was April 8th„ That is to say that in
the period of the coastal fishery the fishing season In the Kanto region
began around April 8th of the old calendar^ which means that the fishermen
waited until the skipjack migrated into the waters close to Kamakura,,
The demand for the fish was great since at that time of the year the
flavor of the skipjack was excellent and since it accorded with the spirit
of the people of Edo to treat the fish as a harbinger of springo These
facts J together with the fact that as the manufacture of dried skipjack
sticks became general the populace acquired a taste for the fishj and its
being prized by the warrior class also were all factors in the promotion
of the skipjack fishery. The coastal fishery became a profitable enter-
prise and this led tc its farther development as a peculiarly Japanese
fishery. The ful^^-ess of the development of the -loastal fishery and the
wealth of experience gained in it became the central factors in the
opening of the next period of the fishery's progress and as the fishery
spread in its own peculiar form all over the world these factors have
formed the foundations of its present state.

From the point of view of the boats used this was the era of Japanese-
style vessels, moved for the most part by man power with oars and sculls.
The progress of the skipjack fishery has been parallelled by progress in
fishing boat constrri': tiono

Let us examine the history of the development of the skipjack fishery
and of fishing vessels in the provinces. This was a period in which when
the warm waters of the Kuroshio moved north along the coast of Japan large
schools of skipjack would follow the current and migrate in close to shore.
Neither the land nor the sea had as yet been sullied by machine civiliza-
tion, the Trater was cleaf and clean, there were no man=made obstructions,
and the great schools •:! skipjack could swim about at their leisure in
search of food freely and safely. They could be taken freely in waters

2 to 6 miles off the coastj and the fishing grounds for skipjack were all
within 10 miles of the coasto

As a result of the fishing grounds' lying so near the coast the season
necessarily began when the fish appeared within the operating range of
the fishing boats and ended when they departed. Positive measures such
as following the schools were unknown and the fishery was operated
entirely on a passive basis.

The following is a sketch of developments at various places during
the period of the coastal fishery,

(1) The Makurazaki area of Kagoshima Prefecture.,

A regular skipjack fishery has been carried on in this area for about
350 yearSo Technical instruction was received from the Kii and Tosa areas
and the boats used were chiefly powered by sails and oarSo The fishing
grounds were within several miles of the coast, and the boats, which were
made of wood, were of the box-type construction peculiar to this area.
The fishing season was the earliest of any place in Japan, the catch was
stable, and a great many people depended for their living on skipjack
fishing,

(2) Kochi Prefecture area

About A50 years ago fishermen of Kumanoura in Kishu, who had taken
skipjack off Ashizuri Misaki, drifted in to Tosa and taught skipjack fish-
ing to the people of this arefio

(3) Katsuura area of Wakayama Prefecture

Skipjack fishing in Japan really started in this region and the
techniques used here have spread throughout the country. The year in which
the fishery began here is unknown, but it is prior to those cited above.
The most flourishing period in this region was from the first years of the
Meiji Era /^about 1868_7 to around 1888, the fishing being done at this
time from seven-oared Japanese=style boats. The boats were about 8 feet
wide by UO feet long, manned by a crew of 15, and propelled by seven oars.
The fishing grounds were generally 5 to 6 miles off the coast, 12 miles
at the farthest. It Tiras day fishing, the fishermen assembling at the
boat-owner's place about 1;00 a,m, to go out fishing and returning at any
time from noon to 63OO p.m. In other words they fished mainly in the
morning and one boat took from 500 to 2,000 fish per day. The season was
from the Ath to the 7th month of the old calendar and, as the local say-
ing "When the grain is the color of loquats, we must go and fish for
skipjack off Ida," shows, the fishing usually began in the Shingu and Ida
areas between April and June,

il) Shizuoka Prefectur'= area

The origin of the skipjack fishery in this area is unknown, but it
probably began before the Tempo Era / 1830_y. At that time Japanese-style

boats of about 6='foot beam were employed with crews of 15 men, and the
fishing grounds were limited to Suruga Bay,

(5) Katsuura in Chiba Prefecture

Until the end of the Meiji Era / 1911_7 Japanese- style sailing vessels
of about 8-|-=foot beam and about 4-0 feet in length were used with crews
of 16 men„ The fishing season began in the 4.th month of the old calendar j,
and the grounds were 5 to 6 miles off shore with Katsuura as the center
of the fishery „

(6) Hiraiso area in Ibaragi Prefect\ire

The fishery was started in this region about 100 years agOo Small
Japanese- style boats were used and they operated only very close to the
coasto At that time many skipjack came in to the coast and the boats used
to go out twice a day with very good successo

(7) Kesennuma area of Miyagi Prefecture

The fishery in this area got started about the first years of the
Meiji Era /around l868^o At first the fishing grounds were 3 to 6
miles off the coast and Japanese^style hand-propelled boats were used,
sailing vessels gradually coming into use latero The fishing season
was the 6th month of the old calendar o

Section 2 Period of the Fishery in Adjacent Waters

After the period of coastal fishing the skipjack fishery entered upon
the period of fishing in adjacent waterSo This development was chiefly
due to changes in the fishing vessels„ With the advance from the era of
hand or sail-powered Japanese- style boats to the era of engine=powered
vessels, the area of operation surpassed its former limits of 5 to 10
miles off shore end was enlarged to an average distance of about 4-0 miles,
taking on quits a deepsea character considering the navigational techniques
of the timeo Piloting was in its infancy and the boats operated within
the limits of the so-called ;^amadake method, that is^ using the tops of
the mount&ins for landmarks^ This era of piloting by eye was the era of
the fishery in adjacent waterSo

During the period of the coastal fishery the fishermen occupied a
passive position with regard to fishing grounds and fishing seasons, but
the advent of the period of fishing in adjacent waters gave them a certain
degree of aggressiveness and the ability to select their own fishing ground
and seasono Consequently the catch per boat far exceeded that of the
preceding period,

(1) Kagoshima area

The fishery here cha'ig'rd from a coastal to an offshore fishery about
50 years agOo At thi'^ :ime powered vessels made their appearance and
boats of from 20 to 30 tons were built, but these motor-sailers continued

to be the box-type or Kagoshima-type boats peculiar to this region. The
fishing grounds were extended to the coasts of the seven islands south of
Kagoshima /^Satsunan Shichito^, and as the fishery was directed at both
migratory fish and shoal-dwelling fish the fishing season was necessarily
lengthened, the catch was doubled, impetus was given to the production of
Satsuma dried skipjack stick, the industry was greatly developed, and
the Kagoshima skipjack fishery attained wide fame.

(2) Kochi area ■

The beginnings of the skipjack fishery in this region were in 1906
when an engine was installed in the ?Cochi Prefectural Fisheries Experiment
Station's Himejima Maru, Stimulated by the good results of this experi-
ment, the fishery flourished from 1907 to 1920. The fishing grounds were
gradually extended farther out to sea, and the season was also extended
until it began around March or April, hit its peak from April to May, and
ended in June or July.

(3) Kishu area

In 1909 the skipjack boat Sakigake Maru (10 tons) was equipped nith
an engine, and its success stimulated the construction of boats averaging
15 tons with engines of about 28 horsepower, and capable of 2 or 3 day
voyages. The season was extended, with the peak in April, May, and June,
and the catch greatly increased.

{A) Shizuoka area

In 1903 Mr, Bunshichi Maz>uo put "an engine in the Chidori Maru operat-
ing out of Shlmizu Harbor. This experiment was a failure, but it resulted
in the Installation of an engine in the Fuji Maru of the Prefectural
Fisheries Experiment Station. In 1908 an engine was installed in the first
newly-constructed '.Ve stern- style fishing vessel, and about this time
engines of 10 to 15 horsepower were installed in the old Japanese-style
boats. As a result the fishing grounds were extended from the Izu
Shichito to the Hachijojima area, the fishing season was prolonged, the
catch was increased, and the Yakizu dried skipjack stick was produced in
greater quantity and acquired a high reputation.

(5) Chiba area

At the beginning of the Taisho Era / 1912«7 a 20 horsepower engine
was installed in a sailing vessel with good results. By about 1916 many
powered vesaels were in operation and both the fishing grounds and the
fishing season had been greatly extended.

(6) Northeastern region

Around 1912 the fishing grounds were gradually being extended to
seaward, powered vessels were putting in their appearance, and the fishery
waa developing more and more. In the beginning engines of 8 to 10

horsepower were used with good results, and the summer skipjack fishing
season came to occupy a position of iraportanceo

Thus in the period of the fishery in adjacent waters mobility was
added to the elements which had developed during the period of the coastal
fishery^ Tftis was a time of preparation for the gradual shift to the era
of the fishery in distant waterSj, and great forward strides were made
within a few years" time. This period has a very important significance
because of the advancement of the techniques which have led to the present
state of development of the skipjack fishery.

Section 3 The Period of the Fishery in Distant Waters

When the engines which had been installed daring the period of fish-
ing in adjacent waters had passed through their experimental phase, they
entered upon the period of their active employment, and during the Showa
Era / 1926 to present_7 the fishery in distant waters developed. Now the
skipjack fishery took on an aggressive character, and instead of waiting
for the migrations of the fish as they had before the fishermen began
actively to seek the schools in distant seaSc, Fortunately,, because of
Japan's freedom from foreign entanglements, the fishing fleets were able
to find bases of operations in distant waters anywhere they pleased, and
there were no obstacles of any sort to the establishment of the industry.
The skipjack fishery thus entered upon its golden age„

At this time vessels began to operate from the coasts of Japan to
distant Taiwan and the South Seas, and as a result the fishing season was
freed of its natural limitations,, Year-round fishing became possible,
methods of handling and storing the catch were rapidly improveds, the
limitations on days of operation were greatly relaxed, and it became
possible to make long voyage So

At the same time scientific studies of the migrations and habits of
the skipjack irere advanced, and the methods of f|.shing, which hitherto had
been based on personal experience and observation, were rationalized, so
that anyone, even without long experience in the fishery, could engage in
it with comparative ease and a fair degree of succesSo In addition the
wide dissemination of navigational techniques and the construction of
stronger -cessels contributed to the progress of the skipjack fishery,

(1) Kag; shisna area

^ishing vessels are from 50 to 260 tons, with the average about 100
ton~. Crews number 20 to 80 menj, and the fishing grounds extend over a
radius of 2,000 miles to the South Seas, Taiwan, Celebes, and BorneOo
The main fishing grounds are from the Satsunan Shichito to the vicinity
of the Yaeyama Chain, and the fishing season is all the year rounds

(2) Kochi area

The fishing boats .n this area are comparatively small and operate 70
to 100 miles off Maroto Saki and Ashizuri Saki, The fishing season is from

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April to Augustc At this time fishing boats from this area uo not fish
very much in other areas since schools of fish are plentiful in the nearby
waters and there is no necessity of seeking distant bases elsewhere,

(3) Wakayama area

The fishing boats of this region do not fish in distant waters,
operating mainly on grounds 70 to 80 miles offshore, and consequently
most of the boats are small c They are comparatively speedy boats of 20
to 30 tons displacement, and the fishing methods used represent merely a
rationalization of those employed during the period of the fishery in
adjacent waters,

(4) Shizuoka area

The fishing boats average 25 tons, and operate actively at Torishimaj
in the Ogasawara area, off KishUj, and off Sanriku. The season is from
April tc October o

(5) Chiba area

The fishing vessels are comparatively large and fish in the Ogasawara
and Zunan areas, moving into the coastal waters thereaftero The season is
from April to September,

(6) Northeastern area

Larger boats have come into use as the fishing grounds have shifted
out to sea^ and the vessels are now of 30 to 80 tons displacement o They
operate at distances of 70 to 120 miles offshore^ and the season extends
from May to September,

In this way the pattern of operations has changed in all areas as the
potentialities of tiie vessels have increased;, a course toward further
development has been taken^ and the fishery has attained its present condi^
tion.

Section A The Present Condition of the Skipjack Fishery

The skipjack fishery, which had advanced into the era of 1he fishery in
distant waters since the beginning of the Showa Era / 1926_7j, entered with
the ou;.Dreak of the war on a period of complete stagnation. At the close
of th ■ war it was hastily started up again and in spite of the ravages
whirn war has left upon it the industry is continuing its efforts toward
reconstruction.

According to the report for June^, 194.8, of the Fisheries Bureau,
registered skipjack boats (including vessels which fish part of the time
for tuna) numbered 1,4.20 vessels totaling 60,479 tons. Published figures ■
on the 1947 catch were 11, ^^^^ tens in June and 13$, 245 tons in July,

Local peculiarities are gradually disappearing and at present all of
the fishermen share common techniqueSy only the quality of the fishing
vessels remaining as a controlling factor in the success of the fishery.
However, operations are being carried on in the face of shortages of

necessary materials and under all sorts of controls„
furthermore has many problems inherent in it,,

The skipjack fishery

The skipjack suits th
has continued through many
day. When we consider the
used during all this time,
distant past should be so
we are faced ydth the pres
the strong points of this
weaknesses.

e eating habits of the Japanese, and the fishery

vicissitudes from ancient times to the present

fact that the same method of fishing has been

we are amazed that a method originating in the

superior for taking skipjack. At the same time

sing and important problem of further improving

technique and devising ways of dealing with its

® Let us try to collect references to the skipjack from ancient

poetry.
@ Let us try to get old stories of skipjack fishing from the old men.
@ Let us try to find out where the skipjack sold in our neighborhoods

is brought from and irtiere it is caught,
@ Let us try to go and see skipjack fishing vessels and hear accounts

of the fishing.

A'
. J'

f

J A. /I •

r^

5 c ;

D

f ■'toil

F

Figure 2 Sea areas

A. Northwestern Area

B. Satsunan Area
C„ Kinan Area

D„ Zunan Area

E„ Northeastern Area

F. South Seas Area

Chapter II

Characteristics of the Skipjack

Just what kind of a fish is this skipjack, ii^ich siiits so well the
taste of tne Japanese and is so particularly prized by them?

Taxonomically, it belongs to the mackerel familyo It is rather short
and stout and only slightly flattened laterally sc that the outline of a
cross=section is nearly cvalo The snout is pointed and there are ho
scales except on the corseleto The first dorsal has 15 spines and the
second dorsal has 2 spines and 13 rays and eight finletSe The anal fin
has 2 spines and 13 rays and seven finlets,, The upper part of the body is
a dull blue and the lower part is silvery white « There are from four to
ten longitudinal dark blue stripes along the sides of the bodyo As the
fish increases in sizej their number decreases,, The fish originate
mainly in the tropics, and in the summer and autumnj they migrate along
the warm currents to distant Hokkaido o The skipjack attains a length of 2
feet, 10 inches, and a weight of aro^^nd 5 kan i Al„35_lbs. J7„ This fish
also occurs in the Atlantic and the Mediterranaais,, L Fig„ 3 follows this
page_7o

In the following discussion of the skipjack fishery, we have, for the
sake of convenience, divided the ocean into areas in accordance with the
divisions in use hitherto as shown in Figure 2„

(a) Northeastern Area (or Sanriku Area) ■=■= the area north of a line drawn
southeast from Noj°ima Saki,,

(b) Zunan Area =■= the area east of a line drawn due south from Omae Saki
and extending to the limits of the Northeastern Area^

(c) Kinan Area (Naiokaidc- Ares'! =•= the area east of a line drawn due south
from Hi Saki and extending -to the limits of the Zunan Area„

(d) SatTSunan Area — the area east of a line drawn from Noma Saki to Fuki
Kaku (Taiwan) and extending to the Kinan Area„

(e) South Seas Area ■=- the area sotrfch of the latitude of Anpin Anchorage in
Taiwan o

(f) Northwestern Area -•= the area west of the Satsunan Area. Figo 2 -= Sea
Areas,

Section 1 Outline of the Distribution

lo Skipjack of Japan

The skipjack which come into Japanese waters come north from the South
Seas in the warm rraters of the Kuroshio or Japan Currento The northern
equatorial currentc, str- ...ig the Philippines, turns northward and passes
along the east coast oi Taiwan and the islands of Okinawa into the adjacent

10

^0^

30" 1

20°

v.! lull i-i-i..i.>.i-

Figure 3 Warm and coid currents
warm currents
d> cold currents

1. warrr Kuroshio current

2. water of low chlorinity from the Yellow Sea
3o Tsushima warm current

A. North Korean cold ctirrent

5. East Korean warm current

6. Tsushima warm current

7. Kuroshio warm current

8. Kuroshio counter -current

9. Soya warm current

lOo Kuroshio branch current

11. Oyashio cold current

12. Oyashio undercurrent

13. line of the front

1^. main current of the Kuroshio

15. Kuroshio counter-current

16. subtropical line of convergence

17. vortex

18. Northern Equatorial Current

11

waters of Japaric In the spring and summer j, riorthward=f lowing branches
stem off from it at various points, and the skipjack which appear in the
waters off Japan are cai'ried by these warm currentSc Beginning in the
Kagoshima region, they appear successively farther north and finally
reach the waters off the southern KurileSo As the cold current of the
Oyashio becomes stronger in September and October, the fish move southward
and return to the South Seas, but in places like the Okinawa, Kagoshima,
Zunan Shoto, and Ogasawara areas, where the warmest parts of the water
masses of the warm current systems flow over shoals, they divide into the
shpal skipjack, which make the shoals and their vicinities such good
fishing grounds, and the deepsea schools which congregate and move in
accordance with the developments of the main warm current system. The
shoal skipjack schools are present the year round j, while the deepsea
schools appear periodically„

2, Skipjack of Taiwan

The skipjack fishery of Taiwan 7»as started by Japanese in 1909= At
first, the operations veve carried on between the SenVaku Is„ on the north
and Kasho lo and Kotosho on the south and as far east as the waters off
Yaeyama„ Since that time, the form of the fishery has gradually been
improved and vessels from Kirun,, SuOj Karenko, Taito, and Takao have been
operating at great distances from shore. The schools are densely distributed,
and both schools of mature fish and schools of small skipjack are seen, An
indication of the density in which the fish occur is provided by the figures
on the aatch, vrfiich were 491,260 kan in 123Us, 2SU,!^,2k kan in 1935, and
A0-i,15^ kan in

*iich were 491,260 kan in 1934.si
1936„ Z 1 l£au 8 8/27"lbs„_7

There is a limit to the demand for Taiwan skipjack and this operates
to control the catch naturally ^, however, the fish are present in dense
concentrations throughout the yearo

3o Philippine Islands

(1) Batan S^.^^ait to seas east of Luzon =•- This area is traversed by
the ascending Tiain stream of the Kuroshio and skipjack schools occur there,
but we have no detailed knowledge of them as yet„

(2) Samar vicinity ■=«> In this area, there are bays and outlying islands
where sardines, mackerel, and mackerel-scad occur, and large schools of
skipjack which feed on these fishes concentrate densely between Samar and
the Hiraban Is„

(3) Southern Mindanao =- Dense schools are always seen from the
vicinity of Zamboanga to the eastern part of the Gulf of Davaoo Skipjack
are also found in the western waters between Zamboanga and Panay I„

(4) West coast of Mindoro I„, Manila Bay — In this area, dense
schools are seen 2-3 miles off shore, and many schools of Auxis thazard
and small skipjack also o-- :' here.

12

The waters adjacent to the Philippine Is„ are the original home of
the skipjack schools which migrate to Japano Schools of all types are
universally distributed throughout the area and the fishing season is all
year round, but the peak season is from Octobdr to January, when schools
of "island skipjack" which migrate close in to the coast are fished,

U. South Sea Islands

The South Sea Islands area is in the deep part of the Pacific Ocean,
and from the Carolines group in the low latitudes, it stretches intermit-
tently east and west for about 2,000 miles. At the center, the Marianas
chain runs northward, and the Marshalls form the eastern limit where they
extend for 700 miles north and south. Among these archipelagoes, the North
Pacific Equatorial Current and the Equatorial Countercurrent flow in
complicated patterns, and migratory fishes of the surface waters are
distributed everywhere. Accordingly, skipjack schools may be seen through-
out the area at all seasons of the year. / Insert Fig, U.J

The schools in this area are the source of the schools which migrate
into Japanese waters, and it may be said that the fluctuations of the
skipjack in these waters control the Japanese fishery,

5. Borneo, Celebes (English Territory)

The skipjack schools in Borneo waters come so extraordinarily close to
shore that they are taken with a type of weir called a keiron. The fish
are universally distributed throughout these waters. In the Celebes
area, the fishery is centered around Menado, Ternate, and Sangi I,, and
dense schools are widely distributed,

6. Halraahera, Sangi Is, (Netherlands East Indies)

Halmahera, Talaud I,, Sangi Is, The skipjack schools which occur
between these islands ar« large, and the fish range in size from 2 kan
£16.5 lbs._7 to 160 morame / 21,2 oz„_7,

7. Ambon I, (Malacca Is.) /"Moluccas ?_7

Skipjack schools come in close to the coasts and are widely dis-
tributed in the waters east and west of this island.

8. Australian area

The fish are distributed from southern Queensland to northeastern
Tasmania and St. Helen's I,, with the waters off Victoria as the center.
The fish also migrate into the waters off New Zealand and Lord Howe I.
They are from 1.4 to 7,3 kilograms in weight, with schools of four-year
old fish weighing 2,7 to A= 5 kilograms making up 8056 of the pooulation.
This is similar to tjje make-uo of the schools on our Sanriku /^North-
ea8tern_/ grounds, / Fig, 5.J7

9. California Coast to Mexican Coast

S.k-L.; 7 Bast ;■. '* *>■• ■iB«a ■«>«>»«■■■■■■■■ ■•:■■,■■■ I ■•••IVSI ■■!■ ■■■■■■■■■■■tl

ll<ai ■ aaai^ .'■■tiiii>i«ia«aia«i>iiaiaiiiaiiaiiiiiiiiiii»iiaBHi(aii
viaaaisBaa laaiai

Figure 4- Outline of skipjack distribution

seascnaj.

year-rotmd

....

u

Is?!

■*

f

0'

'it-,

Figure 5 Chart of the distribution of skipjack
fishing grounds (1937)

Legend showing the catch within each degree of latitude
and lonsiitude

IvViVj

1,000 - 10,000 fish
10,000 - 100,000 fish
mo, 000 - 1,000,000 fish
1,000,000 - 2,000,000 fish

A. Satsunan Area

L. Kinan Area

C. Izu Is. Area

D. Ggasnwara Area

E. Southern part of t^o Northeastern Area foff Tokiwn and Nojlmazaki)

F. Northern part of the Northeesterr Area (off Sanriku)

15

Schools of fish are present in these waters, where the^- are known as
" sukiipju jyakku . "

Thus the skipjack is distributed throughout a wide area of the
Pacific centering on the Equator, and although there ars seasonal dif-
ferences in density, they occur in these waters at all times. Beginning
in the latter part of February, detached schools pass the Nansei Shoto
and appear in the Satsunan area, while other schools appear from the
fferianas to the Ogasawara and Zunan areaSo In mid-summer, they migrate
into the Sanribj area, but in the autumn, they turn southward and disappear,
leaving no skipjack population in those waters^ TtiO fact that the dis-
tribution of skipjack in Japanese waters is, for the most partj related
to this one pattern of migration, has been the reason for the development
of the peculiarly Japanese method of fishing and has set the stage for
the skipjack fishery »

Section 2 Outline of Migrations

The general terra "skipjack" (_ katsuo / includes four species, the
tine skipjack / magatsuo /, the sumagatsuo / Euthynnus XSit£=yj "^^^
hagatsuo / Sarda orientalis /^ / A-gxis thazard~77 These are all tropical
fish which always live in sea areas which have high water temperatures.
They migrate into Japanese waters witn the Kuroshio in the summer.

(1) Sumagat suo (yaito) (watanabe) / Euthynnus yaito /

This skipjack is without longitudinal black stripes on the sides and
has several black spots below the pectoral fin. It characteristically
likes to live in the swift currents off promontories „ A coast-dwelling
fish, it prefers to stay close to islets, reefs, banks, and shoalSo While
it does inhabit swift currents, it avoids the heart of the current and
swims in ■che compai*atively slack water„ The fish characteristically chooses
a place for its nest and stays there, spotting with its keen eyes the
crustaceans, squid., and small fish which come drifting by and catching them
for food. It v;i" '. sometimes pursue its prey up toward the sur-face, but
usually returns -go its nest without going very far. In the dim light of
morning and evening these fish leave their nests and forming small schools
leap about en the surface. They rarely migrate out into the open sea and
even when moving from island to island they usually do not rise to the
surface layers. For these reasons they are unsuitable as the object of a
skipjack fishery, and they seldom migrate north of Choshi„

(2) Ha j;atsuo (sujigatsuo) (kit sune gat suo ) (hosan) / Sarda orientalis /

This is a fish of the offshore waters and generally swims close to
land at moderate depths.. They migrate into Japanese waters in small schools.
On their way north they are taken in set nets at places where the current
passes close to shore or at promontories, or when they chase young anchovies
into the bays. They ordinarily live close to land and rarely go out into
the open sea. They take dead biit as well as live bait. They also migrate
north in the Japan Sea, The dorsal portion of the body has many fine
longitudinal stripes, and the teeth are long and sharp.

16

(3) Sodakatauo 'mandara ) (sabota) (rosoku) ^uxis auoT"

There are two species of s'odaka.tsuo„ the maruso'dakatsuo ^uxis meruT
and the hir as'gdrtkat s uo _^'axis hira^yo Both like high temperatures and live
in the Kuroshio^ The marustrdakatsuo is a coastal fish^ prefers the sv/ift
currents around promontories ^ and comes into the bays in schoolo. They
cone north on the Pacific coast as far as Shiriya Misaki in Aomori
Prefecture and also enter the Japan Sea„ They use their caudal fins to
maintain their position in swift currents and cl*7-erly capture food vfhich
comes drifting down to therao At morning and evening and in cloudy weather
they sometimes leave the swift currents in search of food and school at the
surf ac 3c

The hiraso'daka.tsuo has the body more flattened laterally than the
preceding specieSs and is more of a pelagic fisho It lives around islands
and promontories s and its nattire is much like that of the sumagatsuoo They
do not fora large schools p but sometimes mingle with the true skipjacks and
in the summer they swim into the waters of the Sanriku area Northeastern
are^o Both speoies are warm v/ater fish and from their migrations it is
possible to judge the fluctuations in the Kuroshioo Around the autumn
equinox the schools which have been migrating north turn southward againo
Because of their structure these fish d'Alm in a straight linej their bodies
are torpedo-shaped^ They cannot make short turns and they are lacking in
buoyancyo They swim strongly and continuously and have finally become
adapted to living in currents so that their resting places are limited
to places which have swift currents „ They always live in clear water and
are very sensitive to any intrusion of freshwater running off from the
lando This species has wavy markings on the baok„ the snout is short,
and the eye is located far forward

Paragraph 1 Ecology of the True Skipjack

The true skipjack ^Satsuwonus pelamisJ7 is the most pelagic of the
skipjacks o It r^-ms continually in schools out at sea and performs great
periodic migra*' iS north to the limits of the OyashiOo The skipjack
fishery in Japanese waters has grown up in dependence upon this species o

Ip Spawr 1 ( areas of the true skipjack

The skipjack ''s spawning grounds are in areas of suitable warm water
where ■'-here is plenty of food for the development of the young fisho They
spe->m, <4nd develop in the southern waters^ and when they reach their prime,
th';- become aware of the instincts proper to the skipjack and start on
t.' '- r long mieration north. In the spring and sunmer they pass through
J»-panese waters and about the time of the autumn equinox they return to the
southern seaso In this fashion they continue for many years to migrate
north and souths When they reach old age and no longer have the strength
and spirit to go norths some cf them find a suitable place along the path
of migration and '-ake up their residence on a reef or shoal^ becominp; the
so-called "shoal skipjacV". ^dle others leave the migratory schools^?-"
the migration begins ■• ;.heir lives quietly in the Sorith S»-

17

In this fashion the skipjack spawn and grow up nea" the islands and
reefs in tropical waters. These waters are south of 24-° North Latitude,
and their surface tempera tuxes are above 20° „ It appears that the skip-
jack schools make their permanent homes there and pass the winter there.
Within this area they spawn principally at places close to islands and
reefs. Besides those which spawn in the South Seas, skipjack with ripe
eggs are also taken in the Okinawa and Ogasawara areas. It appears that
some skipjack also spawn in those waters. In short, the spawning grounds
of the skipjack extend over a rather wide area with the center of spawning
activity in the South Seas.

2, Development of the Skipjack

(1) The small skipjack stage (weight 3OO-4.OO momme / 39.7-53 o%J, 1-2
years old)

The juvenile fish are slender and thin^ They like to leap about on
the surface of the water. They eat mainly schlzopods, amohlpods, larval
decapods, and small anchovies. The island-dwelling schools will not
come to chum-bait and they are still very timid so that when a ^---cssel
approaches them they tend to submerge suddenly. Once they get out into
the open sea and enter upon the pattern of migration, however, they
gradually come to take the bait better and better. The schools of
descending skipjack returning south after the equinox are not skillful
in the competition for food and they are liable to have empty bellies,
which makes them take the bait very well»

Note; "Descending skipjack" are those which are returning south in the
fall after their northward migration, "Water pushing /mizuoshi7" is a
term used to describe the turbulence of the surface where a school is
feeding. IVhen they sight the prey, the whole school deploys in a line
of foragers and advances through the school of bait with the fish
showing their dorsal fins above the surface. The turbulence caused
by their tails gives rise to long continuous ripples on the surface
which make the area readily distinguishable from, the surrounding
waters.

(2) The luedimn skipjack stage (weight 600-800 momrne / 4. 96-6. 62 lbs^7>
age 3 to 4- years)

These fish are the main element in the skipjack schools which
migrate into Japanese waters. Their bodies are perfectly fusiformo
They are strongly migratory and rather than take up residence on a shoal
or around an island and eat crustaceans, they prefer to swim swiftly
-n the open sea hionting schizopods, small fishes, and squid. If they
do become attached to a shoal, they do not remain there long. They form
large groups of schools and swim through the surface v/aters in orderly
and disciplined fashion searching for food. They generally take the
bait well. They have already become adept st mizuoshi, and have learned
to herd bait and to accompany sharks and whales. At times they also
follow floating logs for thousands of miles of leisurely migration.
Note: The term "b.: ling /^c dok 0 auk-or i7" is used to describe the
action of the 3kij..^.aCK o:,nool in surrcunding a school of small sardines

18

and driving them into a tight mass irtiile greedily feedine around the
edgeSo Skipjack schools sometimes accompany kambeizame £ a species of
shark_/ and Sferdine mhaleSo

(3) The large skipjack stage (over 1^000 momme £8,28 lbs„_7 weight, 6 to
8 years old)

In this stage of development the body depth increases greatly in
relation to the lengthy the fish becomes stouter, and its movements become
slower. Its food consists of squid, crustaceans, and miscellaneous fish.
The fish generally move to the reefs of outlying islands and become
deficient in schooling instinct with a tendency to remain in small groups
at "fish nests^o Until they attain a weight of about 2,000 momme (_ 16,56
lbSo_7 they retain some of their migratory tendencies, but old fish over
that weight do not migrate and remain all the year round permanently
resident at the fish reefs of the low latitudes^ Or they may wander
around the open sea together with the albacore and come to live in waters
as cold as IS'-'Co They have a strong tendency to become what is commonly
called dekiuwo / "adventitious fish"_7 and generally keep to the lower
depthSc rising to hunt food only at certain tides or in the dim light of
morning and evening „

Notes Dekiuwo are fish which are attracted to the surface by chum-bait
or trolling lures.

Paragraph 2 Migrations

It is instinctive with the skipjack schools of the southern seas to
migrate regularly into Japanese waters in the spring and summer of each
yearo That iSj while instinctively migrating in search of food they
enter the waters adjacent to Japan, but viewed objectively the migration
is controlled by the currents in the waters vriiich the fish inhabito As
shown in Fig, 3^ the Northern Equatorial Current runs from east to west
the year round in the vicinity of 5 = 10° north latitude^ In the waters
adjacent to "ie Philippines it changes from a westerly to a northerly
current^ flo-/3 along the east coast of Taiwan, continues north along the
Okinaws chain, ^and impinges upon the coasts of Japan beginning with
southern KyushUo From the middle of March, when the Kuroshio is at its
height, a part of the fish which live within the Equatorial Current
fcllc'.7 it and are naturally brought into the adjacent waters of Japan,

If we were to classify skipjack schools from the point of view of
their migrations, it is assumed that the classification would be as
■^ollowss

(a) Schools which spend their whole lives in the tropical seas south of
23° north latitude,

(b) Schools which make a great circular migration in the northern Equatorial
Current when it is at its height in the spring and summer,

(c) Schools which r.ove north and south in the Kuroshio,

19

It is, of course, difficult to make a hard and fast distinction between
these three systems and they appear to fluctuate with natural changes in
the oceanographic eondition,3c The schools in system (a) are shoal=fish or
island~fish with a limited range of movement^ and they have a tendency to
stay in one place„ Systems (b) and (c) compidse the so-called migratory
stockc Their range of movement is broad, and in the course of their great
migrations they respond to variations in objective factors such as currents,
water temperatures, character of the sea water, food, and so fortho They
may adopt -various patterns of migration such as taking on tendencies
similar to those of system (a) and remaining throughout the year on reefs
and shoals or around islands in the Satsunan and Zunan areas, or turning
south midway in the migratory path of system (c) and failing to reach the
Northeastern areao The schools of system (b) are the main element in the
skipjack of Japanese waters and the presence or absence of these fish
determines the year to year success of the skipjack fishery,

1, The make=-ap of the skipjack population in Japanese waters

Investigations in all areas have revealed that the fish which are
taken in Japanese waters are mainly 4- to 5 years old and that the peak
seasons come ©very four yearSo

Skipjack are classified by weight j those above 1 kan / 8„27 lbSo_7
being called large skipjack, those from 500 to 1,000 momme /"/!tol3 to 8„27
lbSo_/ medium skipjack, and those below 500 momme small skipjack,. Investi-
gations in various areas shcv? some variation from year to year, but the
overall picture is generally as follows.

(1) Satsunan area

Schools of small skipjack appear aro-and March and are most numerous
from April to August o They make up about 50^ of the skipjack schools which
appear in this area„ and also s.:::count for the greatest part of the catch„
The schools of medir.."! skipjack are mingled with the schools of small fish
in March and reac' uheir greatest abundance in April and May after which
time they decline in numbers„ They reappear again in August and September,
but in this area they form the smallest element in the skipjack population
and in the catch, being only 20^ of the total. Schools of large fish
appear and are taken in the greatest numbers from April to Augusts They
form 30^ of the total catch in this area„ Thus in this area schools of
ycung skipjack are the most important, followed in order by old and
middle-i -;ed fish, which are thought to be shual-dwelling schools,

(2) Xirian area

This area is in the path of migration of the schools and the length
of time they remain in the area is extremely snort „ From the latter part
of March to the middle of May the number of schools which appear and the
catch ratios are extraordinarily small in comparison with other areas.
Small fish (60%) make up the greater part of the population, followed by
medium fish (40%), and almost no large fish appear in the area.

20

(3) Zunan area

Schools of small skipjack increase in numbers progressively from
April on and reach their peak around July after which time they gradually
decrease o In this area schools of small fish make up 35^ of the total,,
Medium fish appear in these waters at the same time as the small fish and
for a tim.e comprise 305^ of all schools. They increase until about July
and thereafter decrease to 55%^ Schools of large skipjack come in from
May to July and form about 10^ of all schools. Note; It is thought that
actually the ratio of schools of large fish should be increased somevihat
because few fishermen fish these schoolSo

(a) Northeastern area

The schools of small skipjack appear in this area in May and remain
until around September, but their number gradually diminshes„ They make
up 5% of the schools in the area. It is thought that during this period
quite a number of them grow large enough to enter the medium skipjack
category. Medium skipjack along 'with small skipjack make up the bulk of
the fish in this area, and they gradually increase until they reach their
peak in June and July after vjhich they decreaseo In these waters they
comprise 75'^ of all schools^ Schools of large fish are still very scarce
in May and gradually increase from July to September, but these are thought
to include fish which grew into the large category in these waters as well
as fish which were large when they entered the area.

To summarize the facts which have been given above for each of the
several areas, the skipjack schools which enter Japanese waters are
principally medium fishj these occupying 60% of the total „ In the North-
eastern and Zunan areas they are remarkably abundant, while in the Kinan
and Satsunan areas the schools of small fish predominate, forming 30$ of
all schools. Large fish are comparatively abundant in the Satsunan area,
but they form only about 10% of the total population. Table 2 shows the
distribution of ohe total skipjack population by areas.

Table

2

Area

1937

1938

1939

Northeastern

66%

62$

59$

Zunan

11$

13$

10$

Kinan

13$

10$

20$

Satsunan

10$

15$

11$

2, fiJigration routes of the skipjack schools

The migrations of the skipjack are controlled by the instincts peculiar
to the fish and by tho condition of the ocean currents. There is one great
migration, as described abovej, but it takes place along the following
routes,

21

(a) Along the Northern Equatorial Currant past the RiilippineSy Taiwan, and
Okinawa to the Satsunan area and thence gradually northward„

(b) From the South Seas area to the Zunan area along the northerly warm
current of the-Kuroshio which originates in the waters near the Bonins
in the spring.

(c) Northv/ard between the Northern Equatorial Current and the northerly
warm current of the Ogasawara region to the vicinity of the Kinan
reefs in the Kinan area (30° 10 « North, 136^ 4-5" East) „

These three are assumed to be the routes of migrationo These schools
of skipjack show a tendency to concentrate gradually in the Northeastern
area as the power of the Kuroshio increases from May to Julyo In the latter
part of April and the early part of May they congregate in a radius of
150 to 300 miles southeast of Nojima Saki (Chiba Pref ecture) „ Then these
schools move to the northeast and proceed north as the water temperatures
rise„ Every year in the middle and iaxter parts of July they reach the
area 150 to 200 miles east of Klnkazan (Miyagi Prefecture), Further
northward movement of the schools is barred by the pressure of tne O^faShio,
and they remain for s comparatively long time in these waterSo In
September they reach the northern limit of their migration which, depend-
ing on the year 5 may be as far north as the waters adjacent to the
Kuriles, that is, the vicinity of Etorcfu I„ and Shikotan I, Thereafter
as the Oyashio increases in strength the schools turn southward and
move south comparatively far out to sea, over 300 miles off shore, re-
turning to their native South Seas by way of the waters of the Zunan area.

In the Amami Oshxma region of the Satsunan area, the schools appear
around the early part of February and are most numerous from the end of
February to around Julyo After that time they gradually decrease in
numbers and disappear about December „ Most of the schools in this area
come up from the south and remain in the area» Some of them take up
residence around tlie reefs and become the so-called "sedentary fish''^
some part of thea eontisaue north, and the rest return to the south in the
autumn„

The schools which appear in the Kinan area are most numerous around
May, their numbers dimini':ihing remarkably in the latter part of June,
Possibly they move north into the Northeastern area. The schools of the
Zunan area put in their appearance first in the vicinity of Torishima and
are mos*. numerous in May and June, Thereafter they divide into schools
which migrate north into the Northeastern area and schools which remain
from s-ummer to autumn in this area,, A number of schools returning south-
ward from the Sanriku area are also seen in the Kinan area during October
and November o

3, Conditions iriiich regulate the migrations of the skipjack schools

The migrations of thi^ skiDJack schools are premised upon the strength
or weakness of the Kuro";.i.Oo The iiTater temperatures in the Kuroshio begin
slowly to rise in early February and reach their maximum around July and

22

early August o After that time they gradually fall„ This rise and fall in
the water temperature is a necessary condition for the migration of the
skipjackc Wien the temperature of the Kuroshic changes in this regular
fashion, many schools inhabit its waters arid the period of their stay in
Japanese waters is prolongedo When„ on the other hand, the temperature
rises and falls irregularly or changes abruptly, the migrations of the
schools also become irregular^ and although many schools may be seen in
certain localities, the migration as a whole often turns out to be of a
low volume o

On the whole the factor which controls the migrations of the schools
is the temperature of the depth at which the fish liveo Favorable
temperatures of the surface water are within the range of 19° to 26^ Co
There is naturally some variation depending on the area, the range in the
northern part of the Northeastern area being 20 - 21°, that in the southern
part of the same area 22-23^? Zunan area 23-25'^, Satsunan area 24-26 „ The
migrations are predicated on the regular appearance of the usual tempera-
ture for the season in each of the areas, the water colorj, chemical com-
pcsitionj and so forth being incidental conditionSo

Section 3 Bait

In skipjack fishing the first thing to be taken into consideration
is the choice of a bait^ The use of a suitable bait is the most vital
factor in this fishery. As set forth in the preceding pageSj, the skipjack
is hatched and grows up in the South Seas and somes north on a migration
in search of food. In general when fishes from the South Seas go north,
they tend to seek foods which resemble those to which they are accustomed
in the South. This probably is instinctive in the fish„ The following
is an account of the foods found in the South Seas area.

(a) tarekuchi iwashi /"probably Engraulis heterolobus Ruppell_7 "■" The
body is flattened laterally.. The fisn occur in shallows where the water
is less than cz.e fathom deep on coasts where fresh water enters the sea
and where msv;..^ove trees grow densely in the vicinity. They school
together with the maiwashlo

(b) maiwashi /"may be Harengula moluccensis Bleeker_/-= About 3o6 inches
in length, they concentrate in the shade of trees along the shore„ Those
which occur near shore are particularly flattened laterally^ The oba
iwashi. which are 4„8 to 6o0 inches long, are not seen along the shore but
o'.oar in deep water. They differ somewhat from the maiwashi of Japan „

<^) urume iwashi == They do appear along the shore but are found in waters
of about 10 fathoms depth. The head resembles that of the barracuda, the
body is silvery, and the eye is large. The flesh is white and soft, and
the fish are hard to keep aliv8o

(<^) shirotare iwashi =- The shape of the head resembles that of the
tarekuchi iwashi^ but the fish is white and has one golden stripe along
its sideSo This spe^iies is not seen near shore in shallow places^ It
forms dense schools and is suitable for use as bait. The scales are thin

23

and easily come off. The body is soft and weakn and although it is all
right for chuiimning baitj it is not suitable for baiting hooks and ±s dif-=
fic'^lt to kesp a live o

(e) kiniKo xg-agni =-= Like tne maijyg.sfai in loi'm wa-on small scales and a
pointed head„ Those about 2o4 inches 3.n length come in close to shore in
about two or three feet of watero They are suitable for bait, but cannot
be taken in large quantitieSo

(f) shirozaMo iroshij akazako im,shi -= The ghiroaakg iwg-shi is white and
is from „96 ineh to 1<,2 = 2o4^ inches in length,, The aK:ag-ako iwashi is
pale red and usaally about 2oU inches longo Both are rather translucent
so that their flesh and skeleton can be seen through their skino They
live around ooral reefs in depths ii-p to 7 or 8 fathomSj 'and some out of
the holes ia the reef at night to search for food^

(g) baka r '-- -■- - == This is the p..-i.ac.\pal baitfisih in Saipaa waters„ It
attatn? 5 ._ of froTr; 1„2 to Q..,L IncheSo

(h; :u^.^£& <== This fish ife^^fru.c^ts untr young of tne niraiwashi oi v^apafl.
Its body is long and slender and it 13 abundant around Saipano

(i) hiraa;i i ■=- The you.ng of tn« mgc^^^^^-^ £ probably Trachurops crnmenopthalma
(Bl0'Shj_/o _It is ?iiu2h larger than the shiira, seven fish weighing about
ICC ^mif / 13o27 ounces^^''^ They ar.a very good as bait for medium and large
skipjack „

(j) MEgSil. ■=" Similar in size to the hiraajij. these fish are suitable as
bait for medium and large sklpjaek,,

(k; akaro^jrfe / probably Cas_ssi^o c.hjyj.02,c.ma (Kuhl & Hass)^/"" About 3 inches
long. They occur "" ''-rge sofeoolSj, are suitable for bait., and are easily
kept alive o

(l) .saner= ^ ^. . |.vS t? caesic.ixu oi apogonid^/ -■ = These fish .iongregate
on the botr,.- ..atside of the reef in depths of 12 to 16 fathoms and are
about 1 xies longo

Ic -idition to^the abovf. Jkipjaek's diet inclndes the aohige

a kind of itoyori £ Euthiyopterang, 3pc?_/9 o^san, takabe £ a pomadasid?^/,
shlmaBr^-ro guru gin „ tobugoroj kibinaggo dogoro iwashi /Ateggij^ia. valenciennesii
Bleek ■_' ?_7, and otherSo

These small fish provide food for the skipjack schools in the South
Se.dS area,, and as a result<, tb.e older they become the more accustomed they
are to these types of food,, Consequently even during their migrations they
necessarily seek the same kicSs r..f fo-o.do This gives some indication as
to the bait to select for skipjack fishing ir« Japanese waterSc

When schools of ""■■- '■-":■:« yftsldh hB.\>- ^^r.^wa up on this sort of food

come into Japans >« ■ whax. sort of things do they eat? If we

examine the f the skipjack which are taken, we can

answer the qu

24-

Sardines, anchovies^ mackerel, mackerel-scadSj myctophids, flying-
fish, squid, Ryilkyii squid, shrimp, spotted shrimp, larval crabs,
schizopods, and amphipodSo Quite a few fish are found to have completely
empty stomachs.

The state of the balance between the total population of skipjack in
Japanese waters and the available supply of natural food as well as the
factors which led to the establishment of the skipjack fishery are believed
to be implied in these facts.

The following deductions can also be made from a consideration of
the skipjack's food habits. Schools which feed on such things as mackerel,
maokerel=scad, spotted shrim.p, larval crabs, and amphipods, all of which
are of a coastal character, are composed of "sedentary fish" or fish which
have stayed temporarily around islands, reefs, and shoals„ The schools
which feed on pelagic forms such as flyingfish, squid, and schizopods are
those which are accustomed to svTimming in the open sea„ Schools of fish
which have empty stomachs can be assumed to be pelagic schools which have
not been able to find food before being taken„

Section 4 Characteristics of the Skipjack

Paragraph 1 The Skipjack's Eyes

According to Mr, Shigeo Yamamoto's report of his researches, "The
study of the refraction characteristics and accommodation mechanism of
the eye of the skipjack reveals the following facts. Judging from the
fact that the crystalline body in the eye of the fish is almost spherical,
it has been said in the past that the fish are near-sighted, but this study
has revealed that they are on the contrary far-sighted, very much so in
facto This has been established in the case of the skipjack, tuna, sea-
bass, and striped marlin„ If we measure the crystalline body's refraction
of parallel rays of light in the air, we find that it has a very short
focal distance of only 0<,4- inm, however, if we measure it for the skipjack in the
water with apiece of glass fastened behind it f'], we find that it has a
long focal distance of 15 mm, differing markedly from the visual line of
about 6 vtimo This places the focal point about 7 mm behind the retina of
the eje, and means that the eye is far=sighted„ This is thought to be
the condition when the eye is at rest, and it is assumed that it is so
constructed as to be capable of even stronger far-sight. The fish can
se& clearly at least 30 or 35 feet ahead, but of course it is impossible
to see as far in the water as in the air, no matter how far-sighted it
nay be, because the water contains more fine particles than the air and
the sun's rays are weaker in the water^ The eye muscles of the skipjack,
like those of terrestrial mammals, include the superior direct, inferior
direct, inferior oblique, external direct, and internal direct muscles,
but great differences are apparent in their size and points of insertion.
These muscles net only move the eyeball forward and backward and up and
down, but they appear also to contribute to the adjustment of the vision ,,.
A statement of the c '.Irsicns bcssd on the results of the study would
indicate that the sicip jack does not have very good vision obliquely to
the rear. When relaxed or at rest,, all of the eye muscles are resting,

25

the eyeball is flush with the spindle-shaped aurfaee of the nead (at an
acute angle to the center line of the body) , and both eyes are directed .
somewhat forwar3o At such times it can be said that ths eyes are a bit
more far-sighted than when the vision is directed to the sides or obliquely
to the rear,. This means that when fishing it is ineffective to throw
bait close to the sides of the body^ The superior- direct muscle and the
s-jperior oblique muscle are stronger than the corresponding inferior
muscles, and because of this the skipjack's eye can more easily be turned
upward than downwardo Consequently it is thought that the fish cannot
see very w^ll below the level of its bodyo Since the -apper forward edge
and the lower rear edge of the eye socket have eoncavitisSj it seems that
i/isual power is especially great to the upper front and the lower rear„
The field in which rather far vision is possible lies from obliquely
ahead to straight ahead of the hodjo and vision must be best along a
prologation of the center axis of the bodyo Because the pupil of the
skipjack's eye is large and ellipsoid in shape its field of vision both
ahead and to the rear is ma^h greater than that of the human eye„ When
the skipjack strongly contracts the internal direct Tirascie, the eyeball
is directed obliquely forwardp the line of sight is shortened, the convexity
of the crystalline body is somewhat deor-?ased, and the vision becw-mss
remarkably far-sightedo Depending on the clarity of the water^ it
appears that the vision extends to upwards of 60 feet. As a result of
having such powers of sight the skipjack can swim at speeds of 60 to 70
knots per hour without colliding with anything and can swim about in large
schoolSo They can also, relying pi5.rtly on their instincts, surround large
schools of sardineSo It is entirely due to its excellent eyesight that the
skipjack can be readily taken by fishermeUo That is to say,, it is because
the skipjack is far=sighted that it can see the chumming bait from a
distance^ and when it comes in close in order to taks the bait, it becomes
unable to distinguish the artificial lures from the live bait. If
artificial lures are used when the fish are being attracted from a distance,
they are ineffective because the fish have good enough vision to distin-
g-dish themo Such rores should be used after the skipjack have been
brought in closer The practice of spraying water while fishing with pole
and line gear ie Jso based on this characteristic of the skipjack,,"
Fishing methods, should be thoroughly thought out in order to take advan-
tage of the skipjack's far-sightednesso

Paragraph ?. Sv/imming Characteristics

(a) Sh£. k^asscciated skipjackj whale-associated skipjack==> These are skip-
jack £-hoois which follow the lead of kambeisame /"isasking sharks?_7
and ?:rdine whales„ The sharks and whales are wily enough to steal the
sarcmes which the skipjack round up for food;, but the skipjack can thus
take refuge far out at sea from the striped marlin which attack their
schoolSj so it is a kind of cooperative living in which the skipjack and
the sharks and whales mutually help each cthero This phenomenon is often
seen in the North?-a-tern and Zcran areaSo

(b) Drif twood-associatea ■■-' S\^z\ "•..•: hoo'^s are most often seen in the Zunan
Kinan, and Satsunan ar :.oo These are schools which swim along with a
drifting logo (Logs which float vertically are more favored than those

26

J

which float horiaor.tally., and the older and more covered with barnacles,
amphipcdSj and so forth that +>"•- are, the better o )

(c) "Calm ones / tairamono /" ■=■= Schools engaged in this type of behavior
are often seen in the Northeastern areao The fish surround some schizopods
(like the mysids) and lie on the surface gently moving their tails and
eating their prey. The surface of the water where such a school is feeding
is quite smooth vrith only small ripples disturbing it„

(d) "Bait^bed / sodoko /" — This is the term applied when a school
surrounds a school of small sardines., drives them irito a compact mass,
and greedily eats them,,

(e) "Sleepers / toromi / " ■== Tnis term is applied to schools which
leisurely swim around a concentrated school of bait in a state of
exhilaration as if they were dranko

(f) "Jumpers / haae 7" •>= Schools in which the fish chase the bait around
independently J showing themselves at the surface of the water and keeping
no reg'^lar formationc

(g) "Silver flow / ginnagashi /" =- Schools whiehj perhaps because they
have eatsn their fill cr perhaps because they are in a playful moodj, swim
slowly turning frequently en their sides and flashing silver^ Such
schools will hardly ever take chum=baito This is a condition often seen
between Nojima and Kinkazan,

(h) Resting skipjack <=-> Schools are in this condition around Augusto
They swim about and refuse to take chum-=baito

(i) Ascending skipjack =- These are the northbound schools„ They swim
comparatively near the surf ace o

(j) Desr.^ndi^ .^ skipjack =•= Schools returning southward in September and
October, Ti'^y swim deep and fast,

(k) Rov:.:ig skipjack (^eepsea fish) -■= These are schools which swim out
in ths open sea.. The fish in the Northeastern area are almost all of this
typeo They are mainly medium=sized fish, and they are fat. They move
following water temperattires of 20 - 24.°C„

(iy Sedentary skipjack (shoal fish) ■== Schools which stick close to
banks (reefs) and islands. They are mostly submerged in the lower
levels and hardly show themselves except at certain tides or in the
morning and evenings Shcal fish in the South Seas area are either over 1
kan / 8o27 lbs„_7 in weight or under 500 momme /"/4ol4. lba„__7o They occur
in water temperatures as high as 26 ~ 30*^' C„ Suitable depths on the fish
banks are about 150 meterSo The fish are comnaratively iean„

(m) ^Tsukkakari fish" — Same a? dekiuc /'adventitious f ish_7o Fish i^ich
are submerged heir, v che s-orf acs and which come up a few at a time to take
the chumming balto A rather dense school will occasionally come up.

27

(n) Namura =- A general term far surfaced fisho Skipjack schools i^ich
swim about in the open ssa ere called skipjack namurao

(0) Bo-ttom namura -= A term applied tO' skipjack schools which swim sub=
merged belojr the surface.

These are the characteristics which skipjack fishermen in all
localities have since ancient times considered impnTtant not only for the
finding of schools but also for :at3hing the fish,. There are \?arious
local dialect names applied to the same single phenomenonc These terms
have been used from ancient times to the present day without ever having
been standardized o

Paragraph 3 Other Characteristics

(1) Bait=taking characteristics

Skipjack are by natuie averse to eating dead foodo This means that
they cannot be taken anletits live bait is usedo However,, old fish which
have lost- their raigaatcry powers and which drift about in the sea together
with the albaccre wherever the currents may earry them occasionally do
take dead bait a

(2) Predators of the skipjack

They are pursued by thi striped marlin and the okigawara / Cybium
chinense _/o

(3) Vertical movements of the skipjack

It is naturally characteristic of the skipjack to swim in the
s'urface layer of th& O'l-.-raa,, but^ perhaps to avoid the attacks of predators
or perhaps in order to search for food,, they prefer to swim below the
surface ex^^ept whsii. they are feedingo Tliey also come up to the surface
i&ien plafxktin t^; ^■^•esent there;, in the dim light of dawn and evening, and
when the tide creates rising currents^ Hies, the movement of the tide
seasesc, the skipjack which are at the surface tend to submerge. This
tendency is especially characteristic of the schools of sedentary skip^
jacko

The time of surfacing for "roving** skipjack toe is from dawn to about
8^00 a^.u and from about 2300 p^m. to sunsetc They do not surface very
mrucn c -ring the middle of the day when the sun's rays are strong,, Schools
whi:h on rare occasions do come up at such times are "playing" fish and
will not take the bait, iround August when the sun's rays are strong and
the water temperatures rise the surfacing and feeding activities of the
fish become dull and this is said to be the dog-days vacation of the
skipjack =

Within the range of h^bittbls isi?,ter temperetui'es of the sea areas
in which thsy dwelip fr - :,ii.ipj a'Sk uend to prefer areas of c^omparatively
high temperatures in tnfo spring and low temperatures in the fallo There
are also lo;al peculiarities caused by special characteristics of the

28

fishing grounds^ ciirrents, and so forth which are linited to the schools
inhabiting these localities„

@ In what sort of waters are skipjack found?

@ Why do the skipjack migrate?

@ Where is the original home of the skipjack? TJhv do they return there?

@ What do the skipjack eat?

@ TOiat routes are followed by the skipjack which come to Japan?

@ How do the skipjack fishermen divide up the fishing grounds for
convenience' sake'! ^^at na'nes are given to the divisions?

@ Fish are said to be near-sighted, but is this also true of the skip-
jack?

Chapter III

The Skipjack Fishery

In putting a skipjack fishery into operation the first essential
is to understand clearly the habixis of and other facts about the fisho
What it has been possible to learn about the skipjack's habits is actively
made use of in the fishery, and methods are devised to take advantage
of the weak points cf the fish^ The thing to do is to direct the main
force of one's attack tov/ard the weak point cf one's opponent and at one
stroke attain success in fishings In Chapter I we traced the changes
in fishififa -uthods from ancient times to the present dayj, provided materials
for critici.'.ing them, and discussed features which should be corrected.
In Chapter II we considered the natm^e of the skipjack and discussed the
rationality of the old methods of operation in the skipjack fishery in
order to give some indications cf the course to be followed in the futi^re„

The author, vihc has presented the foregoing material as data to be
us.-d in understanding the character of the fishery in its present advanced
5="ate, feels that there is still a necessity for criticism and discussion
of som.e of the basic premises. To be specific, these are the charac-
teristics of the skipjack fishery^

(1) The skipjack fishery has been spread all over the country, and in
each locality it has its cwn peculiar historyo As a result, studies of
all sorts were made in each region separately, conclusions were drawn,
and the people in these arear. believe in those conclusions and identify
themselves with the-.i„ The fishing grounds have been epochally extended,
but people will not lend an ear to conclusions based on the combined

29

scientific data gathered from these broad sea areas, nor will they have
the broad=miadedness to agree with these conclusions^ they thoughtlessly
stick to their old customs and still carry on their conservative opera-
tions. To put it bluntly, the conclusions of the past were derived from
operations in an extremely limited area and they are already inapplicable
to operations in the broad areas of today's fisherjo

(2) The skipjack fishery depends on the skill of individuals^ At the
present level of dissemination of practical fisheries knowledge it is
difficult to expand a fishery which depends on individual skill, and the
development of such a fishery follows an irregular coursso It is diffi-
cult to bring about an overall improvement in catches, and the situation
gives rise to marked inequalities in fishing success,

(3) Under present conditions in Japan the area of operation is restricted
and limited to the waters within the Mac Arthur Line„ It is difficult to
get data with which to assess the situation, and one cannot hope to de=
termine in advance the appropriate policies to be followed in any parti-
cular year's fishingo For the most part each fishing boat has to rely on
its own good or bad luck„

(4) This fishery, in comparison with others, can get by with very little
materials^ Consequently it is an enterprise most suited to the present
conditions of supply in Japan, and is the easiest field of enterprise to
enter, with the result that the concentration of new entrepreneurs in it
has brought about somewhat disorganized conditionSo

Section 1 Fishing Gear

As explained above, the skipjack fishery has followed its own
particular course of development in each area and has relied on the skill
of individualSo As a result there are many local peciiliarities, but the
essentials of both gear and methods do not differ greatly „

Paragraph 1 Pole and line gear

1, Poles

The material is chiefly long- jointed bamboo produced in the locality
vriiere it is used, Gosan bamboo^ hatake bamboo, and karatake bamboo are
widely employed. Requirements for skipjack pole are (a) that the bamboo be
straight and that there be no danger of its breaking, (b) that it be stiff j
and (0) that the elasticity of the tip be great.

The dimensions of the pole should be such that it will be thick
enough for the user to grasp it firmly with one hand and not too heavy
for him to manipulate easily. Strictly speaking, the size of the pole is
determined by the strength and sk^ll of the fisherman, and generally
skipjack fishing poles are selected and prepared by the fisherman himself.
The usual standard for poles is 18 = 20 feet long with a diameter of l,iU
to 1,8 inches at the br/rc and 0,6 to 0o96 inches at the tip. In some
localities the dimensions of poles used for bait fishing are different

30

from those used with artificial liires. The latter are somewhat slenderer
and about 15 = 16 feet long so that they can be managed more dextrously„

The butt of the pole is wrapped with string to provide a firm gripo
This twine is of hemp, iwaito t'^-Jt or cotton of about size No,, 20, and
it is wrapped around the pole at from five to seven places to the width
of about 0o6 inch and with about the same space between wrappings. This
part of the pole is called the grip / nigiri or tedokp_7« ^ile the pole
is not in use the hook is stuck into these wrappings to prevent the line
from tangling^ A thick wrapping of strong hemp twine is put on the tip
to form a snake's mouth (pot) / loop_7 to which the fishing line is
fastened. The method of making this knot varies wi'oh the locality, but
the essential thing is that it be tied tightly so that it will not slip
and that it will not make the manipulation of the pole unnaturalo

2, Fishing line

As a rule the line is 1 to 1-|- feet shorter than the pole„ It is
divided into a main line and a leader » The former is sometimes called
takayama and the latter koyama„ (Yama is a dialect form of yona meaning
strings) Different materials have been used in different localities and
at different periods. The following are two or three examples of the
present practice,

(1) An example from the Northeastern area (see Fig, 6),

The main line is 11 feet of iwaito ,08/, to ,096 inch in diameter.
The leader is 1 foot of three=strand righthand twist wire, one end of which
is fastened to the hook while the other end has an ej'-e for attaching it
to the line. The main line and the leader are joined by a piece of No, 12
cotton line one foot in length which is doubled and twisted to the left
with an eye in one end and a knot on the other,

(2) An example from the Kagoshima area

The msin lias is made of high-grade hemp, ,56 inch in circumference,
three strands being twisted together, or it is made of high-grade hemp
served .1th No, 50 ■= 100 cotton line, the finisned line being about ,36
to .V- inch /in diameter?_7» The leader is from 9o6 to 10,2 inches long
and one end is fastened to the hook. The material is No, 28 or 29 vdre
(about the same size as No, 22 cotton line), three strands with a right-
hand twist, and both ends are served,

.3) An example from the Shizuoka area

The main line is kanabiki /~?_7 hemp, hand-twisted with two strands,
diameter ,36 to ,4.8 inch, length 12 to 16 feet, undyed. The leader is the
same material and the same size as the main line but is dyed indigo,

(4.) An example from th- Chiba area

The main line is home-made from high-=grade Noshu hemp. It is about
18 feet long, two strands with a left twist, and is undyed, Tne leader is

31

^ genuine gut artificial gut (Akita line)

C^ ^. — --^ - -

f- indigo-dyed hemp ^^^ undyed hemp

hemp (2o4") _^^

^ ^^~ wire _^,.,..g-jrf^'^^hemp

wire ^*^ hemp ^an emmple from Kagoshima)

K o-.v.ici'vKJcmc

wire cotton ^' iwaito (an example from the

Northeast)

grip pole loop

Figure 6 Poles and lines

Oo90

90,99

Pi- ..e 7 Skipjack hooks (actual size)
1 <= 4 Tosa Tankichi type, 5-12 ordinary skipjack hooks

made of high-grade Hikita hemp dyed indigOj with two strands loosely twisted
to the lefto It is about 13 inches longo Instead of hemp for the main
line some fishermen use artificial gut of 8 to 9 momme weight £ 1<,06 to
lol9 ounces per five=foot fathom_7si with NOo 28 or 29 cotton for the
leader o

(5) An example from the Kochi area

The main line is high-grade Noshu hempp two =■ strand, righthand twisty
diameter o06 to o096 inchp length 12 to 16 feet, undyedo The leader is
made of the same kind of hemp either dyed with indigo or made of a mixture
of undyed and indigo-dyed hemp fiberSo It is two^strand, righthand twist,
and from 1 to 1„2 feet in length„ The thickness depends on the size cf
hooks to be used, ranging from oOlS to about o096 inch. In seme excep=
tional cases -ohe leader is ser-ved.

The above data on the materials used for skipjack fishing lead to
the following conclusionSo

(1) Not much attention is paidj as in other types of angling, to the
fineness of the line, strength to withstand the skipjack's vigorous
strikes being more sought after^ and therefore material which is unlikely
to break is Ghosen„ In order not to alarm the fish, the leader, the part
of the line which is in the water, is dyed with indigo to the same color
as the waters of the KuroshiOo This practice has been carried on since
rather ancient times and has spread all over the country, for which reason
it is thought that it must be fairly effectiveo There is a need for further
investigation on this pointo

(2) The fishing line is replaced constantly during the fishing season so
that it will have its maximum tensile strength at all timeSo The work of
hooking fish is very Tiolent so a great strain is placed on the line and
excessive force is applied to ito When the school is large, the operation
continues for a f&lrly long time during which the fishermen must bring in
as many fish &.2 >,o^ssible„ To make sure that the line does not break during
this time they shange the leader frequently^ keeping a supply of spare
ones handy„ The main line will last for about ten days of fishingo The
leader ne- -'.s to be strong enough to stand up under a whole day of use,

no matter how many fish may be caught during the day,, "HTie best material
is one which, even though it may weaken considerably when soaked with water
for a long time, can be unconditionally guaranteed for a short period of
timeo On this score hemp is the most suitableo The use of wire for leaders
is n x a question of strength or weakness, but rather of what will catch
the ffiost fisho Aside from the effect on the catch there is no pressing
reason for using it„ In fact wire which is not completely rustproof
probably has an adverse effect on the catch. In the last analysis this
is a point which should be investigated on the basis of the catch ratios„

(3) The question cf vihat kind of fishing line is best has hitherto been
taken up only from the po''-r.'" of ^iew,, not cf the effect on the catch, but
of how a hooked skipja"^- could be got into the boat without being dropped,
in other words, caly the strength of the line was considered, and the

33

fishermen have tended to ignore the question cf what effsct the thickness

and color of the line may ha*s on the schoclSo In other wordSj, the type

of fishing line ussd in the past indicates that it has been easy to
catch skipjack o

(4.) Lately the fishermen have come to the point of considering the effect
of the line en the school as well as its strengths In order to keep the
strength of the wire and hemp which have been used in the past and at the
same time to reduce the thickness of the line and to get a clear material
which will do away with disadvantageous color and sheer, in the water,
they are using ir.ostly artificial gut for the maiE. line and high-grade
genuine gut for the lead8r„ Nylon line and other new materials-, are also
getting some attentiono Impetus has been given to this movement by the
postwar expansion cf the skipjack fishery and the entry into it of new-
comers who do not have the skill and experience and who have not been
accustomed to making their own gear^ As a result a wide variety of
materials other than those used in the past are being popularized, however,
because of the high price of some of these materials and the difficulty
of obtaining them at present they have not j&t come into universal useo

3i, Hooks

Two types of hooks have been used since ancient times for skipjack
fishings They are bait hooks and squid hooks / artificial Ixires _7„
The skipjack hook is charaeteriized by its lack of a barb, and where a barb
is present it is merely a vestigial small bend in the tip of the hooko
This peculiarity is related to the habits of the skipjack, is revelatory
of the peculiar character cf the fishing operatioHj and is a reason why
the skill of the individual fisherman is emphasissedo There is some
variation depending on local tasteSo

(1) Bait hooks

These hocks are either of the round type or a compromise between
the round typ.- and the angular type, They have no barb (although some have
a vestigial :..ne), and the space from point to shani-: ie broado Sizes from
o96 inch to 2o76 inches are used. Materials are either steel or tempered
iron and in both cases the hocks may be either tin-plated to give a bright
finish or they may be burnt blacko The size of the leader is varied to
suit the size of the hook.

The size cf the hook which is used depends on the size of the skip=
jack being fished (depending on the season) or on the size of the baito
Ca) medium skipjack (under 1 kan /°8„27 lb3„_7) =- The hooks used are
chiefly lo32,, 1.44, or lo74. inches in size.

(b) large skipjack (over 8o27 IbSo weight) =■= The hooks used are 1,8<,
2„04<. 2o28, or 2„ 52 inches in size.

When anchovies lo2 to io8 inches in length are used as bait, the hooks
used are less than lo74. inches in sizSo When the bait is herring, anchovy,
or sardine from 1„8 t.-. 3o- z.acii%& in length, the hooks are of sizes smaller
than 2„4. incheSo \f^xh sardines or mackerel^scad 3o6 to U^2 inches in
length hooks of about the 2„4 -inch size are usedo The design is different

34

Figure 14 Methods of

baiting hooks

body

lead

tail

Figure 8 Horn lure

trunk

k

tail

tinned

fishskinj
feathers

Figure 10 Feather lure

35

in each locality. Until the war the nationally famous Tankichi hooks,
which, aa shown in Figure 7, have traces of a barb, were manufactured.

(2) Artificial lures

These have been widely used since ancient times, with excellent
results, and there are many varieties of them.

(a) Horn lures

These are composed of the "mag" /"body of the lure_7 and the "eba"
/"tail of the lure_7 (these are the terms used in the Kagoshima area) .
The body of the lure is made of cow horn, water-buffalo horn, deer horn,
goat horn, whale bone, spearfish spears, ivory, and so forth, and a
round-type barbless hook is inserted in it. Then to make the vrtiole thing
look like a squid the belly skin of a tetraodont or some feathers are
tied on. This tail is made long enough to fully cover the point of the
hook. TUth the whole lure from 3.36 to 3.6 inches longo the body of the
lure will be about 1.^4 inches long and about 0.6 inch in diameter, and
the tail will be from 1,8 to 2,16 inches long. It is thought to be
effective to inlay the body of the lore with various types of shell.
Abalone, ?rtiite pearl shell, black ner.rl shell, tataki shell, roppo shell,
shabo shell, tarashi shell, and Chrysocroa elegans are used for this
purpose. The effectiveness of horn lures varies depending on the type and
coloring. In general it appears that either red or black is best. It
is said that red ones are good in clear water irtiile black ones are good in
either clear or turbid water.

The poles used with horn lures are male bamboos with a strong mid-
section and a flexible tip, the tip beings .2A inch in diameter, and the
line is about 4 feet long, • •.•

(b) Feather lurea (bake, buppai, or sawakaeura)

Thet J lis; iS have tin fitted to the base of the hook and the point
covered by mite feathers and irtiite or black fish-skino The overall
length is about 1,8 inches. The tin is about ,2U inch in diameter and
the hook is cast into It, Feathers and quills are tied to it; soraetiraee
brass ^ubing is used around the tin, and the lures are made in many
different shapes.

With these lures poles v^ich have a strong mid-section and a flexible
tip are used. The same line is used as when fishing with bait. These
■.urea are chiefly employed when the skipjack are biting well. They are
held in the water so that the upper end of the lure is one or two inches
under the surface and then the tip of the pole is agitated, HVhen a skip-
jack is hooked, it is scooped up in a dipnet^

(c) Jigs Ashaburi 7 (trolled feather lures)

This type of Ix'.r.. l5 made tic resemble a squid. It consists of a
flat piece of leuu about 3 inches long and .^8 inch wide or a cylindrical
lead about 1.2 inches long by .3 inch in diameter to which six or seven

36

feathers or long narrow strips of ballconfish skin are fastened. Most
of these hooks have barb5„ On the fishing grounds they are trolled from
the stern of the boat on 20 to 50 fathoms of liae„ If they take a skip-
jack on this gear, the fishermen Judge that there is a school in the
vicirdty and begin fishing. They are employed particularly after the
latter part of September when the schools go deep and become permanently
located on the shoals „ There are also many types of these lures„

Paragraph 2 Bait

As set for-oh in the section on the na&its ci tne skipjack, the
conditions which govern the use of bait for skipjack are that it be live-
bait and that it suit the skipjack's taste. Furthermore,, fishes which
meet these requirements mfust also be easily taken in waters close to
Japan and they raiast be available in large quantities in a live state^,
At present the various kinds of iwashi are used for the most parte

1, Baits used in skipjack fishing

(a) Erigraulis iai2£!lfei^ Z"^_7 -' '^-- >^p--^ -■ i^ pivferrai by the
skipjack beats in the Kagoshima., Si-iizuoka^ Chibaj, Ibaragi^ and F'akushima
regions c

(^) Decaoterus giroaii, =- Usea la the Tckushima and Chiba areas,,

(c) Sardinia melanc sticta =>•= Used almost all over the country^ it
occupies the first place for quantity,, but the main areas of use are
Kagoshima J Koshi, Chiba. Miyazaki, Iwate;. and Kianamoto,

(d) small mackerel- scad = = Kagoshimay Miyazakij Tokushimay and Mie
areaSo _

(e) small mackerel ■== Kagoshima, Miyazakij, Tokushima,, Kochij, and
Iwate area So

(f) i^'^ashi -- Kagoshima, MiyaaaKi, Tokushimdj Ifekayama, Miej, Kanagawa,
and Aomori B~'i?>-.,

(g) sr Miyazaki area

(r.^ ..io_j,_iiiacK.ergi=scad ■=" Miyasaki area
{i. '-^J L katakuchi iwashi^' == Kschl area

'1-u addition tc these specieSj, mysids and living larval fish and eels
are •-.sed for chum bait,,

2,, liow bait iwasni are kept a-ii's

Live bait is the animal In its natural living state, and in many
jases it is the best type of bait. When baits other than live bait are
usedj it is extremely difficult to catch fishj since ancient times live
bait has been used almost exclusively and it has been easy to take fish
with ito Because the bait fish are in their natural living state it is
necessary to ise the greatest care in keeping and transporting therhs, and
even then they occasionally will die.

As the ski^^'; . season approaches, bait-pounds are set up at the
baiting grounds, commonly called ssabaj, which are usually places inside

.37

bays where the waves do not come directly in from the oceano These
pounds are made of palm fiber netting with a fine mesh„ The meshes are
very small so that i7?ashi 1„2 to 2oU inches long will not get stuck in
themj and the water circulates well through the net providing a thorough
natural changing of the water which is a requisite for holding bait. The
size of the pounds varies, there being no particular standard, but they
are commonly about 9 feet by 9 feet by 6 -- 12 feet„ They are made with
wooden frames over which the web is stretched like a bago These pounds
are set out in the water in large numbers for the purpose of keeping
baito

(1) The capture of iwas_hi for bait

Various types of gear are used, each locality having its own pecu-
liar gear„ There are some types of gear which are specialized for use
in taking iwashi for bait, and in other cases gear designed for other

fisheries is used as convenient„

One of the kinds of specialized gear is a small-scale set net
(commonly called a crystal net £ s-aishoami_/ or machine net £ kiVaiaiT:i_y')
which is set in bays across the paths of migration of the iwashi as the
skipjack season approacheSo Iwashi which enter the heart of the trap
are carefully taken out with dipnets in such a way as not to injure
or weaken them and are placed in bait scows or live=poundSo They are
then kept in the live-pounds in quiet waters as described above „ Iwashi
which enter large trap nett; and other types of fishing gear are also kept
for bait in the same manner „ In addition i\yashi taken in purse seines,
lift nets, and stick-held dip nets are also held for baito

(2) How the fish are kept in the live-pounds

It is essential from the start to accustom skipjack bait to swimming
in a confined spacso In other words, it is necessary to take fish which
have been swimming about in a broad expanse of water and, for convenience
in handling, conr.-i-utrate them densely in a cramped space,, If the space
in which the fisxi can swim is suddenly cut down, many of thera will die
so it is important to set up live^pounds of various sizes and gradually
accustom ths bait to smaller and smaller oneSo Iwashi at the time of
capture are referred to as '♦wild bait Z"araesa7" or "wild iwashi /"arajwashi?".
After the^' have become accustomed to captivity they are called "tame
iwashi ^ iketsuke iT>ashi 7" . For keeping a dense school of fish in a
small space the live-pound should be set up where there is quite a bit
of current, and in order not to lower the vitality of the bait a quiet
spot sheltered from the waves and not subject to fluctuations of tempera-
ture and water composition should be selectedo It is also necessary to
provide suitable shade and to guard against attacks by predatory birds
and fisho When the bait is to be held for a long tirne^, suitable food must
be provided to deep up their vitality, and dead fish must be removed in
order to avoid the bad effects of decompositiono

(3) Supplying the bait t:, the fishing boats

38

The "tame iwashi" are us^ially supplied to the fishing boats after they
have been kept in the live-pounds for a week or longer and are thoroughly
accustomed to living in a confined space „ They are handled with carej and
the operation is carried out in the_form of a commercial transactions, for
example, when a bucket holding 8 sho / 3ol8 gallons_J' is dipped from the
live-pound, a bargain is made for so many yen per bucket, Latelyj because
of the general shortage of bait;, the skipjack fishermen have been making
every effort to assure themselves a supply, and there are some who make
contracts beforehand with the bait suppliers while others have hired persons
who do nothing else but buy bait for them„ At times they may even be forced
to load "wild bait" in the boats„

(4,) Bait in the fishing boat's bait wells

Skipjack boats are equipped with live bait wells in which are kept the
iwashi from the live-pounds. The capacity of the live wells depends on the
rate at which the water in the boat can be exchanged and also on the species,
size, and condition of the bait and the degree to which they have become
accustomed to cramped quarters.

(a) Deaths of bait fish due to insufficient oxygen in the water are
more frequent with larger fish than with small oneSo

(b) Deaths resulting from injury in handling and from stimulation and
excitement by conditions in the bait wells are more frequent with small fish
than with large ones.

(c) As between the ma iwashi / Sardinia melanosticta / and the katakuchi
iwashi / Engrauli s .jaTPonicus /„ the former is more resistant to injury and
excitement, while the latter is comparatively resistant to oxygen deficiency,

(d) The water temperature has an effect on the viability of the fish.
If the temperat'ore rises, injured or weakened fish will die all the faster.
If the temperature falls, even fish which are in a dying condition will
have their lives prolonged somewhat, Consequentlys the number of deaths
in the bait wells increases and decreases as the water temperature rises
and falls,

(e) Resistance to death from lack of oxygen is gi'eater in the anchcry
than in the sardine, and greater in small sardines than in large ones. When
the fish in the live=well mill around excitedly^ it is because the oxygen
co!icentration is insufficient, being below 1 cc per liter, and the water
rust be changed. It is said that the maximum concentration of fish in a
iive-well which is advisable is about 8 gallons of sardines per cubic
meter,

(f) There appears to be a tendency for more bait to die of injury,
excitement, and so forth when the fish are noticeably lean than when they
are fat.

In selecting ba:^t fish the first consideration is to choose those which
the skipjack like to eat, and the second thing to consider is the ease with

39

which they can be kept aliveo From both points of vie-^ we mr-; conclude
that the best skipjack bait fish are fat sardine frotn 2^U to 3.6 inches in
length.

Paragraph 3 Skipjack Fishing Boats

It is not too much to say that the factor which decides the success or
failure of skipjack fishing is the efficiency of the fishing boat. The
capabilities of the boat effect the length of the fishing season, the range
of the fishing groundSj. the number of days of operation, the number of
fishermen employed, and the ability to hold the catchc In short, the type
of boat used affects the #iole operation.

As set forth in the first part of this paper, the history of the devel=
opment of the skipjack fishery has followed the same path as the history
of the development of skipjack boats. In the period when Japanese- style
boats powered only by oars were in use, the fishing grounds, season, and
catch corresponded to the potentialities of these vessels. The years in
which ^stern=style Yaketama / hot-bulb_7 boats were used saw a corres-
ponding development of the fisharyj and at present when steel-hullad
Diesel-powered boats of over 100 tons displacement are usedj the fishery
has reached a stage at which fishing car. be carried on at any time through-
out the year and in far distant waters, and fishing techniques can be fully
exploited.

Fishing boats can be generally differentiated as wooden vessels or
steel vessels. There are aj.most no boats which engage solely in skipjack
fishing, the boats generally being called skipjaek=tuna boats. They carry
on both skipjack and tuna / longline_7 fishing and are equipped for both
types of operation. The design and layout of such a vessel is shown in
Figure 13 <>

Tne practical requirements of a skipjack boat are

(a) A strong hull, seaworthiness, and ease of operation,

(b) Ability to stay at sea for at least two weeks, and a speed of at
least 8 knots,

(c) ^ell-appointed bait tanks with a large bait=holding capacity,

(d) Good ice storage and capacity to hold a large quantity of fresh
fish,.

(e) Room for a large number of workers,

(f) Good communications equipment,

ihese points will be further discussed below„

1, Hull

Present"day skipjack boats are either of wood or steel construction.
Wooden boats are from 60 to 135 tons; the majority of them are below 100
tonSj and the bulk of them ere in the 80 to 90 ton class. Steel vessels
are from 100 to 300 tor-, u.-, mdjcrity being between 120 and' 180 tons. The
tendency is for largei and larger boats to be used. The reasons for this

40

are (a) safety at sea, (b) greater cruising range, (c) capacity to hold
the necessary quantity of bait, (d) bigger fish holds, (e) increase in
the number of fishermen employed, and (f) increased efficiency of opera-
tiono In addition to this tendency toward larger vessels, there are signs
of a standardization of design in all parts of the country, and steel
vessels are replacing wooden oneSo The increase in size is naturally
limited by the peculiar nature of the skipjack fishery, and with the present
character of the operations and the facilities available at fishing ports
steel vessels of about 150 tons are the most practical type,

2, Cruising range and speed

Since the recent tendency is for skipjack boats to engage also in
longline fishing, the boats operate the year round, fishing grounds are
gradually being extended farther out to sea<, and operations have become
more aggressive „ As a result a need has arisen for the greatest possible
cruising range, and along vath this attentica crast be given to speed,
horsepower, and type of engine,

(1) Types of engines

The two types under consideration are the Yaketama engine and the
Diesel engine. An investigation of vessels already in operation sho^s
that from the point of view of fuel oil consumption a 1^,0 HP Yaketama
engine uses Oo^ ton per day while a Diesel engine of 160 HP uses 0.7 ton.
Thus for its horsepower the Diessl uses less fuel than the Yaketama.
Lubricating oil consumption varies with the make of engine, but the
Diesel surpasses the Yaketama on this score by about one-fourth„ This
difference in oil consumption is an important point for skipjack boats,
which are coming to be used the year round. The Diesel engine is far
superior as far- as fuel consumption is concerned.

The Yaketama engine is somewhat superior to the Diesel in power
output in relation to horsepower, but not enough so to offset the greater
fuel consumption. Diesel engines are most suitable for skipjack boats
and most of them are in fact adopting such engines. Howeverj Diesel
engines are used chiefly where more than 100 HP are required. Tne airless
injection type of around 200 HP, using 180 grams of fuel per horsepower
pel hour and 2 grams of lubricating oil^ is very dependable and durable,
end is the most suitable and most economical type of engine for these
joats, which fish in distant waters and as a rule operate for long periods
of time alone.

(2) Horsepower and speed

In recent tim.es the need for speed has been discussed from various
points of vieW;, but i'" th~ case of skipjack boats speed is necessary in
order to (a) shorts;, the dead time spent in going to and from the fishing
grounds, (b) increase the number of cniises which can be made during the
fishing season, and (c) to give the boat an advantage over other boats
operating on the fishing grounds„ The speed is related to the design of
the hull and the quality and power of the engine. Skipjack boats which

/I

have adopted Diesel engines are powered so that those under 50 tons have
about 2.5 HP per ton, those of around 100 tons have 2 HP per ton, and those
in the 180 ton class have about 1.3 HP per ton. The object is to maintain
speeds of around 10 knots.

3, The problem of bait tanks

Bait tanks are the most characteristic feature of skipjack boats.
Their capacity is related to the number of operations which the boat can
carrj out on the fishing grounds, and by extension to the amount of the
catch. It sometimes happens that boats encounter large schools of skip-
jack which they have gone to much trouble to find, and then are unable to
operate because they arc out of bait. Indeed, bait is life and death to
the skipjack fishery.

(1) The bait tanVs are supposed to hold the bait fish in a healthy condi-
tion without lowering their vitality or causing ther to die until the time
'ihen they are to be used on the fishin{_: grounds. In order to accomplish
this the following requirements must be met.

(a) The bait fish must be kept as quiet as possible to prevent any needless
waste of their energy. For this reason the tanks are located amidships

on the center line of the boat where motion is at a minimum and where
they are convenient for use. (See Figure 13)

(b) In order to maintain the vitality of the bait fish there must be a
thorough circulation of water. This factor has a bearing on the amount
of bait which can be kept Vidthin a given space. Water exchange is either
natural or powered, and in some cases both systems are used. In the
natural water exchange s;;-3tem openings are provided in the hull '^/ithin
the bait tanks so that the water will circulate naturally. With a powered
system a water pump is installed in the engine-room to provide a constant
circulation of water. Ordinarily the pump keeps the tank constantly filled
and makes th.e water circulate within the tank; the overflow runs off

from the hatch-coaming on deck through a pipe which leads to t^e side of
the boat. This nethod provides approximately 30% more water than the
natural system and as a resiilt the amount of bait which can be heir' is
greatly increased. A completely water-tight electric light provides
illumination within the bait tank. This greatly increases the viability
of the bait and lowers the death rate.

(2) I/icreasing the holding capacity of the bait tanks

By increasing the capacity of the bait tanks it is possible to lengthen
the operating time on the fishing grounds and increase the catch. This
increased capacity can be attained by installing more tanks, building larger
tanks, and by using a powered system to exchange the water in the tanks.
However, the balance of the vessel as a whole must be considered in adopt-
ing these measures,

4., Sto'-'age of the catch and ice capacity

A2

The ideal fishing boat is one vrfiich car. bring to market the greatest
possible quantity of fish in the best condition of freshnesSo If we look
at the actual capacity of boats of various sizes.

Size of Vessel Fish Stowage Capacity

30

=

50 tons

50

=

70 tons

70

■=

100 tons

100

=

150 tons

150

=

180 tons

3s 500 - 7s000 k^ /l28,945 =■ 57,890 lbs. 7
7p000 = 8j500 kan i 57,890 - 70,295 lbs„_7_

;pv.^w - 8„ 500 kan ^ 47,890 ._, ..

8,500 = 11,000 kaS 4_70,295 - 90,970 lbs„_7,
11,000 " 16,000 kan / 90s970 - 132,320 lbs,
16,000 = 20,000 Ign £132,320 <= 165,400 lbs

i

The above figures represent the standard quantities which can be
stowed v/hen the catch is properly refrigerated with ie-e to keep it; fresh.
The amount of ice used varies mth the season and the length of the trip,
but in general it is 25/6 to 35j6 of the weight of the fish to be refri-
gerated. When fish are kept iced for use as fresh fish, each 100 kan
C^21 lbs„_7 of fresh fish requires about 40 cubic feet of spaceo The
amount of ice carried by fishing boats is as follows §

Size of Vessel Average Weight of Ice

70 - 100 tons 32 tons

100 =• 150 tons 53o7 tens

over 150 tons 54- tons

These figures will vary depending on the efficiency of the insulation
in the fish holds. Larger vessels are installing refrigerating machinery »
Temperatures in the fish holds should be from 25 to 35 Fo

5, Personnel carrying capacity

Since skipjack fishing is based on individual skill, it is necessary
to carry as mar.-./ fishermen of the highest degree of skill as possibleo
This will nat irally be governed by the living space and acoommodaticn s
in the boat and by the available working facilities^ By working facili-
ties are nieant the bowsprit and fishing platforms, for the construction
of which there are various designSo

Tne bowsprit is of steel girder type, combined '.vith galvanized gas-
pipe. It is broader at its outboard end and the inboard end is attached to thp
fishing platforms. It is designed to permit more men to engage in the fishing
t^.an was possible in the past, and is so constructed that the fish taken will
ciide along it into the boat.

The fishing platforms are installed along both sides of the boat from
bow to stern, and forward of the gangway in the middle of the boat the
bulwarks are extended to their outer edges, and the footboards on their
upper surfaces are covered with water-tight planking 5 aft of the gangway
the footboards are mado of galvanized gas=pipe„ IhB whole construction
is strong enough to .vxTihstaad the pounding of the waves.

43

The capacity of the fishing platforms and bowsprit installed on a
skipjack boat determines the number of fishermen,

6, Water spray installations

This is a special type of installation which utilizes the habits of
the skipjack to the advantage of the fisheryo A galvanized iron spray
pipe about 75 millimeters in diameter is attached from the end of the
bowsprit along the edges of the fishing platforms to the stern. A
suitable number of spray nozzles are provided and a pump in the engine-
room supplies water for the spray » The power of the pump is determined
by the amount of water required and the distance to which it is desired to
spray it,

7., Communi'ations equipment

rnis is essential for the safety of the vessel as well as to keep a
firm grasp on the fishing situation and to operate the boat economically.

According to figures published in October 19a7 by the Survey Depart-
ment of the Fisheries Bureau,, Ministry of Agriculture and Forestry, there
were as of June 194-7 1;,4.20 skipjack and tuna boats registered with a total
displacement of 60,4.79 tons^ giving an average per boat of 4-2 tons.

Table 3 Skipjack and Tuna Boats (70 tons and over) and
Organizations Operation Them (October 194-7)

Organization

Number of Vessels Organization Number of Vessels

Ichimaru Fisheries COc
Inui Steam-ship
Uwashima Trs'
Kawanami '^ .-
Kan to Fii^
Kato Fisheries
Kyokuyo Wh-ling
Kyodo Fi-.:.-rie3
Klyotoshl Fishing
Goyo F" --aeries
Kosei i 1 sher ie s
Sarkel Fisheries
Sank J- Steamship
ShOiNQ Fishing
Shima Fisheries
Joyo Fishing
Takaoka Fisheries
Daito Fishing
Taiyo Fisheries
Taiy5 Fishing
Taiko Steamship
Tagomura Fisheries
TaKrayo Fisheries
Tokai Fisheries

3

25

2

1
2
1

1

Tohcku Promotions

7

T^ku shima Fishing

1

Nakagawa Navigation

7

Nankai Company

2

Nishi Nippon Fisheries

2

Nichibei Fisheries

1

Nichirc Fifhing

u

Ka-na Kat-s-iura Cooperative

2

Riga Shi Nippon Fishing

1

Fuyo Fisheries

2

Fuji Fisheries

5

rtokoku Fisheries

10

Hcko Fisheries

11

Hoyo Fisheries

1

Marako Fisheries

1

Marudal Fisheries

1

Marashin Navigation

1

Miyako Fishing Co„

1

Wiram Nippon Fishing

u

fiiiO'' hi!rroine Fishing

1

Yamato Fishing

1

Wakadori Products

1

'+4

Since the end of the war the skipjack and tuna fisheries, following
the trend of the times, have started to work anewo Table 3 shows the
vessels in operation and the organizations operating them in the autumn
of 194-7o Almost all of these organizations started out fresh after the
war with newly constructed boats which in their characteristics and
size are excellent for skipjack and tuna fishing. However, in view of
the present shortages of materials there are naturally defects of quality.
As this -survey was a general one, there were some emissions, and some
changes have taken place since it was made.

Section 2 Fishing Methods

Paragraph 1 Bases fcr the Fishery

When the fishery is, as it is at present;, composed of various
specialized elements operating together, the choice of a fishing base
and the facilities, size, and ease of supply at tfiat base have a pronounced
effect on the operation of the fishery.

The following points should be considered in selecting the base for
fishing operations,,

(1) Having good fishing grounds within a short distance

This shortens the dead time required for going to and from the fish-
ing groundSj lengthens the operating time on the grounds, increases the
number of fishing trips which can be made during a limited fishing season,
and brings about increased catches.

(2) Ease of obtaining belt

This mec:..iS a place very close to the baiting grounds, where it is
possible to secure at all times the bait which is essential to this
fisheryo ,

(3) Ease of obtaining ice for preserving the catch

The fishing season comes during the season of high temperatures, and
because of the way in which the boats are equipped, ice is absolutely
etssential for holding the catch. Difficulty in obtaining it affects the
operating time of the boats and the number of hours they can fish during
the season,,

iU) Adequate port facilities

In order zo enable the fishermen to rest after they have been at
sea for from two to thre?^ weeks, fighting to get a full load of skipjack
while the boat i? -.ocking violently, it is essential that the port be
fully equipped with breakwaters, cargo handling facilities, fueling, and
watering installations. Such facilities make it possible to shorten the
length of time in port and increase the time spent in f i.ahing„ It is bo
find out wl.at £)Ort of In.ck each boat is having and to

necessary that communicaticns facilities be adequately provided in order to
be able to find out vriiat sort of luck each boat is having and to coordinate
future operationSo

(5) Good land and sea transportation

Skipjack fishing bases are selected on the basis of the above require-
mentSo

The bases being used at present are in general as follows^ The
asterisk denotes bases which are nationally fair.ouSo

(a) Boats operating in the Satsunan area

Kagoshima Prefecture - ♦Ya'magawa, *Makura2aki
Kumamoto Prefecture = Ushibuka
Kliyazaki Prefecture = Aburatsu

(b) Boats operating in the Kinan area

Kochi Prefecture - ^Shimisu, *Susaki, fihiroto
Tokushima Prefecture - several ports
Wakayaraa Prefecture =■ ^Katsuura, Tanabe, Kushimoto
Me Prefecture ■= Owasej, Hikimoto, Hamashima; Nakiri

(c) Boats operating in the Zunan area

Shizuoka Prefecture - ^Yaizuj Shimizu
Kanaga^va Prefecture - ^Misakiy Kurlhama
Chiba Prefecture = Tateyama, Katsuura

(d) Boats operating in the Sanriku area

Ibaragi Prefectvixe =■ NakSj Kuji

EtUfushima Pssef ectare = Onahaifia

Myagi Prefecture --^^Ishimal'-is, ^Onagaway *Kesennuma

IvTate Prefecture - Ofunato^ Miyako

Aomori Prefet - Hachinoe

This is the situation at present, but with the increasing size of the
boats and changes in the conditions of the fishery the bases are always
shifting „

Paragrapr. 2 Fishing Grounds and Fishing Seasons

The subject of fishing grounds and seasons has been pretty well
exharsted in the section dealing with the distribution of the skipjack,
but it should be noted in addition that they are not the same from year to
year because of variations m the movements of the schools and in the
oceanographic condition3„ Despite these considerable variations, however,
a study of skipjack catches of the past, with a consideration of various
other circumstances, can lead to some general conclusionSo

1, Satsunan area

This area has its center from Takeshima to the Tokara ISo and extends
past Amami Oshima and the Ryakyus to the east coast of Taiwan, covering a

A6

distance of 500 miles north and southo The important fishing grounds
within the area lie from off the Satsunan Shichlto south to the waters
northeast of Miyakojimao

The season begins in February around the Amami ISo and the Iheya ISo
Fishing begins around ^he Tokara ISo in March;, and in April catches are
made all over the area. In June and July the season is at its height in
Okinawa and Taiwan waterSo In May and in the fall season from August to
October the Tokara Is, area is regarded as an especially excellent fishing
groundo At the end of the season in November and December the schools
move back and the season ends ^ere it began around the Amami and Iheya Is,

Fishing grounds in the Satsunan area are limited to reef areas, and
the grounds are developed around the reefso Fishing is done within the
100-fathom line and around the many s-anken reefs from the Satsunan Shichito
to the Tokara, Amami,, and Okinawa Islands, Especially notable fish reefs
are Gonsone, Gaja I„, Nishisonej, GajatakOj Gogosone, Hachigosone,, Ogansonej,
Oganmitsu, and Yckoate Nishisonej all of which lie in the western part of
the area enclosed by a line drawn from Gaja I, in the northern part of
the Tokara ISc to Yokoate I, in the south, andj, in the Amami Is„,
Torishimasone, Gyoseisonej Seigyosonej, Nishisonej and otherSj, all of them
around Torishima in the western part of Tokunoshimao There are many
other fish reefs in addition to these. Changes in oceanographic condi^
tions bring about remarkable fluctuations in the catches made on these
reefSj and there is a certain amount of variation from year to year. The
boats move from reef to reef depending on the fishing situation. The
reefs all have depths of 30 to 100 fathoms.

The fishing seasons and fishing grounds in this area are roughly as
follows. In the spring season from February to May fishing is centered on
the Satsunan Shichito and is carried on at the fish reefs of the Tanegashima
and Yakushiria areas. In the summer season from June to August the fishing
grounds de\'elop in the waters east of Taiwan, In the fall reason fishing^
is carried on in the grounds near the laeyama Is, In the past some boats
used to go down to the Borneo and Celebes area during the winter season.

The most profitable fishing in this area is that for sedentary
schools in the spring season and en the Yaeyama Is, grounds in the fall,

2 J Kinan area

The season in this area is generally from March to Augustj 'and the
grounds are comparatively close to the coast. They vary from year to year
as the currents shift, but in the Tosa area they are 20 to 30 miles south
of Tosa, that is, in the waters north of the main stream of the Kuroshio,
Fishing is carried on here by small vessels beginning in the middle of
April,

(a) In the waters 50 =■ 24-0 miles southwest and south" southeast of Ashizuri
Misakij the first fish are usually seen between the middle of February and
March. The season opens when the water temperatore is around 19 - 20° C„

1.1

(b) Around the sunken reefs in the vicinity of Okinoshima big catches are
made fuffiffl April to June in years when the current through the Osumi Strait
strikes in strongly to the coast at Ashizuri Misaki and the water temperature
is about 20°C„

(c) In years when the Kuroshlo comes in weakly toward Muroto Saki, catches
are made only around April when the water temperature is about 20°C„ and only
in the waters 30 = 4O miles off M^roto Saki, that iSy in the vicinity of
Taisho-bai,

(d) Schools come into Tosa Wan and are caught there in July and August„
The water temperature gets up to around 25 Co

(•) Off Kumano Nada the season for spring skipjack opens in March, is at
its peak from April to May, and ends in June, In s-ummer and autumn the
schools are greatly decreased in number, but catches continue to be made.
The schools in this area come in close to the coast and are fished in
waters 20 to 30 miles off shore from Shiomisaki to Owase when the water
temperature is about 19°Co In the peak season catches are made from 50
miles south to 100 miles southeast of Shiomisaki and activity increases
as the fish gradually come closer in to the coast of Kumano Nada^ In the
latter part of May the schools diminish and fishing ends in June„ The
average water temperature is about 19 - 22°C„

3 J Zunan area

Fishing in this area centers around the Izu Shichito, the waters
around Hachijojima and Ogasawara being especially famouSo The fishing
season begins in the Ogasawara area in February, and at Hachijojima
and Aogashima in March, the peak of the season being from April to June.
By April the fishing grounds extend to the waters off Boshu, and they
gradually shift to the Sanriku area„ Fishing grounds are found at the many
reefs within a line drawn from Aogashima south of Hachijojima through
Nishinoshima west of Ogasawara to Kita Iwojiraao

Among these fish reefs the most notable ones are Higashiba, Satomae,
and Nishlbaj all on the ftorth side of Torishima, and the waters around Sofu
Iwa, as well as Kaikataze, Kaitokuze, and Zenisu on the south side of
Nishinoshima^ These are all within the 30 to 100 fathom lineSo In this
area a distihction is drawn between sedentary skipjack and migratory fish.

The season generally begins in March or April, is at its height in
June and July, and ends around October,.

Around May in the Sofu Iwa, Aogashima, and Sumisu Shima areas the water
temperature is 20° to 22°C„ In the middle of the month the fishing grounds
shift to the westward. The peak season of the early part of May is centered
60 miles east of Hachijojima around 31° N - 139° E, and 32-33° N - 138-U0°E.
In the latter part of the month the center of the fishing grounds shifts
to the east of Izu, particularly to the waters around 33° 20' ~ 3U^ /^O'N —
1/^.0° = niC' 30" Eo Suitable water temperatures for fishing in this area
appear to be 19 - 22°Co

^8

4., Northeastern area (Sanribi area)

The schools which appeared in the Zur^an area have moved to the waters
off Inubo Saki by June,, The fishing grounds gradually extend to the waters
off Shioya Saki in Iwashiro in June and Julyy and to the waters off
Kinkazan from June to August, From August to October they extend to 500
miles off Kamaishi in Rikuchu with the fishery centered about 350 miles off
shore o Some catches are mads within 50 to 60 miles of the coast from
schools which happen to come in c5lose„

The season starts in the latter part of April around 40°N -- 14.5°Eo
The peak season is in July and August around 38'-'N -- 148'^Eo Fishing ends
in the latter part of October around 40'^N =" 14.5°Eo All of the schools
in this area are migratory fish and they are divided into what are called
ascending and descending skipjack„ Within the area they stop for a while
at one place and then swim on, The season is long, the grounds are ex-
tensive ;, and the catch is the largest of all the areao

Paragraph 3 Detection of Schools

1, Preparations for fishing

In making preparations for a trip the number of days of cruising is
determined beforehand depending upon the fishing ground which has been
selected for operation, and a number of extra days of reserve cruising
range are added to the calculations »

(a) calculation of fuel requirements, (b) preparation of provisions
and drinking water, (c) loading of icej, (d) taking on baitj (e) inspec-
tion of the hull and engine., (f) preparation of the fishing

Success in fishing is determined by the completeness of the prepara-
tions made„ This is true in other fisheries as well, but especially
minute care is essential in preparing for a skipjack fishing trip because
in this type of fishing sc many men have to work in such a small working
space. Furthermore the fishing must be done in a short space of timej
good opportunities for making a catch are extremely few,, and, as the
fortunes of the fishery direct^ it may be necessary to operate with full
efficiency for an extremely ^ort time. Consequently the preparations for
a trip must be thor&ugh- and minute »

If even one item is omitted from the preparations^, it will be im-
possible to make a good catch„ The amount and quality of the bait are
particularly vital considerations. Figuring on a scoop holding 1 ^
Z^3o97 gallons_/, a 20- ton boat will prepare 30 scoops of bait, a 50"*ton
boat 60 scoops, and a 100-ton boat about 100 scoops., The amount of bait
which is carried naturally depends on the capacity of the bait tankSj,
but for present-day skipjack boats a suitable quantity should be a
number of scoops within ten per cent of equalling the number of tons of
the vessel's displacepfr/tc With a bait tank 6" x 6" x 5"s) the capacity
to hold fish of 3c '^ ^ 4.o8 inches in length is expected to be 80 scoops of
sardines or 60 scoops of round herringo One scoop can dip up 1 to

iS

/~3o97 gallonsj^ or 800 — IjOOO sardines 3<.6 to Ao8 inches in lengthy In
actual practice shortages of bait bring about marked deviations from this
standard o

The loading of ice for preserving the fish is another point which
requires careful attention <> When temperatures are hlghj it is hard to
maintain the freshness of the catch and one would like to load as much
ice as possible, but on the other hand the result would be to reduce the
quantity of fish which could be loaded, which would not be satisfactory.
This means that it is necessary to determine just the right amount „
Allowance must first be made for loss by melting depending upon the quality
of the insulation of the fish hold and the length of the cruise., Ordinarily
a 30-ton boat carries 4- to 8 tons of ice, a 50-ton boat 10 to 20 tons,
a 70=ton boat 20 to 30 tons, a 100=ton boat 20 to 35 tons, and a boat of
around 150 tons carries 4-0 to 60 tons„ Since skipjack boats make relatively
Short cruises, they tend to skimp on iceo Particularly with the tight ice
situation which prevails in the fishing ports at present they are running
far below their minimum needs „

2, Choice of a fishing ground

When one is going to engage in skipjack fishingj one first gets a
detailed knowledge of the migrations of the schools in ordinary years, and
then one obtains data from all areas in order to be able to make an accurate
judgement of the situation and set up a sound operating policy. One then
proceeds to take the following stepSo

(A) Deciding on the area of operation

The area is determined in accordance with the seasono Once the area
is decided upon, the boat moves to the port most convenient for operations
within that area and completes all preparations for its trip. During this
time the skipper continues tc collect information from all parts of the
areao By means of reports from the fishing grounds he arrives at a
knowledge of the number of schools and the direction in which they are
heading at the time of sailing, calculates the number of days the boat will
take to reach the grounds, and decides where within the area he will fish.
It is necessary to collate the bulletins of the Fisheries Experiment
Stations, ^ae reports of the various fishing boats, one's knowledge of the
habitual movements of schools within the area, and the opinions of ex-
perienced persons, and then to proceed confidently to the area which one
judges CO be most favorable o

(B) Precautions to take on the way to the grounds

After sailing for the fishing ground which has been chosen, close
radio contact should be kept with cooperating vessels at all times and
reports should be received from the baseo Attention should be paid to
changes and indications of change in the fishing situation, and plans
should be modified accordingly^ Wien the boat approaches the scheduled
fishing ground, constant attention must be given to the water temperature
and color in an effort to find a water mass of a suitable temperature.

50

At the same time a sharp lookout must be kept for fish and every effort
must be made to discover a school at the earliest possible moment..

(C) Finding fish on the grounds

On arrival at the grounds preparations are made to be ready to fish
at any time and all hands strive to sight a school „

(1) Investigation of water temperatures

Efforts are made to discover water temperatures which are known to
be suitable at the season and in the area in order to determine the limited
extent of the fishing grounds within the broad expanse of the ocean.

(2) When the grounds being explored have been narrowed down, a feather
lure is trolled to ascertain the presence of a school,

(3) Attention is paid to the movements of sea birds on the grounds^ When
a flock is sighted, they are approached and the surface of the sea is
scanned for activity., This is because skipjack schools at the surface
are generally accompanied by flocks of birds. jVhen a flock of birds
flies wildly up and down and to the left and right at the surface of the
ocean it means that there is a school of skipjack swimming at the surface.
When a flock of birds flies high and slowly it often indicates that there
is a school of skipjack below the surface. When the birds sit quietly on
the surface it can be judged that the school is sv/imming rather deep.

The birds are an important aid to the discovery of such skipjack schools,
which the fishermen call bird-associated schools / torizuki namura /,

(/V) Schools associated with various things

(a) With whales -= Schools which accompany and live in association with
sardine whales. First sighting the great body of the whale, the boat
gradually approaches to ascertain whether or not there is an accompanying
school of skipjack. This is a method of taking advantage of the habits
of the schools,

(b) With sharks -= Skipjack schools also accompany basking sharks. By
sighting the shark the school is discovered, and this too is a method of
taking advantage of the habits of the fish,

(c) With floating logs -- Utilizing the skipjack's habit of swimming along
with a piece of wood floating in the ocean, one first detects the presence
cf driftwood and then ascertains whether or not it is accompanied by a
school,

(d) ^th sardines -- This method takes advantage of the skipjack's habit
of surrounding and concentrating a school of sardines„ A watch is kept
for the peculiar appearance of the surface of the ocean where a school of
skipjack is feeding on a school of sardines.

51

(e) Unassociated school / sunamura 7°° This type of school is discovered
by sighting the particular signs caused by the presence of the school
itselfo

(5) Times when schools can be spotted with the greatest certainty

With the fishing methods in use today it is impossible to fish after
the sun goes down. The time in which it is possible to fish is.limited to
the hours from dawn to dusk„ There has not yet been any concrete investi-
gation of the movements of skipjack schools during the night and so no
conclusions can he reached on that subject„ It is a peculiarity of the
skipjack that the schools become most active, and therefore most easily
discoverable, at dawn and at dusk (asamazume, yumazume) „ Around sunrise
in particular is the best time. Since in general more fish are taken
during the forenoon, the particularly experienced old-timers should be
put on watch then. There are quite a few of these old-timers who have an
astonishing skill in finding schools by the smell of the water and other
special signs„ That is where the factor of individual skill comes into
play in this fishery.

More catches are made in cloudy than in clear weather^ and when the
weather shows signs of changing, the chances of spotting schools are good,,

(6) Clues to the discovery of schools which bite well

Good-biting schools can be found more easily when the water is par-
ticularly clear and when the current is swift rather than slacko The
current in the open sea should be 5 ■= 6 knots and 7-8 knots near an
island. The effect of the stage of the tide is felt only near islands^
Fish living on reefs come to the surface according to the strength of the
current. In general the fish bite best at and before and after high
and low water. The calmer the sea the more the fish come to the surface
and the more opportunities there are for sighting themo The time after a
period of low atmospheric pressure is also good,

(7) Water temperatures and methods of discovering schools

If the water temperature is not suitable, the schools will not
surface even though they may be present, and it is difficult to discover
them. Each region has its standard average water temperature for each
season; when higher than average temperatures are encountered, even though
they m-iybe above the range considered favorable for fishing, the boat
Trill change its course and seek suitable temperature Sc In areas where
water masses are mingled, with sharp variations in water temperatures
clearly indicating a meeting point of currents, many good-biting schools
can be sighted even though the temperatures are not in the range usually
considered suitable for fishingo

3., The relationship between schools and the way they bite

It is not an uncoirriion experience to sight a school only to find that
the fish cannot be caught because they will not come to the bait, but it is

52

not yet possible to tell with certainty which schools will take the bait
and what sorts of schools will noto On the basis of long years of experience
and study some general predictions can be made, but the problem must wait
for further investigation. In the first place there is no scientific
standard in terms of so many fish caught per minute to determine what is
to be considered a good-biting school and what is noto Mr. Suehiro of
the Fisheries Experiment Station has indicated the following standard for
determining whether a school takes the bait well or badl/o

How well the fish bite is shown in terms of fish taken per man in 100
minutes, a figure which is represented by Q. The number of fish caught is
b, and the elapsed time in minutes is t, while the number of hooks fished
is f „ The formula is

Q

b_
tf

Q ^ 16 means poor biting
Q ^17 means good biting

This means that if one man in 100 minutes hooks 16 or fewer fishj the
school is not biting well, and if he hooks 17 or more it is a good-biting
schoolo

If we apply this formula to the actual operations of skipjack boats,
we get the following conclusicnSo Skipjack schools in the open ocean
generally bite well, and island skipjack generally bite badly. JVhen
schools which bite poorly turn up in the open sea it is usually in compara-
tively deep water„ The reason for this is explained as being related to
the supply of natural food„

(The relationship between season, weather, and time and the way the fish
bite)

In the beginning of the skipjack season the fishing grounds are for
the most part around islands and reefSo Consequently the fish do not
generally bite well because of the abundance of natural food. Toward
the end of tha season in the autumn the schools are migrating in the open
sea and the fish bite well because they lack natural food.

Table k Relation of Weather to Biting

Clear Cloudy Rain

Fog

bit well

bit poorly

number of schools

86

per cent

Ik

number of schools

30

per cent

26

105
8A

20
16

12

75

K
25

U
100

0
0

53

bit well

Table 5 Relation of Fishing Time to Biting

AsOO-8;00 a„m. 8:00 a. ra, -4-500 poin. 4.^00-10;00 p<,m.

number of schools 5^ 105 4.1

oer cent 93 77-v 79

j s 90^

bit poorly "™'^^^ of .schools 4 31/ 11

per cent 7 13 21

According to Table 4j which is based on actual operations, the fish
bite better in cloudy weather than in clear weather. The data for rain
and fog conditions are too scanty to be relied on, but they do not neces-
sarily Indicate worse conditions than prevail in clear weather. It appears
that wind force has no bearing on how the fish bite.

Table 5 shows the results of actual observations of the relationship
between the time of day and the v/ay the fish take the bait.

Paragraph 4 Catching the Fish

1, Operation of the Fishing Boat

(1) Measures taken with regard to the school

The Fisheries Experiment Station has consulted fishermen in all areas
on the question of how the boat should be maneuvered with respect to the
school in order not to lower the rate at #iich the fish bite and in order
to get the best possible catcho Their answers indicate that operations
should be conducted as follows?

(a) The boat should cut around the head of the school and throw baito
(Fukushima Prefecture, Ibaragi Prefecture, Mie Prefecture, Miyazaki
Prefecture 5 Kagcshima Prefecture) »

(b) The boat should move to the rear of the school and throw bait„ (iwate
Prefecture) „

(c) The boat should approach so that the school is up wind, (Mie Prefec-
ture) „

(d) The boat should approach so that the school is between the boat and
the sun, (Mie Prefecture, Kagoshima Prefecture).

With regard to sedentary schools which live on a reef,

(a) It makes no great difference how the boat approaches, (Kumamoto
Prefecture)

(b) The boat should appro'-ch the densest part of the school, (Miyazaki
Prefecture)

5^

These are the ways the boats are maneuvered in the various areaSj
but since (a) and (b) are contradictory no definite conclusion can be
drawn. These are customs of many years" standing j or else they are
based on the individual ideas of the fishing captains, however>, with the
development of fishing boats and especially their increased speed it is
probably necessary for each individual to decide on the approach to be
adopted in a given situation without being needlessly bound by old customSo

(2) Measures taken with regard to the method of fishing

Since ancient times there has been a regional distinction between
the two methods of fishing from the port or starboard side of the boato
If we consider the present patterns of operations in various localities,

(a) In the Kagoshiraa area cnce the school is sighted the boat heads in
the same direction as the school, bait is thrown to bring the school to
the port side, and the boat is allowed to drift with the wind on the
starboard beam^ Fishing in this way with the wind at one's back is
supposed to make the fishing lines carry out to their fullest extent and
extend the radius of operation by that much, and also to speed up the
fishing by preventing lines from getting tangled together o This method
of fishing from the port side is widily practised in western Japan„

(b) In the Shizuoka area when the school comes up to the bait, the boat- is
stopped with its starboard side downwind and the fishing is done from the
starboard side.

(0) In cases where the school is dense and the fish are biting extremely
well so that there is no danger of losing them no matter how operations
are conducted, after the approach is made by method (a) or (b) , if the
situation permits, fishing may be done from both sides of the vessel.

It is wrong to set up restrictions on operations such as is done
by methods (a) and (b) o Fishermen should be trained to respond immediately
to the school and should be able to begin fishing quickly on either side
of the boato The methods of fishing only from the port or the starboard
side are bad doctrine o

With modern skipjack boats having fishing platforms from bow to stern
and "one greatest possible number of fishermen, we should bring the schools
up to the bait skilfully so as to be able to fish from both sides of the
boato

2, Operation of the fishing gear

ll?hen the boat has approached the school and is in a position to fish
the following procedures are generally employed„

(1) Dispositic^n of personnel

In order to V^.;.n fishing the following assignment of tasks is
madeo

55

(1) Fishermen £ tsurikata_/ =•= The largest number of men are assigned
to hooking fish„ They are stationed along the fishing platform according
to their skillj the old-timers being given the positions at the bow and
stern o The most skilfull and strongest young men are stationed at the
center of the platforWo This arrangement prevents the school which is
coming in to the bait from being frightened away, and raises the efficiency
of the fishing cperation„ The other fishermen are stationed between these
two groupSo With the whole vessel ready and in the peak of conditionj,

the disposition of personnel is carefully determined as a prerequisite for
making the largest possible catch o

(2) Chummers ■=- These are the most experienced men in the crew, and
they are stationed at the bow and stern and at other strategic pointSo
Experience is needed to be able to observe the density of the school and

the way the fish bite and to know how to throw bait so as to bring the school
in to the side cf the boat and hold it there for a long time„ lien fish-
ing beginSj the bait is thrown 50 or 60 fish at a time from both the bow
and the stern on a large boat or from amidships on a small boat„ There-
after bait is thrown continuously in quantities of 5 to 10 fish at a time.

(3) Bait boys =- Inexperienced youngsters handle the job of supplying
bait to each fisherman's bait buckets The number so employed depends on
the number of men fishing.

(2) Hooking skipjack

(1) Bait fishing

(a) Baiting the hook

There are various methods of baiting the hook, all of them
designed to lower the vitality of the bait fish as little as possibleo It
is necessary that- tao ./lethod used be quick and conveniento Then the school
is biting well, th^ nook may be stuck through the back, neck, snout, eye,
or from the lower to the upper jaw of the bait fish, all of which methods
prevent the bair from swimming freely, and in rare cases a bait fishaay
even be cut in two and each half used separately, but ordinarily the hook
is stuck . -d^r the clavicle / ccracoid ij/ of the bait fisho

ib) Hooking the fish

Each of the fishermen handles one pole„ When the boat has
approached the school and bait has been thrown, the way the fish take to the
baiv Is observed^ if they take it well, the boat is completely stopped,
and the spray pump is set to spraying out sea water in order to increase
the effect of the baitc At the same time the hooked bait is dropped into
the water and allowed to swim as the pole is manipulatedo The pole is
handled in either a standing or a sitting positioHo The latter method is
customarily used ir the Kagoshima area, but it detracts from the agility
of the fisherman's aiovemer-^ s., although it does give stability to his body.
This position is suita>-'' for use when the boat is rolling violently,
but in general fishing is done from a standing position «

56

The butt of the fishing pole is planted firmly against the right thigh
and the grip is held in the right hand- The fisherman manipulates the
pole so as to make the bait swim in the watery and waits for the skip-
jack to strike^, When a fish ^ites, before it can change direction the
tip of the pole is immediately bent into the form of the character ku
/ an obtuse angle_7, and the fish is lifted up in such a way that no
slack develops in the line. The skipjack is caught under the left arm
and the hook is removed from its mouth.

There are two methods of handling the fish when they are swung in
toward the boat„ One is to catch the fish under the left arm, and the
other is to swing the fish up out of the water in an arc so that the
hook will naturally free itself when the fish is somewhere over the
fisherman's head and the fish will fall, into "the boato

(2) Fishing with artificial lures

When the skipjack are biting well, the fishermen working from the
amidships portion of the fishing platform to the stern will use artificial
lures suited to the size of the fish and the fishing conditionSo The use
of such lures saves bait, saves the time required for baiting the hook,
and increases the efficiency of the operation „ The throwing of appro-
priate quantities of bait is continued all the vrtiile so that the school
will not disperse„ When all of the fish in the school have been taken or
the fish have lost their taste for the bait and have run away, fishing
stops and the search for another school is bsguno

Fishing continues from 10 minutes to one or two hours, and sometimes
on rare occasions it lasts all da^^^ It is necessary that the crew be
ready at all times to work as a team..

It sometimes happens that from A, 000 to 5jOOG fish are taken from one
school in the space of about 30 minutes, while at other times more than an
hour may be spent in catching four or five hundred fish. With good luck
a boat may rE.':ce on a full lead of fish in one day, while other boats may
fish for ten days without filling the boat. In addition to the boat,
the personnel, and the skill with which fishing is done, the factor of
luck also plays a part in determining the differences between the catches
made by various boats,,

(3) Measures taken after the fish are caught

When the fishing of one school is finished-, the catch is packed into
che fish holds with crushed ice^ If fishing continues for a long time,
the fish are iced down whenever an opportunity offers. Every effort is
made to stow the catch as quickly as possible and to avoid leaving the
fish for very long on the deck in the heato Once the bait is used up the
bait tanks are also used as fish holds to increase the amount of fish
stowage,

(4) Notes en fishi'. gear

57

(a) Poles — Ordinarj"- fishing poles can be used on the average for
about five monthSj and short poles become useless in one months Usually
three or four pcles are kept ready for each fishermanj, and the vessel always
carries twice as many poles as there are fishermen aboardo

(b) Hooks — Each fisherman alvrays has ready large and small hooks,
five or six of each, with the leaders attached, along with a considerable
length of fishing line. A vessel going out on a trip will have ready poles
for use with artificial lures (where poles used for such fishing differ
from those used with bait) to the number of about two-thirds of the number
of crew members, m.th two or three hooks for each.

(c) Trolling hooks (searching hocks /"saguri hari 7) — Each boat will
have prepared two sets of gear and five or six hooks,

(d) Bait buckets — One for each fisherman with some extra ones.

(e) Dip nets -- Nets of various sizes are prepared for dipping bait
from the tanks, for placing it in the ready-box, and for distributing it
to the bait buckets.

@ In what respects do skipjack fishing poles differ- from ordinary

fishing poles?
@ What precautions are necessary for keeping bait fish strong?
@ What different kinds of bait fish are used for skipjack fishing?

What are the differences betv/een them?
@ Investigate the construction of bait tanks. Note their Ibcation

and size, calculate their capacity, and ask the captains how much

bait they ^vill hold„
@ When skipjack boats are leaving their base for a trip, how do they

get the necessary information on the fishing situation?
@ On what sort of data do they base their decision as to which grounds

to fish?
@ How do they find the schools on the fishing grounds? Ask the

captains about their experiences.
@ Why is '.vater sprayed on the surface of the sea when fishing for

skipjack? How do the individual fishermen work when hooking fish?

58

Chapter IV

An Examination of Skipjack Fishing Methods

Section 1 A Critique of Pole Fishing for Skipjack

Paragraph 1 Advantages and Disadvantages of Pole Fishing

From ancient times do;™ to the present day the skipjack fishery has
changed very little, and the start of the saason still sees the same brave
bustle of activity a^ all of the fishing portSo If we consider the fishery
from the point of view of methods, we find that down through the ages
there have been limited changes in the gear and, of course, in the methods
of operating the boats, but in its essentials the fishery is no different '
from what it was in ancient times. Let us try to analyze this situation
a little.

The fishing method in use at present, insofar as it applies to skip-
jack, represents an extraordinarily wonderful discovery, and admits cf no
rivalry by ooher methodSo

Contented with the results obtained by the traditional methods and
unwilling to run the risk of trying to force a change, we have fallen into
complacency and have failed to devote our energies to research. Leaving
that out of consideration for the present, let us try to investigate the
methods now in useo In the first place, the points of superiority of the
pole fishing method are the following:

(1) This method makes the best use of the habits of the skipjack. The
schools which migrate into Japanese waters are mainly hunting for food and
are in a half-starved condition^ The method takes advantage of this
fact, and by using bait which suits the taste of the fish they can easily
be taken „

(2) The schco'':^ which migrate into our waters every year are far greater
in numbers than the catch which is made, and it is the perpetual
abundance of this stock which makes it possible year after year to take
quantities of fish much greater than would be expected from the rule of
one fish to one hook which is the basic concept of pole and line fishings

(3) Tne fishing grounds are rather far out at sea, and in the past it has
been regarded as technically impossible to operate with netSo At the
present time, no method has appeared which can rival pole fishing, and the
number of vessels suitable for deep sea operations is smallo Consequently,
the fisheiy is dominated by a small number of specialized vessels which
can operate economically and profitably without forcing themselves to

any undue exertions. The natural result has been to follow the path of
least resistance ^ to neglect study and efforts to devise new methods, and
to operate on a hand to mouth basis, and this is the condition which has
obtained down to the n-er;^:nt day,, In spite of this, the fishery has,
even in the form of ios operations, reached a point of superiority high
above that of any other fishery,

59

(2^) In comparison with other fisheries, operations by this method do not
require great quantities of special materials and equipments, and the
ratio of fish caught to materials required is superior to that of any other
fishery,, Progressive changes through the years have involved only a
broadening of the scale of operations, the use of larger vessels, and an
increase in the number of fishermen in the crewSo The skipjack which are
caught are in comparatively high demandc, and with the freedom from injury
to the fish vrtiich is an advantage of pole fishing and the good degree of
freshness which is maintained, the fish also meet the demand for dried
fish-stick materials The manufacturing of dried skipjack stick has been
a positive support to the pole fishery down to the present day„

The points detailed above are thought to be the advantages of the
pole fishery for skipjack, however, if we examine these points intrinsically,
we find that they are by no means decisivec, In short, it is just a case
of nc fishery having appeared which could rival the skipjack pole fishery.
In ether words, if a better method were devised, even the skipjack pole
fishery would have to give way to ito If we inquire as to what kind of
conditians a fishery worild have to mset in order to replace the polfi fishery,
we must conclude that it would, in the first place, have to be frea of the
defects of the pole fishing methodo The points which are regarded as the
defects of this method are the following?

(a) Bait is necessary - . ^; the handling and transportation of the live bait
is extremely inconvenient,,

(b) With operations limited as they are at present to the daytime, there

is a need for an investigation of factors affecting the hours of operation,

(c) The results are controlled by the way in which the skipjack schools
take the bait„ At its worst, this factor may lead to the boat's being in
the midst of a schccv. without taking a single fisho Up to a certain point,
this fishery is axtreaiely agfp'ossivs, but it does not, after all, succeed
in escapiaf *:^?'r teiy from the category of passive fishing methodSo

The answer tr .. question of how to turn this passivity 5.nto aggressive-
ness will J- :':aDly indicate naturally what is to be the future state and
existence of the skipjack pole fishery =

Paragrap 2 Plans for Improving Pole Fishing

(1) A -xan for solving the bait problemo

As explained before, one difficulty with the fishery at present is
thf bait problem^ The skipjack season is very short in each locality and
during this short season, the beats must work to the fullest extent of
their capabilities. The fishermen may be waiting for the season to open
and then have to postpone going oxi':; to fish bscause of their inability to
get bait, or they may be out at sse. enjoying good fishing and then sE the
boats will have tc crowd back into port solely because of insufficient
baito Ihen they ory ' ' '-^siTaly over a wide expanse of

fishing grounds, th; , ., iir.a \.hdi. sudden changes in the water temperature
will kill their bait' and force them to st-op fishing. There are many ways

60

in which bait throws obstacles in the way of fishingo The solutions to
these difficulties are being studied as pressing problems in all areas,
but on a common sense basis the following suggestions are madeo

(1) Direct management of bait catching and holding.

At present, the bait supply is uneven because of the shortage of
live-pounds^ Dishonest suppliers of bait are taking advantage of this
situation and the bait supply business often falls into a state of
confusion. The following remedies are suggested:

(a) Supplying one's own baito

This method should be advantageous in large-scale operation where
three or more skipjack boats are run on a planned basiSo Bait can be
taken with small-scale gear, bait fish of the desired size can be selected
and kept, the excess can be disposed of elsewhere, and the boats can
concentrate on catching skipjack without having to worry about obtaining
baitc If lack of capital or other causes make it impossible to establish
a private bait supply set-up, a live-pound could be lent to a bait supplier
and a contract made for a steady supply of baito

(b) Dispatch of bait boats to the fishing grounds.

Bait supply boats could be stationed on the grounds 'vhere the fishing
boats are concentrated to provide a suitable supply of bait for each boat.
These vessels could also buy the catches of the fishing boats or else
take over the task of transporting the fish back to port in order to save
the time required for each fishing boat to go back and forth. This would
be one plan to increase the efficiency of operations. This method would
enable the fishing boats to seek more distant grounds and remain continu-
ously on a good fishing ground, and would open a new field for the expan-
sion of the industry. In addition to carrying bait, the boats would have
to be equipped '/dth fish holds and ice or refrigeration machinery, and they
would probably have to be prepared to supply marine supplies, fuel, pro-
visions, and so forth. This is thought to be a problem for the skipjack
fishery of the future.

(2) A step further could be taken and the skipjack fishery could be run
on a tender and fleet basis.

Section 2 Net Fishing Methods for Skipjack

A thorough consideration of the bait problem leads to the inves-
tigation of fishing methods which do not require bait. With such methods
the problem of whether or not the fish take the bait well would naturally
disappear and the restriction of operations to the daylight hours vculd
be broken through, making it possible to develop night fishing. To fish
at any time and in any place, we must consider the use of nets, parti-
cularly the purse sein^^. These have been tried out before, but in every
case, failed to produce the expected results. With a thorough cognizance
of the conditions, we should make a detailed study of the reasons for
failure and then make a fresh start,

61

Paragraph 1 Attracting Skipjack with Lights

Experiments using fishing lights to catch skipjack have not been
thoroughly gone into as yet, but we have occasionally heard of cases where
skipjack were attracted to lights which were being used to catch other
kinds of fish. There is little data to go on and it would be hard to
reach a definite conclusion, but there is a great need for further inves-
tigation on this point. The facts which we have are all from cases where
fish other than skipjack were the object of the operations and the lights
were used in waters far from the skipjack grounds. The strength of the
lights, too, was not adjusted with the object of attracting sklpjacko
In view of this, it is thought that some degree of success could be
expected from such a raethod„

(1) A report of catching skipjack by the use of lights

According to a report by MTo Umekichi Shiozaki, skipjack were
successfully attracted with lights near Uwashima in Ehime Prefecture on
August 10, 1934. o

(a) Catching skipjack by means of a purse seine

Place <, o o Near Okinoshima and Fatanarabishima in the waters off Uwashima
in Ehime Prefectiire.

Time „ « o August 10, 1934. (first day of the seventh month of the moon
calendar)

Gear „ „ <, Purse seine, 660 yards long, 132 yards deep

Lights „ 0 o Underwater lights, 24 •= 32 volts, 170 - 200 wattSo Five
lights, one per vesselo There were four light-boats and one fishing boat.
Their disposition was as shown in Fiffure 15, with the fishing boat at the
center of a square having one of the light-boats at each of the corners„
The distance from the fishing boat to the light-boats was 4.00-500 meterSo

Operation - Each boat lowered its light from 1 to 2 meters below the
surface and illuminated 6 - 7,000 tsij-bq /~TN„ 1 tsubo - 3.31 sq„ meters_7
of the sea surface. The lights were kept on from 4 to 8 hours, and as
the fish assembled the fishing boat ordered the light-boats to close in.
The light-boats slowly brought their schools of fish in to the center
and when all of the fish were assembled in one group, the light-boats
turned off their lights. The fishing boat then shot its net and surrounded
the lisho

Concentration of fish . . . Since the preceding evening, each light-boat
had been using a 32-volt 170-watt light (total 5 lights). In the beginning,
the young sardines gathered all around o After a few hours, countless
skipjack assembled. About 3s00 A.M. the boats drew in and the net was
shot. About 5s00 A.M. iirfien the lifting of the net was begun, there were

62

estimated to be more than ten thousand skipjack gathered into the bag of
the neto (Each fish weighed about 530 momme ^ 4.o38 lbSo_7) , These fish
ran about vvildlyj breaking countless large holes in the net, and by the time
the net was hauled in, most of them had eseapedo The iatch was /i.,100
fish weighing 2,173 kan (_ 11,911 IhBoJo The net was designed and operated
with the object of catching sardines, and consequently invited results of
this sorto

(2) A catch of skipjack in a four=angled lift net / ystsude aTni_7

This type of net is used in the Uwashima area for taking small mackerel-
scad, mackerel, jami. chirimen iriko„ and other small fisho It is 100
fathoms long and 25 fathoms wide and is a type of fixed gear Trtiich is
fastened to the bottomo Or.e f/ouM never dream of taking skipjack in it„
The net was operated off Asobiko near Uwashima on August 10, 1934-, the first
day of the month in the lunar calendar, by a fleet consisting of a fishing
boat and three llght-boatSo

The fishing boat used a 24=volt 120-watt underwater light, while the
light-boats used 16=volt 100-watt lights„ At first enormous quantities of
plankton assembled and in two to five minutes, ^ami gathered and swam
around under the lights^ Small mackerel- scad and mackerel began to flash
their white bellies, flyingfish cut straight across under the light, ribbon-
fish like silver snakes slid along the sides of the boats, and sardines,
squids, and balloonfish sivam about drunkenly„ At a depth of ten or more
fathoms, what appeareo to be bream were seen swimming,. After a while,
about ten fathoms deeper, large fish in numbers from several hundred to
over a thousand were seen to appear suddenly and then disappear. At
first they were taken for large mackerel-scadc As it grew later, the .laml
became densely concentrated around the lights where they swam about causing
small waves on the water. About 100 meters away, around the edge of the
lighted area, the splash of a leaping fish could be heard from time to
time„ The large fish which had shown themselves earlier were now swimming
slowly close -:& the light about 10 fathoms down„ At 2§00 A,M„, the light-
boats were crdered to close in and concentrate the fisho The fishermen
began to draw up the net slowly and gently „ Three hundred skipjack were
quite unexpectedly taken that night along with squid, mack erel= scad, j
mackerel, jamio and so forthc Other boats which fished that same night
using carbide lamps did not take any skip jack.

There are two or three other examples of the use of fishing lights,
but if we consider them all together, we can arrive at the following two
explanations.

(a) Skipjack seem to have a tendency to assemble around a light„

(b) The same result is arrived at by the skipjack's happening to gather
around the light in pursuit of the sardines which the light collects. In
other words, it is indicated that there may be a direct and an indirect
concentratior. of fish around the light.

63

These experiments make possible the following conclusions:

(a) It is possible to fish for skipjack at night„ In order to do so,
lights (underwater lights) should be used,

(b) Skipjack either school at night or may be induced to do so by using a
light «

(c) It will probably be convenient to catch skipjack which have been
attracted to a fishing light by using a purse seine or a similar type of
gear„

Paragraph 2 Purse Seining for Skipjack

Since the end of the war, with the increased propanganda for the
extension of the skipjack fishery, the use of purse seines is being
seriously studied and attempts are being made to put them into use.

Plans have been made in the past for taking skipjack with purse
seines, but they all ended in failure. There were various reasons for this,
but in general, they were the following:

(a) Insufficient research on the skipjack schools,

(b) Unsuitable gear and vessels, and a lack of seriousness in carrying
out the operation.

(c) The lack of experience on the part of the personnel in handling the
gear and the boats made experimentation almost impossible „

A fresh attack on the problem, with the correction of these conditions,
is being considered^ This will be based on the purse seine fishery for
skipjack and tuna which is achieving splendid results on the California
coasto

The California purse seine fishery is carried on by the largest and
best of the sardine purse seiners and the peak of the season is during the
three months of June, July, and August„ Since the black tuna purse seine
fishery uses the phosphorescence in the water to find the schools, dark
nights are chosen for such fishing operations. During the period 6f bright
moonli^t, the boats swiftly proceed southward, go around Cape San Lucas
at the southern tip of the peninsula of Lower California, and fish for
yellowfin and skipjack in the Gulf of California. In either case, tuna
are the principal object of the fishery and there are almost no purse
seiners which fish exclusively for skipjack.

The fishing grounds for these boats are centered around Cape San Lucas
and are divided into those within the Gulf and those on the Pacific
coast of Lower California. As soon as one rounds the Cape and enters the
Gulf, the climate changes suddenly.. Within the Gulf, the wind is generally
light and the sea is very calm. The schools are mostly mixed tuna and
skipjack and large schools of "sleepers" can be seen. It is a good ground
for tuna purse seiners and many boats operate there before the black tuna
season begins, that is dijring May, and during the light of the moon in
the regular season.

6^

Is there not some possibility of setting up a purse seine fishery for
the schools in Japanese waters like that which is so splendidly established
in America? Of course it is a question whether the form of the American
fishery can be exactly imitated in cur waters^ It is hoped that the
fishery will appear in a form suited to Japanese conditions and to Japanese
fish. Then the solution to the problems of the fishery will be found in
the use of the purse seine„ This is the problem for the future.

Section 3 Conclusion

Since the end of the war, the skipjack fishery has been under dis-
cussion from all points of view, but in every case, a tendency can be seen
to become preoccupied with mere externals without getting a full grasp of
the essentials,, Consequently,, on the following page, we have cited some
prewar statistics to serve as data for reference,

(end)

_ light /v\

rl/ — ' boats I ]

fishing boat

Q ~ boats — (J
Figure 15 Positions of light boats

0'

Note; Description of figures which have not been reproduced with the

translation because of the difficulty of copying them onto hectograph
carbon stencils.

Figure 1, A drawing of a skipjack (Katsuwonus pelamis)

Figure 9= A chr.tcgraph of three horn lures

Figure 11„ A photograph of three shell-inlaid feather lures

Figure 12„ A photograph of three small two-hook trolling lures

Figure 13, Plans of a typical large steel skipjack boat

Ua

Table 6 Tendencies of Skipjack Boats
Year Total Vessels Boats Under 20 Tons Boats Under 60 Tons Boats Over 60 Tons

192^

2,511

2,237

2^3

3

1926

2,390

2,087

2^2

6

1930

1,857

366

3^6

45

193^

1,-^69

0

216

278

193S

1,009

319

3A8

3-42

(Note) The total number of boats has diminished, but the number of those over 50
tons has multiplied 11J+ times, and the catch per boat has increased
markedly.

Table 7 Catches by Skipjack Boats Operating in Distant 'teters
Year Total Number of Fish Year Total Number of Fish

1920
1923
1926
1929

13,981,867
12,735,940
U, 408, 046
16,040,225

1932
1935
1937

14,250,971
16,524,676
25,700,944

Table 8 Vessel

Operations

by

Month!

5 for 1938

Month

Number

Number of

Larfe-est Ca

tch

Number of boats

Catch Per

of boats

Fish Taken

Tal
10,

'ing Over
.000 Fish

Boat
Z ?ish_7

April

304

461,852

8,750

OJ

1,519

May

537

1,335,663

30,700

15

2,580

June

590

1,918,734

25, 500

42

3,252

Jvly

639

3,182,314

23,207

81

4,982

August

491

1,809,359

22,050

23

3,838

September

369

1,335,108

18,666

11

6,616

66

Table 9 Catch by Areas

(According to statistical reports
of the
Ministry of Agricultiire and Forestry for 1937)

Prefecture

Number of Boats

Total Tonnage

Number of Fish
Taken

Catch Psr Boat

Shizuoka

129

10,474,33

7,122,626

55,214

Kagoshima

217

8,583o35

2,455,140

11,548

Mie

92

6,582.74

5,590,386

39,015

Miyagi

93

6,531,87

4,527,868

48,686

Kochi

152

6,084.70

1,195,864

7,581

Tolrushima

51

2,103.20

43,907

861

Kanagav.'a

25

2,065.00

177,867

7,1U

Wakayama

73

2,005,76

794, U7

10,879

Oita

57

1,892.05

3,500

61

Ibaraki

28

1,384,07

43,262

1,545

Miyazaki

60

1,575,00

432,100

8,035

Imate

36

1,497,30

305,636

8,489 ^

Chiba

2U

954.99

262,449

10,935

Fukushima

9

754,74

182,550

20,283

Tokyo

7

155.00

156,155

22,308

Ehime

17

464,93

290,300

17,079

f.1

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