ANADIAN TRANSLATION OF FISHERIES AND AQUATIC SCIENCES

No. 4914

1•113.MRY ItiND OCE •

nIt5LIOrTistQUE• " „ •, Fuf oethISS pl.7.(1n'b

Report of an ecological survey of the Steller sea lion in Hokkaido

by T. Itoo, H. Katoh, K. Wada, K. Shimazaki, and K. Arai

Original Title: Hokkaido ni okeru todo no seitai chosa hohoku

From: Geiken tsushin, January (305/6): 1-18, 1977

Translated by the Translation Bureau Multilingual Services Division

Department of the Secretary of State of Canada

Department of Fisheries and Oceans Pacific Biological Station

Nanaimo, B.C.

1983

60 pages typescript

Year Année

Issue No. Numéro Volume

Jan 305/6 1977

DATE OF PUBLICATION DATE DE PUBLICATION

Page Numbers in original Numéros des pages dans

l'original

1 - 18

Publisher - Editeur

Japanese Whaling Society, Inc.

Place of Publication Lieu de publication

Etchujima 1-3-1, Koto ku, Tokyo, Japan

Number of typed pages Nombre de pages dactylographiées

60

1008910 Translation Bureau No.

DEC - 198?

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TRANSLATION BUREAU BUREAU DES TRADUCTIONS

LIBRARY IDENTIFICATION — FICHE SIGNALÉTIQUE

c rriti-s 4/1/-1 Translated from - Traduction de

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English

Author - Auteur Tetsuro ITOO, Hidehiro KATOH, Kazuo WADA, Kenji SHIMAZAKI and

Kazutoshi ARAI

Title in English or French - Titre anglais ou français

Report of an ecological survey of the Steller sea lion in Hokkaido

Title in foreign language (Transliterate foreign characters) Titre en langue étrangère (Transcrire en caractères romains)

Hokkaido ni okeru todo no seitai chosa hohoku

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Geiken tsushin

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Whale research reports

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1008910 Japanese J.W.C. / ps DEC - 6 198e

WHALE RESEARCH REPORTS

Japanese Whaling Whale Research Tokyo, Kotoku, Society, Inc. Institute Etchujima 1 - 3 - 1

T 135 Tel Tokyo (642) 2888

pl Report of an ecological survey of the Steller sea lion

in Hokkaido1

. (I)

Tetsuro ITO°2, Hidehiro KATOH

3, Kazuo WADA

4, Kenji SHIMAZAKI

3

and Kazutoshi ARAI5 .

Fc:r

preheyi si ve_ 1. Part of a y study, "Biological research on the stocks of

Pinnipedia" partly funded by the Ministry of Education (Research representative Prof. Masaji NISHIKAWA, Ryukyu University).

2. Gifu Dental College

3. Northern Sea Fisheries Research Institute, Faculty of Fisheries, Hokkaido University.

4. Primate Research Institute, Kyoto University.

5. Faculty of Fisheries, Hokkaido University.

SEC 5-25 (Rev. 81/11)

Canacrâ

The objectives of the survey

Steller's sea lion, Eumetopias jubata (SCHREBER 1776) (1

2

Japanese

"todo") has long been known to occur in the Sea of Japan. In addition to

Allen (1880), Naumov (1933), Ognev (1935), Okada (1938), Matsuura (1943),

Ellermann and Morrison-Scott (1951), there can be mentioned the more recent

work of Nishiwaki (1972) and Geptner and Naumov (1976).

Nishiwaki and Nagasaki (1960), Nishiwaki (1965) and Nishiwaki

(1967) have given outlines of the migration, ecology and regional characteristicS

of the herds which visit Hokkaido.

Using specimens from various parts of Hokkaido, Itoo (1973) stated

that three sea areas could be distinguished in which the herds of visiting

sea lions were of differing age and sex compositions. However collections

were not made along the whole coast, so this study was both limited and

preliminary.

There are also studies made some twenty years ago of the damage

done by sea lions to the fishery, particularly by collecting the observations

of people engaged in coastal fishing, but there have been absolutely no

studies of sea lion ecology in Japan.

According to Nishiwaki (1967) and Itoo (1973) it could be considered

that the sea lions visited two sea areas, in north and south Hokkaido, with

contrasting characteristics. The objective of the survey was to clarify

many basic points about the ecology of the sea lions such as the seasons

at which they appear and disappear, their distribution,their haul-out areas,

the composition of the migrating herds, the size of the herds and their

feeding. Also included in the planning were studies of the growth, sexual

maturity, breeding, comparative morphology and parasites of captured specimens.

3

During the course of the survey many people gave us assistance.

We wish to express and record our gratitude to the following persons.

In the survey in Northern Hokkaido:-

Mr Shigeo OISHI (Rebun town, Funadomari)

Mr Yasuo OISHI (Rebun town, Funadomari)

Mr Hirota SAKANO (Rebun town, Funadomari)

Mr Binichi KURI (Rebun municipal offices)

Mr Jusuke OTSUKA (Rebun municipal offices)

Mr Takaji FUJIMOTO (Sarafutsu village, Hamaonishibetsu)

Mr Mitsutaka KURASHINA (Keio University)

In the survey in Southern Hokkaido:-

Mr Yoshietsu ARASHIDA (Usushiri Fisheries Experimental Station,

Faculty of Fisheries, Hokkaido University)

Mr Kiyoshi NOMURA (Usushiri Fisheries Experimental Station

Faculty of Fisheries, Hokkaido University)

and also all the hunters from Minamikayabe town, Birodomari, especially

Mr Ryoji KAMATA and everyone at the Northern Sea Fisheries Research

Institute of the Faculty of Fisheries of Hokkaido University.

The methods of the survey

The Northeill Hokkaido survey, which centre3around the north shore

of Rebun Island (Rebun town, Funadomari) was made in two periods, from

21 December 1975 to 13 January 1976 and from 27 February to 10 March 1976.

The Southern Hokkaido survey was made in the southwest part of Funka Bay

(Minamikayabe town) from 28 February 1976 to 22 March 1976. (Figure 1)

* Funka Bay is shown on many maps as Ushiura Bay. Translator.

ESR1FIA i* «REF N

. 4- HI MAS11111A REE F

,Z:31000 - ,tstANI

• CAPE e lIKO.T1111

FIINA »MAU BA y

Wt.% NA Ke.

AMIN MALI

lkm

FUNKA IA?

SR1RA SE

B IRQUIMA RI

ik.** UE11.11F1

13 6 ilokm

:17)

• • .•: •

T R

Figure 1

The survey areas and the places where sea lions were

captured. The * shows the places of capture, the

numbers in brackets shows the number captured.

•

Cooperation was obtained in both areas from the persons locally

concerned with sea lion destruction operations. In Northern Hokkaido six

trips were made with Mr Yasuo OISHI in his Kojumaru No. 5 - (1.5 tons) to

observe the number of individuals, the size composition and movements of

sea lions on the reefs and at sea. Following Scheffer (1967) and Allen

(1880) the measurements made on the eleven individuals captured included

the body length and thirteen other measurements and there were also

thirteen measurements of the size and weight of the internal organs,

including the gonads. The skulls and the whole skeletons were preserved

as dry specimens and the gonads, the exterior and interior parasites were

preserved as specimens hardened in 10% formalin.

The age was assessed principally from the annual ring structure

of the cementum layer and the dentine layer of No. 3 incisor in the upper

jaw10,45

. The stomach contents were investigated after hardening in

20% formalin.

Through the good offices of Mr Yasuo OISHI it was also possible

to obtain as specimens nineteen skulls captured before and after the survey

periods. The teeth and tusks of an individual captured in February 1976

were received from Mr Kiyoshi ARASHIDA, and these twenty individuals were

included as specimens for age determination.

Reference was made to the capture records (1973 to 1975) in the

Rebun town municipal offices to ascertain the numbers captured in recent

years. Sea lion hunters and others in the fisheries business were

interviewed about sea lion ecology.

6

Results and discussion

Because the number of specimens is extremely small, analyses

and discussions of the habits and movements of the sea lions, their exterior

morphology and of the data related to the weight of their interior organs,

gonads and skulls are omitted from the present report. Studies of the

exterior and interior parasites and information obtained about pinnipedia

other than sea lions are to be presented in separate reports.

1. Report of observations (Rebun)

Number of individuals on land

On trips with Mr OISHI and with local sea lion hunters, observations

were made of sea lions on land on Hirashima reef about 600 m north of Todo

Island, offshore from the northwest of Rebun Island, and the numbers were

counted with binoculars (Nikon 9x35).

The dates of observations and the numbers of individuals

were as follows:-

12 December 1975 30 - 40

28 December 1975 30 - 40

30 December 1975 71

2 January 1976 1

The reefs were assigned numbers by the authors (see Figure 2).

Observations were made on 30 December without being noticed by the sea lions

for about 15 minutes after 6.35 a.m. from the point on land marked "0" on

reef No. 4 (R - 4). The herds were resting on land and the largest total a L: a oiist- ance oF

number observed on the southern side of reef No. 2 s/ (R - 2 , local name

"uchinoshima" -"middle island") and on the southern side of reef No. 1, at .1

àieLarice. of go vyt

(R 1, "okinoshima" - "outer island") was 71.

•

7 •■■■

Hm

Figure 2

The Hirashima reefs on the north coast of Rebun Island.

(On 30 December 1975, 71 sea lions were observed on the shaded areas in the map)

R1 to R8 : The reef numbers (assigned by the authors)

0 : The observation point.

.detire,teenne›.-"".."«"""""•••

,

- --se::::•••;••

•

,

imate.,,reelle"e".›. ••• e.avé*.z:."Ys:.. • r-

Figure 3

The sea lion herd on land on the Taneshima reefs on the north coast of

Rebun Island. (Photographed by Mr Hirota SAKANO in the last third of

January 1973).

A: Part of the chain of reefs, 123 or more are on land.

B: Almost the whole of the chain of reefs, 288 or more are on land.

One tenth of the count was estimated to be missed because the

point of observation was low, about three to four metres above the sea

surface, and because all the individuals were sleeping or resting. It

was later ascertained from the tracks in the ice and snow that just the

same number of individuals were on land in the dead space on the north

side of the reefs. Thus, making something of a guess, the total number of

individuals was estimated to be about 150. None were swimming in the

nearby sea at the time of counting, and several individuals were seen on

land on the Taneshima reef about 3 km offshore which was visited about an

hour later. It was not known at either reef whether there were individuals

at sea and out of sight. There has not been sufficient study of the diurnal

activities of sea lions during the winter20

. However in this area there

are relatively large numbers on land, and according to the hunters, they

are not at this time to be found at sea.

The number of 150 is said in the interviews to be consistent with

the largest number on land in a normal year. The other three observations

were made from boats 50 m to 100 m away from the land sites, and the numbers

seen on land during eleven hunting trips from 18 December to 4 January was

70 to 80 on 20 December on Taneshima reef, so that the 71 on 30 December

is essentially the same.

Apart from our observations we received records from the same part

of the winter two years earlier which give information on the number on

land and which are presented here.

These are photographs of Taneshima which were taken during the

last third of January 1973 by Messrs. OISHI in company with Mr Hirota

SAKANO (three colour slides, 6 x 7). The number of sea lions on land was

9

counted by direct measurement of the film with a binocular microscope

(10 to 40 times). There are two films in which about four fifths of No.1

reef (local name "dohe")dere photographed from a short distance. In one

of them (Figure 3A), at least 123 were counted, and at least 129 in the

other. At least 288 were counted on Ule almost e.nire, Taneshima

reef photographed from a distance (Figure 3B).

The total number on land was estimated according to the following

assumptions. The proportion omitted in counting the film with 129+ was one

tenth. In the film with 288+ it was two tenths. (Discrimination between

individuals is more difficult in the photographs from a distance, and there

were many individuals which were asleep before the photograph was taken and

had not assumed the sea lion vigilance posture, with the head and the upper

half of the body held up to watch for dangerous objects).

To estimate the proportion of individuals in the dead spaces, it

was supposed that because of piling up on the reef the individuals in the

dead spaces of the film with 288+ would number one quarter of those counted.

The density on the back side of the reef was taken in both films to be the

same as that seen.

The densities on all reefs were taken to be the same as those found

in the film with 129+ and the film with 288

+ for reef No. 1, and the areas

of the other five reefs were found, neglecting reef No. 7 on which sea lions

were not believed to land. The area of reef No. 1 and the total areas of

reefs Nos. 1 to 6 were determined from an enlarged drawing (Figure 5) of

the air navigation chart (HO - 73 - 7Y, Rebun) and the ratio was taken as

the multiplier

+ 288 film: 288

+ x 2/10 x 5/4 x 2 = 864

+

+ 129 film: 129

+ x 11/10 x 2 x 90/36 = 709.5

+

10

These are extremely rough estimates, but if there is significance

in the near equality of the two numbers, there will be no great error in

thinking that the number on land on the whole of the Taneshima reefs on

that day was from 700 to 900. In conjunction with testimony from the

hunters that "there were none on land on the Hirashima reefs on that day

and no sea lions were seen swimming in the nearby sea" and that "so many

were seen on land only once in several years" one may think that in many

years the size of the herd wintering along the north coast of Rebun Island

is less than 1000. To estimate the total number visiting during the winter

would require data on the individuals arriving and leaving and this is not

possible in the present survey.

The individual composition of the herd

The size composition of the herd seen on 30 December was such that

large adult males accounted for at least 80%. One specimen, No. 75-K-6,

which was shot at the end of the period of observation, was estimated to

be 9 years old. There were some medium size individuals which were slim

from neck to shoulder (adult females or young males), and there were two bv, out,1-- bort lasE year.)

small individualewhose body length from the head to the stomach was about

half that of the adult males and were estimated to weigh about one tenth

the weight of an adult male. One of these small individuals was lying by

the water's edge ventrally touching a medium size individual, and from

their activities these two appeared to be mother and child.

On 25 December the sea lions were forced into the sea from the l or s■vo i‘uur.S

Hirashima reefs by shooting and were pursueefor trophies at sea with a

boat. Even when chased by the boat they did not immediately disperse but

11

continued to swim in groups of two to ten. It was possible to ascertain

the size composition during this by the relationship between the size of

the heads and upper half of the body which could be seen above the water

and the colour of the fur.

I) Adult males. Large size and thick neck. The profile from

forehead to snout is a concave curve, which is a noticeable

characteristic. Many are light brown but some are light grey.

II) Medium size individuals. Evidently smaller than I. The

neck is narrow and slim. When the upper part of the body is

seen out of the water this characteristic clearlydiscriminates

from I. They are believed to be almost all adult females but

may perhaps include young males. The fur is brown strongly

tinged with black.

III) Small individuals. Even smaller than II. The fur appears

jet black. They are probaby one to two years old.

Of these three, the proportion of I was overwhelmingly high, and

Of III extremely small.

From these observations on land and at sea, the composition of

the herd visiting the north shore of Rebun Island in the latter part of

December 1975 was over 80% adult males, about 10% medium size individuals,

and in addition a small number of individuals one to two years old.

This result probably confirms the herd composition in the Rishiri

and Rebun regions reported by Nishiwaki (1965) and Nishiwaki (1967).

12

2. Methods of capture and numbers captured in recent years

North coast of Rebun Island

Sea lions are hunted from December to the following May as a

joint enterprise of the Northern Rebun Island Funadomari Fisheries

Cooperative and the Funadomari branch of the Rebun town municipal office

(the budget for 1975 being 800.000 yen). Hunters with licences to

destroy noxious birds and animals are paid a bounty for each animal caught,

but do not use specially designed boats. There has been no destruction

in the south from Kafuka since 1974.

Sea lion destruction operations commence on the Taneshima and

Hirashima reefs when the sea lions arrive in November or December and

continue until they disappear from the area about April. The most prolific

season is late December to late January.

Sea lions are shot with rifles, and there are three methods of

hunting. These are "okauchi" (hill hunting), "mizuuchi" (water hunting)

and "funauchi" (boat hunting). In the "hill hunting" method the hunters

go stealthily ashore when the sea lions are on land and shoot at short

range. This is the most efficient method from December to January when

there are many sea lions on land. In the "water hunting" method sea lions

on land, on the reef or swimming in shallow water close to the shore are

shot from behind the rocks, and in the "boat hunting" method sea lions at

sea are chased into shallow water by small boats and are there cornered

and shot.

After February there are few sea lions ashore, and since the

transparency of the coastal water is lowered after the middle of the month

it becomes especially difficult to detect sea lions which have sunk after

13

being killed, so that the effectiveness of all methods is reduced. There

are no restrictions on the methods of hunting to be used, so that the

method used in each hunting trip is changed at will as may be expedient.

There is a very strong tendency on the north shore of Rebun Island

to hunt large individuals selectively. The reasons for this include "the

fact that the large ones make the easiest targets and have the greatest

weight of meat" for since Rebun is a remote island the seal meat has not

until recently been discarded but has been preserved as food. They also

include the hunters' eagerness "to get a large trophy". Consequently the

group of individuals taken does not correctly reflect the composition of

the natural herd and is almost restricted to the adult males (see below).

It is said that over a number of years the greatest damage was

done here by sea lions in 1972. According to the records of Funadomari

branch of the Rebun town municipal office, total numbers killed in 1973

to 1975, including the number captured and the number killed but not

recovered, are shown in Table 1.

The annual kill number can be seen to be practically constant at

50. If the size of the visiting herd is about 1000 as stated above for

late January 1973, the kill in 1973 was about 5%. Since the visiting herds

in 1974-1975 were certainly smaller than in 1973, the kill rate may be

taken to have been greater.

Of this total kill, 90% was due to Mr OISHI's hunting group.

The exact dates of capture in 1974 and 1975 were known from his diary.

These are shown by thirds of the month in Table 2. The individuals

captured were all males.

48

51

43

Period 1974-1975 1975-1976

December middle third 4 2

last third 5 5

Table 1

Recent scores in sea lion hunting operations in Rebun1

.

Hunting season Total number killed

February to April 1974

December 1974 to March 1975

December 1975 to February 1976

1. Rebun municipal office records

2. Total number captured or killed but not recovered.

Table 2

The number of sea lions taken in each third of a month

in recent years by the Rebun Island hunting group

Number captured

14

January first third 4 2

middle third 2 , 1

last third 11 • 10 .

February first third 2

middle third 4

Totals 26 26

15

Both years agree in that the peak in the number captured is found

in the last third of January. The probable reasons for this include the

land habits of the sea lions (see below), and the effect of the weather

conditions on hunting trips (trips in small boats, landing on the sea

lion reefs governed by sea conditions, especially wave height). This

peak in capture must also be strongly related to the peak in the

number visiting.

South-west shore of Funka Bay

According to an enquiry (1975, unpublished) concerning sea lions

made by the Northern Fisheries Research Station of the Faculty of Fisheriesm

Hokkaido University, six of the ten fishery cooperatives in the southern

part of Funka Bay have a policy of destroying sea lions.

About ten persons are licenced to destroy destructive birds and

animals in Birodomari, Minamiyakabe town, the survey area in the south of

Hokkaido. The sea lions begin to appear in November and December, and the

hunting season is from late December to the middle of May. The period of

most abundance is from early February to early March. There are no sea

lion haul-out places in the south-west part of Funka Bay and the hunt

always takes place at sea about 500 m offshore.

The number captured from December 1975 to March 1976 was 14, all

of them males, and in 1974 it was 20, including 2 females. In 1973,

about 70 were taken, including 3 females of which one was pregnant, the

others were males. Thus the most recent annual mean is about 40.

UNEDTD T

A :

16

3. The age and sex composition of the individuals captured

Eleven sea lions were captured during the period of the survey,

five at Rebun and six in Funka Bay. Figure 1 shows the places of capture werc

and Table 3 the external measurements. Twenty others ''captured in the

same areas before or after the survey period (nineteen at Rebun, one in

Funlça Bay were added), and the results ordetermining the ages of these

thirty one specimens, all of which were males, are shown in Table 4.

The 24 from Rebun Island are 24 of the 26 shown for 1975 in

Table 2 and were all captured during the main season (late December to late

January). All except one of the 7 captured in Kinka Bay were taken in the

latter half of the main season from late February to late March.

All those from Rebun Island were captured one or two at a time

to thin out the herd on the reefs, those from Funka Bay were captured at

random from the herds of one to several swimming offshore.

Turning to the age composition it is seen that at Rebun Island

88.5% were adult males five or more years old which had reached sexual

maturity38

and 54.5% of these adults were older individuals of nine years

or more (individuals reaching social maturity50

). Only 11.5% were immature,

and these three immature individuals (two-year olds), were small and were

captured when showing trust in the hunters. p6

In the proportion of adult males this age composition of sea lions

at Rebun Island is close to the results of visual observation by Itoo (1973)

which have already been mentioned and in which all fourteen were males of

These percentages are as given in the text, though I cannot make them agree with Table 4. Translator.

H) 0

5-1 4-t E

al 0 -4) A P. H 0

0

g-i

O. 00. -P -r-1

g-1 E • S-1 4-.) 4-1 Q. 0 g-1 0.0 0.0 CH 0 0

CIO 0.bO O bO 15 • IC 0 CO 15

4-40 0 0 4-. M CI-4

4-) 4-) -P 4-, 4-) (Q 4-) e O 0 W (fl R. 0 g-f g-1 • g-1

Ç34) Ç4

E 0

O M O E 0. m z

0.1 cn 8

ndy

leng

th Location of capture

South-west shore of Funka Bay

76-1 1976 2 28 8 : 00

76-2 1976 2 28 8 : 00

76-3 1976 3 3 9 : 00

76-4 1976 3 4 9 : 15

76-5 1976 3 14 8 : 15

76-6 1976 3 22 8:30

Yasuuchi offshore at.; 2 211 128 60 49 86

Yasuuchi offshore 3 222 142 60 53 96

Iwato offshore 5 265 166 83 63 113

Futami offshore 8 298 205 86 63 121

Birodomari offshore ,'» 3 223 147 76 53 101

Birodomari offshore 5 259 178 79 52 119

North shore of Rebun Island

75K5 1975 12 24 7 : 30 Taneshima inshore 5 262 — 86 60

75K6 1975 12 30 6 : 53 Hirashima reef 9 300 — 96 63.5

75K7 1975 12 30 7 : 15 Hirashima inshore 6 268 — 95 62.5

75K8 1976 1 .1 7 : 30 Hirashima reef 7 257 207 93 62

75K9 1976 1 4 7 : 30 Hirashima reef 15 286 223 102 66

Table 3

Measurements (in cm) of sea lions captured in Funka Bay and at Rebun Island

.•

,■■■

..1■1,

■1,

.1■1,

•■•

3

■.

3

3

2

2

4

1

2

2

1

1

Table 4

Age composition of sea lions captured in Funka Bay

and at Rebun Island

Age South-west shore North shore Funka Bay Rebun Island

Feb - Mar 1976 Dec 1975 - Feb 1976

2 1

3 2

4 1

5 2

6

7

8 1

9

10

12

13

15

17

Total 7 24

18

19

five years or more. However it differs with regard to the absence of medium

size individuals. Consequently it is biased towards old age as compared

with the age composition of the natural herd.

The Funka Bay specimens included four immature individuals of

four years or less and three adults of five years or more. Of the 23

included in Itoo's (1973) results for this area, one was an adult female,

the remainder being all males of which more than 70% were immature. Thus

females were extremely rare, and these results evidently agree with the

present results in the great excess of immature males over females. diverj en c_e_ be_weevi

The above account shows a s.e the seasons for collection are

limited, that there are questions about the methods of capture used at Rebun

Island, and that the number of specimens from Funka Bay is extremely small.

Comparison of the compositions of the separate herds of sea lions which

visit the two areas would be premature, but if the attempt must be made,

they are seen to agree on the rarity of females and to differ in that there

is a high proportion of adult males at Rebun , but a high proportion of

immature individuals in Funka Bay.

4. Survey of the stomach contents.

After the weight of the stomach contents had been measured they

were classified into fish skeleton specimens and cephalopod jaw and mouth

parts as was done by Hotta (1961), Matsubara (1955), Svetovidov (1948) and

Watenabe (1955). In order to compare the degree of digestion of the

stomach contents they were recorded on a digestion scale of 1 to 5, following

Wada (1971). In order to make comparisons of the weight ingested by each

individual, the weight of the stomach content was expressed as the

(Stomach content weight) x 10

5

(Body weight) 3 ■•■•. Index

stomach contents weight index

20

Feeding habits

The results of the analyses of the contents of the sea lion

stomachs are shown in Table 5.

Funka Bay

The stomach contents included the following four species

Smooth lumpsucker Aptocyclus ventricosus

Walleye pollock (bigeye) Theragra chalcogramma

Sculpins Gymnocanthus sp.

Giant octopus Paroctopus dofleini dofleini

Lumpsuckers were found in all individuals. The lumpsucker is known

to approach the coast to spawn from winter to spring, to be sluggish in AS

movements and to have ventral adhesive discs. The morphologies of the males

and of the females differ. In normal years, fishing in the southern Punks Bay starts in late January.

Where it was possible to measure the exterior morphology of the ()LÀkIcl_

lumpsuckers the average body length'was 27.00 cm and the average

weight was 1109 g. The females in the contents contained many eggs.

One bigeye was found. Digestion was advanced and only bones were

found but the lower gill cover bone of the bigeye is distinctive and

identification is easy. The length of the otolith found in the stomach

content was 20 mm which is taken to imply a body length of 380 to 420 mm

(Hokkaido Regional Fisheries Research Laboratory, 1973).

A-,

-p

weight in

dex

4-1 CO 0

Cll .0 -H E Z

Notes bD

0 3 D

iges

tion in

dex

Stomach

contents

Food species o

• 0 --- 0 E g-f -Poe

aica 0.0 W ES-1 • E • c 0 -p— m c (I)

1 20

many 5,840

1

21+

8,440

1

100.0

99.2

0.8

20.0

80.0

100.0

98.2

1.8

91.0

9.0

97.4

0.4

2.2

Stones (250, 7 g) Fish net

Stones(365,250) (160 g )

Stones(270,230 g)

Table 5

Stomach contents of sea lions captured in Funka Bay and at Rebun Island (1975 - 1976, winter)

76-1 4,770 50.8

76-2 8,670 79.2

76-3 5,450 29.3

76-4 21,340 80.6

76-5 13,080 117.9

76_6 22,790 131.2

75K5 21,180 117.8

75K6 Empty 0 75 1(7 5,860 30.4

751(8 8,440 49.1 75K9 T 0

Funaka Bay Smooth lumpsucker Giant octopus Smooth lumpsucker Sculpins

Walleye pollock (bigeye) Giant octopus Smooth lumpsucker Giant octopus Smooth lumpsucker Smooth lumpsucker Giant octopus Smooth lumpsucker Giant octopus

Rebun Island Atka mackerel Smooth lumpsucker Giant octopus

Atka mackerel Sand lance Sculpins

Smooth lumpsucker Giant octopus

(ilptocgc.lu4 ventnico4u4) (Panoctopu4 doe,Ceini doeteini) (AptocycLu4 ventn-Lco41/4) (§ymnocanthilA 4p.) (Thenagna chatcogmfmmz) (Panoctopu4 doeteini doelein£) (4/3-toceci_u4 ventnico4u4) (Panoctopu4 doeteinL doeteini) (Aptocecla4 ventnicoAaA) (Aptocec-CuA ventnicoAuA) (PanoctopuA doeieini doeteini) (Aptocyc2.114 vent7ico4u4) (Panoctopu4 doeCeini doeteimL)

(Pieuno9nammu4 4p.) (Aptocecitm ventn)coAuAl (Panoctopu4 de-Lei/1i deleiai)

(i-Ceunognammu4 Ap.) (AinmodeteA pen4onatuA) (Cottidae) (Aptocgc-LA ventnico4u4) (Panoctopu4 dofieiai deleini)

10+

4,770 2

2 T 5

18+

8,600 2

1 70 4

2 T 5

2 T 5

2 1,095 2

1 4,335 1

30+

21,340 2

16+

12,850 1

3 230 3

18 20,730 2

1 2,060 1

61+

20,640 2

1 80 3

1 460 3

Stone (880 g) 4 0.3

3 99.7

5

2-3 100.0 Stone (232 g) 5 - Stone (335 g)

Stomach content weight index = (Stomach content weight)

x 105

(Body weight) 3

Percentage by weight of each type of food, excluding stones, etc.

T: Trace

22

In late February to March the spawning season of the bigeye is

already over and they are moving offshore to search for food. This is

thought to be why the sea lion stomachs contained little bigeye.

One sculpin was found. This species lives throughout the year

in a zone close to the coast.

Five giant octopuses were found. Cephalopocb are rapidly digested

but the beaks, the eyeballs, and the soft shells (of squids) are often

found present as remnants in the stomach contents of normal pinnipeds.

Thus when pieces of flesh are found, it may be supposed that the time

elapsed since they were caught and eaten is relatively short.

Large quantities of giant octopus flesh were found in sea lion

specimens 76 - 3 and 76 - 6 and the shape of the arms could be distinguished.

In 76- 6 in particular the tentacles and head were complete, so obviously

the sea lion was captured immediately after catching and eating the octopus.

Apart from food, stones were obtained from 76 - 2, 76 - 5 and

76 - 6, and nylontex fish net was obtained from 76 - 2. The net was

believed to have been used to catch lumpsuckers.

The weights of the stomach contents of the six sea lions were from

4770 g (76 - 1) to 22790g (76 - 6). Expressing these as the stomach content

weight index shows the approximate trend of the quantity of food eaten

(ranging from 29.3 in 76 - 3 to 131.2 in 76 - 6). The degree of digestion

in 76 - 6 was low (1 to 2) so that the diminution of the weight of the

contents was relatively small.

These values may be considered as standards with which to estimate

the weight of food eaten by a sea lion.

23

None of the six was found to have an empty stomach. According

to Spalding (1964b) few empty stomachs appear among the sea lions of British

Columbia 1.5 hours after sunrise, but are most frequent after 17.5 hours.

The quantity of stomach contents is also greatest at 1.5 hours after sun-

rise, averaging 1750 cc, but smallest and practically 0 cc at 15.5 hours.

This must be considered to show that food catching activity is vigorously

undertaken from midnight to early morning.

It is not known whether or not the Funka Bay sea lions have a

similar diurnal feeding habit, and the conditiors of the survey in British

Columbia were quite different, but all the six individuals were taken

between 8 a.m. and 9.30 a.m. and this is thought to have affected the

reasons why no empty stomachs were found.

Rebun Island.

In contrast to the specimens from Funka Bay, the weights of the

stomach contents were small except for one individual (75 K 5) and two

individuals were empty. This is thought to be affected by the fact that

the sea lions were not taken at sea as they were in Funka Bay but on land

while resting (75 K 6, 75 K 8, 75 K 9).

The stomach contents included five species:-

Smooth lumpsucker Aptocyclus ventricosus

Atka mackerel Pleurogrammus sp.

Sand lance Ammodytes personatus

Sculpins Cottidae

Giant octopus Paroctopus dofleini dofleini

Bigeye bones were also found in vomit collected at the landing sites.

24

Lumpsuckers were found in two individuals, and nine with relatively

clear external morphology had an average length of 23.3 cm and weight

317 g. Compared with Funka Bay the weights were extremely light. This

may be thought to be due to the difference between the survey seasons

(two to three months) and to the fact that there were many males at Rebun P8

Island and the females had eggs which were not completely mature.

Atka mackerel were found in two individuals. Both Pleurogrammus

azonus and Pleurogrammus monopterygius occur in this area and their remains -

are difficult to distinguish in the stomach contents so they are recorded

as Pleurogrammus sp. 75 K 5 had caught at least 60, and their size was

found to be about 30 cm. The Pleurogrammus found in 75 K 7 had a

reconstructed length of 32.6 cm (from the tip of the skull to the caudal

fin bone).

Sand lances were found in one individual but the number was uncertain.

Sculpins were likewise found in one individual but the species

could not be determined.

Giant octopus were found in two individuals. In 75 K 5 there was

a large tentacle 67 cm long, in 75 K 9 only a beak was found.

The following deductions can be made from the stomach contents of

the eleven sea lions caught in Funka Bay and at Rebun Island.

The stomach contents of the sea lions were composed of fish and

cephalopods, predominantly lumpsuckers and octopus. Large quantities oflump- diA:4-re n c.e in

suckers were being eaten in both areas, with no effect due tcithe survey season.

This is thought to suggest that there is some relation between the

habits of the lumpsuckers and the sea lion migrations. The sea lion diet

tended to include items which were coastal, were spawning near the shore

or were bottom-dwelling.

Books

1) van Bree, P.J.H. 1976. On the correct Latin name of the

Indus susu (Cetacea, Platanistoidea). Bull. Zool. Mus.

Univ. Amsterdam, 5(17)1139-140.

2) Einarsson, S.T. and E. Jonsson. 1976. Nahveli blaupa Zi land

i nagrenni Reykjavikur. Natturufraedrngnrinn, 46(1-2)

22-24.

Perrin, W.F. J.M. Coe and J.R. Zweifel, 1976. Growth and

reproduction of the spotted porpoise, Stenella attenuata,

in the offshore eastern tropical Pacific. Fish. Bull.

74(2):229-269.

4) Perrin, W.F. 1976. First record of the melon-headed whale,

Peponocephala electra, in the eastern Pacific, with a

summary of world distribution. Fish. Bull. 74(2)1457-458.

5) Kenyon, K.W. 1977. Caribean Monk seal extinct. J. Mamm.

.58(1):97-98.

6) Brown, S.G. 1977. Twenty-eighth meeting of the International

Whaling Commission, 1976. Polar Records, 18(115):386-388.

7) Anonymo”s, 1977. Porpoises school mon in sonar technology.

Australian Fish. 36(2)26.

8) Anonymous, 1977.. Antarctic seal at home in Coffs Harbour.

Australian Fish. 36(2):27.

9) Anonymous; 1977. River dolphin protected. Fishini News

Inter. 16.(6):13.

* This list occurs here in the text and is consequently included though it appears not to be connected with the main article.

Translator.

25

3 )

26

WHALE RESEARCH REPORTS

No. 306 February 1977

Japanese Whaling Whale Research Tokyo, Kotoku Society, Inc. Institute Etchujima 1 - 3 - 1

T 135

Report of an ecological survey of the Steller sea lion

in Hokkaido (II)

Tetsuro ITOO, Hidehiro KATOH, Kazuo WADA, Kenji SHIRAZAKI

and Kazutoshi ARAI.

5. Survey of interviews (Rebun)

Introduction

As is true of all pinnipeds living in Hokkaido, there have been

no studies of the ecology of sea lions in this region, and sea lions are

extremely difficult animals for researchers to collect.

The hunters have obtained knowledge of how to obtain their

catches by means which differ from those of the researchers, but there is

no doubt that this is just the knowledge which must be accumulated in

order to make any catch.

In this survey of interviews we have endeavoured to deduce the

ecologically distinctive characteristics, particularly the regional

characteristics, of the animal in question from the knowledge which has

;

TR

e - z t%1

27

historically been accumulated. At the present stage of our studies it is

even essential to acquire such preliminary but complementary knowledge.

It was felt that in the present state of study of pinnipeds in

Japan the interviews obtained during the past years form something which

could not be omitted from the survey, and it was decided to record an

outline of the content of these interviews.

In keeping with the character of this report, all matters concerning

the movements and mode of life of individuals have been omitted.

The following persons were interviewed during the survey. We are

deeply grateful to each of them for this cooperation.

Mr Shigeo OISHI (Rebun town Funadomari, fisherman, sea lion yasuo oist-ii ( Same, Sanla, born 1944 ),

hunter, born 1918)‘,"Mr Hirota SAKANO (Rebun town Funadomari, iron works

manager, born 1918), Mr Yoichiro SAITO (Rebun town Funadomari, former sea

lion hunter. born 1901),Mr Tomiyoshi SASAKI (Rebun town Nishiuedomari,

fisherman, born 1901), Mr Setaro SETOGAWA (Rebun town Funadomari, fisherman,

sea lion hunter, born 1911), Mr Yukio SAKANO (Rebun town, former head of

the town council), Mr Jingoro KAMATA (Rebun town, Kafukafunbe, fisherman,

sea lion hunter, born 1919), Mr Takaji FUJIMOTO (Soya county, Sarafutsu

village, Onishibetsu, fisherman, born 1935).

Coastal Ecology

The inshore migration route

The migration route of the sea lions which appear annually on the

north shore of Rebun Island from the end of November to the beginning of

December and leave at the end of April is thought "to follow the increase

and decrease of the drift ice on the shores of the Kurile Island and

Okhotsk Sea, making a round trip between those areas and Rebun Island"

1113 ite do Mara:

■2;kix.r4k i

AJove* bt,e N

1)ectow4f./1_

liEnceeet. . DNI

etedffli

ki&e.45,4,

re_edr)4 .:1•-•

i5af.4kr.: 14- , igice .•\1•3- ,„\,

ic.fitke L414 Mel‘i

Ci.ne 13e,i. ■ *

&to. of 7Ixéc,,,

0 10ko:

Figure 4

Distribution and migration of sea lions in winter and spring

on the shores of Rishiri and Rebun

Dotted areas : Areas in which sea lion herds are frequently observed

H : Haul-out places

DH : Abandoned haul-out places

H1 : Taneshima reef

H2 : Hirashima reef

H3 : Neko rocks

DH1 ; Todo (Sea lion) Island

DH2 : Tataki Island

DH3 : Cape Gorota

DH4 : Bukkoda (the name of a coask)

Arrows : Directions of migration

28

F.1

29

and there is no known connection between Rebun Island and more southerly

parts of Hokkaido.

Concerning the route by which the herd goes north, it was observed

50 to 60 years ago that "the herd which departed from the Taneshima reef

off Rebun Island went by way of Moneron Island offshore from south-west

Sakhalin (former Japanese Todo Island, 46°15'N, 141 °15'E, about 90 km off

Cape Sukoton, the northern tip of Rebun Island)".

It is also said that "sea lions which now cross annually at the

beginning of May from the south shore of Rebun Island to the north shore

of Rishiri Island congregate in an area two to three miles offshore from

Cape Fuji to Oshidomari, where they form a large herd and depart northward".

These two stories are of course conjectures but they probably indicate

the ends of the migratory routes (Figure 4).

Seasonal abundance and disappearance in coastal areas

Firstly we discuss conditions from Cape Sukoton to Taneshima reef

(Figure 4 and Table 6). As already stated, "the season of arrival is late

November to early December. The season of abundance is late December to

late January, when almost all are adult males with a few adult females

and young. At this season they haul out on the Taneshima and Hirashima

reefs. In a normal year the maximum number on land is about 150". The

total visiting number is thought to be greater than the number on land,

but no estimate has been made.

"There are no sea lions hauled out after February and the number

seen at sea near the haul-out reefs diminishes". Causes for this are the y

known dispersals to neighbouring areas aneMigration to Rishiri Island,

Now Now

December

February

Late May

October

April to May

June

0 0

Off North coast Vicinity of of Rishiri Island Todo Island reef

1 1

February to March

0

October to May

0

Yes Yes

Table 6

Comparison of sea lion ecologies on the shores of Hokkaido

Locality North shore Rebun Island

South shore Rebun Island

Hamaonishibetsu coast

Period

Time of arrival

Time of most abundance

Time of disappearance

Number of summer residents and composition

Number of haul-out places

Haul-out period

Number of rookeries

Assembly areas before going north

Damage to useful fish or fishing gear

50 years ago

(present all year)

May

(2/3 disappear in May)

1/3 of winter number,mainly young animals

more than 6

October to May

1

Vicinity of Taneshima reef

No

Now

Late November to early December

Late December to late January

Late April

0

2

December to January

0

None

Yes

31

but it is thought that an immediate cause is the sea lion hunting,

particularly the "okauchi" (hunting from behind the rocks), which is

continuous from the first arrival.

"The composition of an individual herd gradually changes from

February to April, and the proportion of females and young increases. In

April the number of young individuals increases to more than in February

and March but at the end of April almost all disappear and it is rare to

see a young one in May".

It was found that the ecology of the sea lions forty to fifty

years ago differed from the present ecology in the following ways (Table 6).

"At that time they hauled out during the period of most intense

cold in January and February, and the number hauled out did not diminish

at the beginning of February as it does now. The season with the greatest

number hauled out was when the sea lions began to gather together on

Taneshima reef in May before going north, and the season of abundance was

not in December or January as it now is". As mentioned above, at present

the area for gathering together is probably on the north coast of Rishiri.

"Nowadays they disappear at the end of April, but at that time

small and medium sized individuals to a number of about one third of those

present in the winter remained in this area during the summer after the

herd had left for the north".

On the coastal area of the southern end of Rebun Island, "they

arrive in December, the number of individuals is greatest in February, and

the herd then contains several tens. At the end of May herds of 30 to 40

each are formed and move over to the north shore of Rishiri, and in June

they become extremely rare, only one or two being seen".

32

The distribution along the coast

It is thought that "the place where the sea lions first arrive

is, without exception, the Taneshima reef, and from there they disperse

to other coast lines among the islands" (Figure 4).

"The visiting season lasts from December to the end of April

and the distribution density is greater on the west coast of Rebun Island

than on the east coast, but the areas in which the sea lions are often

observed in a herding situation are restricted. The places in which there

are many sea lions are, in order,

1) The area extending from Taneshima and Hirashima reefs to Todo

Island and as far as Cape Sukoton (called, below, the NW area). In this

area there are from several tens to a hundred and several tens.

2) In the area on the south coast of Rebun Island offshore from the

Neko coast extending from Chiyuka to Cape Karannai (the S area) there are

from around ten to several tens of individuals.

3) In the NE area off Cape Kanedano in the north east of Rebun

Island there are from several to several tens of individuals.

In addition herds of a few to several tens of individuals are

found in the neighbourhood of the two capes at Nishiuedomari on the west

coast and on the reefs by the gathering places on the north east coast

of Kafuka".

It is believed that these herds are all "gathered together while pll

resting". Concerning the feeding areas "large herds appear in December

to January in a six mile area off the west coast from Uennai to Motochi

and in a three to four mile area of Cape Uedomari on the east coast, which

are the fishing areas for Atka mackerel (Pleurogrammus) and bigeye (Theragra)"

Figure 4.

33

From these conditions of distribution, it is thought that "the

centre of the distribution of sea lions on the coast of Rebun Island is

the NW area, which has haul-out places and storm-time refuge places (see

below), and small migrations from there are repeatedly made to the feeding

areas". There are small scale haul -out places in the S and NE areas

and it is thought that "houses are rare at the ends of the capes and under

the cliffs and the sea lions can evade disturbance by humans or by fishing

boats and rest for a while" but "the NW area provides sufficient haul-out

and rest places". In addition, at Cape Gorota, Cape Sukoton, the Amanna

beach north of Utomai and other places of similar beach topography "there

are often several sea lions sleeping or resting at sea, especially in the

early morning" and hunters from coasts other than the NW area where there

are no haul-out places have always caught these sea lions by "mizuuchi"

(hunting from boats).

It is also said that "herds at the gathering places will come

to eat fish thrown overboard from fishing boats returning to the port

of Kafuka".

The haul-out reefs and their characteristics

The Taneshima reefs consist of seven reefs lying directly north

to south, all of them narrow and extending from south west to north east

(Figure 5). The first and northernmost reef (R-1, local name "Dohe") is

the largest (about 90 m by 30 m). The island about 60 m north of Reef

No. 1 (Okinoshima) is for some unknown reason not included in Taneshima.

"Among these, the favourite haul-out places for sea lions are

Reef No. 1 and Reef No. 2 (R-2, "Nagashima"). The north east of the former

o

34

1- o

Figure 5

The principal sea lion haul-out places on the Taneshima reefs,

(A and B) and the rookery about 50 years ago (A).

R1 to R7 are the reef numbers (authors' nomenclature).

ï

0 54

Figure 6

The principal sea lion haul-out places on the Hirashima reefs, (A and B)

R1 to R8 are the reef numbers

For C and D see the text.

35

is high and the south west is low. The centre of the south west part is

concave. In contrast the north east part of R-2 is low. The sea lions

prefer to haul out on the concave part of R-1, their next preference being

the north-east of R-2. (Points A and B in Figure 5). When there are

many sea lions those which,do not manage to haul out on these two reefs

haul out on the other reefs Nos. 4 and 5. (The haul-out conditions in

Figure 3 form an example of this).

"In March and April of a normal year, there may exceptionally be

a few hauled out on No. 4 only".

The Hirashima reefs consist of eight reefs in an almost circular

cluster about 150 m north to south and about 130 m east to west, located

about 600 m to the north of the centre of a bay on the north shore of

Todo Island. "Of these, those on which the sea lions haul out are mostly

restricted to reef No. 1 (Okinoshima, R-1) and reef No. 2 (Nakanoshima, R-2).

Both of these are about 40 m east to west and 30 m or 20 m north to south.

.(Figure 6).

"Like reef No. 1 at Taneshima, the western half of reef No. 1 here

is concave and the sea lions like to haul out there (point A). When there

are many individuals they haul out on the high part (about 3 m) on the

eastern side. On reef No. 2 point B to the east is normally used. Reef

No. 4 is used only when Nos. 1 and 2 are covered with individuals already

hauled-out".

"In March to April one or two individuals haul out at point C on

reef No. 8. Point D was used for hauling out in the winter several year

ago but recently it has not been used".

Moreover, for unknown reasons "For about 5 years from 10 years

ago to 5 years ago, no sea lions hauled out on any of the Hirashima reefs".

36

These "ways in which the haul-out places are chosen have not

changed on the Taneshima and Hirashima reefs from 50 years ago" and the

surfaces of the rocks in the haul-but areas of the reefs much used by

the sea lions are smooth (authors' observation). The reason for the

constant use of the same areas is thought to be that they satisfy the

following requirements - - "a distinct topography providing places from

which the approach of men or boats can easily be seen, deep water next to

the rocks so that the sea lions can dive in their preferred response to

an emergency, and shelter from wind and waves".

The centre of distribution of sea lions on the shores of Rebun

Island is considered to be in the NW area from Taneshima Reefs to Cape

Sukoton. An important condition for this is probably that in addition

to containing the two haul-out reefs "the topography of the coast of Todo

Island within easy reach from the Hirashima reefs has the shape of a

letter H with the lower right tip missing, and provides locations which

are excellently protected, not only from the prevailing north west wind

but from severe waves from all directions".

Another haul-out place is the Neko beach near the south west tip

of Rebun Island (about 4 km south of Motochi). It was often observed that

"sea lions have hauled-out here since about 1975 and in the same months of

the following year, February to March 1976, there have continually been

from 4 - 5 to 10 sea lions hauled out there".

On the eastern shore "there are occasional haul-outs on the shore

of Kitousu" but it is not certain that these haul-outs are to be confirmed

(it is believed that sea lions will occasionally haul out here_ ancLUier in (-21e.

37

early morning and at times when fishing boats are not around on shores

away from habitation).

Further it is said that "independent individuals may haul out

at quite unusual places, but they are usually wounded or ill".

"There used to be normal haul-out areas on the west shore of

Todo Island and on Tataki Island (a reef about 150 m south west of Todo

Island)" but they are not used at present. According to Mr SAITO who lives

on Cape Sukoton the sea lions he caught "were almost all taken on Tataki

Island (Figure 4, DH2) and hunting trips were rarely made to Hirashima and

Taneshima reefs as they are now". (According to tradition, the origin of

the name Tataki was "the name given by the Japanese who saw the Ainu hitting

(Japanese "tataki") seals and sea lions with clubs).

Also "large numbers of sea lions climbed up the steep slopes to

haul out on the large reef at the end of Cape Gorota" according to

observations made about 60 years ago, and there is evidence that the sand

beach in the centre of Hamanaka Bay (local name Bukkoda) was the scene of

special sea lion hunts with nets in 1914 to 1915 so one may suppose that

this point was a haul-out area. However sea lions rarely haul out on

that beach nowadays.

Former breeding records

It was generally agreed between fishermen and hunters in Rebun

town, Hamanaka, that sea lions used to give birth on Taneshima reefs. The

"History of Rebun" (1972) states that according to data obtained by the

Agriculture Development Faculty of the University of Tokyo in 1963 "sea

lions were giving birth to pups (p 42), but the date is not recorded.

38

Interviews with old-time hunters and other observers convinced us of the

actuality of breeding up to 1926.

It is believed that there are no existing reports of sea lion

rookeries on the shores of the Sea of Japan, so the contents of the

interviews are reported here with slight abridgements.

I. Mr Tomiyoshi SASAKI's stories

First story

About 20 May 1923, Mr Sasaki, then 18 years old, accompanied his

father and elder brother to fish with nets for lumpsuckers in the sea near

the Taneshima reefs. Sea lion parents and pups were found on the SW part

of reef No. 1 (Figure 5, point A). There was a "makabu" (a name used for

a particularly large adult male, now obsolete) with a length from nose

tip to edge of rear flipper of 1 go 2 - 2 shaku (364 to 394 cm), six or

seven adult females, 8 to 9 shaku (242 - 273 cm) and six pups, 3 to 4 shaku

(91 - 121 cm). Five of the pups were held in the mothers' flippers as they

escaped to sea, the remaining pup fell between the rocks and was captured

by the Sasaki party. This pup was rather smaller than the others with a

body length of about 1 m, its fur had regions of a more reddish colour,

and it had an umbilical cord about 2 to 3 sun (5.1 to 7.6 cm) long. On

the homeward journey the mother chased the boat, (which had two pairs of

oars) and bit repeatedly at the oars which were of evergreen oak. By the Eue. cajeS cq. 211.

time Todo Island was reached veight oars had been c..11eweci away. The

captured pup was fed for about 50 days but it was eventually eaten.

Second story

In the summers of 1915 and 1916 mother sea lions and pups were

seen playing together just as dog puppies play on land on the reef

furthest offshore of the small chain of reefs stretching NNE from Cape p13

39

Sukoton (Manju rock). The mothers swam around in the vicinity and did

not attack. At that time such la- born pups were called unibankon

(second pups).

Third story

In the latter part of July 1920 or 1921 five or six sea lions

were observed to be accompanied by pups in the sea close to Todo Island.

One of them was swimming with the pup riding on its back.

II. Mr Yoichiro TSUSHIMA's story

Mr Tsushima, a fisherman who was born in 1897 and who died in

1963 told the following story about 1953 to Mr Yukio SAKANO.

While harvesting funori (glue-plant, Gloiopeltis furcata) one

densely foggy morning in May, Mr Tsushima who was then in his teens went

on a pleasure trip in a small rowing boat with a fishing crew of three

young people about 30 or 40 minutes from Todo Island towards Taneshima

reefs to catch sea lion pups. Because of the thick fog they lost their

way and were not able to get to Taneshima. They wandered around all day

at sea, and finally just managed to arrive late at night at Awabikotan

(on the north west coast of Rebun Island) and were able to take refuge in

a house.

This is the story of a failure but it can be taken at least to

show that at that time many trips were made to capture sea lion pups

which were normally easy to capture.

III. Mr Yoichiro SAITO's story

After 1921 Mr Saito fished for herring and kelp at Cape Sukoton

and Todo Island and also incidentally killed sea lions. (When he stopped

hunting sea lions in 1945 his total kill was about 70).

40

When he wasa child in the latter part of the Meiji era and during

the Taisho era (i.e roughly the first quarter of the present century), sea

lions gave birth on Taneshima reefs, but no breeding activity has been

seen since 1928. Births were practically restricted to the hollow places

on the south west of the northernmost reef No. 1 (point A, Figure 5), and ree Fs or ori

there were no births onvHirashima Island, Todo Island or Tataki Island.

He thinks that the birth season was May to June, but fishing was

very busy after the middle of May and he is not certain.

The largest number of pups observed was about ten. The migrant

labourers who came from inland ("nishin no wakamono" - the herring laddies")

would frequently go out to catch a pup which would be 2 shaku 5 sun to

3 shaku long (73 to 91 cm) and would amuse themselves by making it swim

around while tied to a rope.

Around the time directly before the sea lions gathered together

on Taneshima began to go north thirty to forty would be resting hcre. avlcl

ol the shoals and reefs, and they included the extremely large adult males 1K viorma/ years,

which were called "makabu". v hese makabu did not appear until the time Lc) L7c1i

for going north, and vto one tried.' them (they were 1 jo 3 - 5 shaku (394

to 455 cm) long and their flesh is said not to have been eaten because it

had a very offensive odour). The makabu were often observed to fight among

themselves, leaping violently out of the sea and biting at the upper parts

of their bodies. Blood would frequently flow from necks and shoulders and

many new and old scars were often found in those parts. At haul-out time

the makabu would take up positions on the highest rocks and would normally

keep their heads up even when the other sea lions were sleeping. When

humans approached they were the last to rush away.

41

In the Meiji and Taisho eras (i.e. before about 1926) the

individuals hauled out on land did not rush headlong into the sea at one

gunshot, as they do now, and even after two or three gunshots most of

them remained asleep. However one reason for not giving birth on

Taneshima was the disturbance produced by the annual capture of pups.

At that time part of the herd which had left Taneshima for the

north hauled out at Moneron Island (also called Todo Island, i.e. Sea in Sakkalin

Lion Island) vand it was once observed that a large number of sea lions

were born there.

A study of the content of these stories

1) The season when breeding occurred

Verifiable memory of observations of pups on Taneshima dates

only from 1923, but however one regards the evidence of Mr SAITO, the best

informed of the three informants, there can be no doubt that breeding

regularly occurred from about 1910 to about 1928. No pups have been seen

since 1933 - 1934 when Mr SETOGAWA began hunting, and it may be supposed

that breeding had stopped about the beginning of the Showa era (1926).

2) The season of birth

The occurrence of birth in mid May to June agrees with reports

on the birth season in.America and Canada3

'24

'39

'42

and on the birth

season in the Kurile Islands4. It is very likely that the births on

lake.

Manju Island were exceptionally births in an exceptional locality in that area.

3) The place of birth

Among the several haul-out places of the period, the place of birth

was restricted to reef No. 1 at Taneshima, which is very interesting because

42

it is the place most used by sea lions both then and now. One may suppose

that the conditions required of a birth place are more numerous than those

required of a haul-out place.

4) The size of the breeding herd

All informants agree that the size of the breeding herd was

extremely small. Examples of breeding in such small herds are not other-

wise known4,39

, and this is thought to be very unusual. The harem

structure (6 to 7 cows to one bull) agrees with the ratio already reported39,47

.

5) The size of the new-born pups

The sizes given in the stories are all estimates and memories

of estimates so they may not be of great significance even though they

agree with known data (89 - 122 cm, average 100 cm23,24,42,45).

In this

region in particular it is customary to express the length of adults as

from the tip of the nose to the end of the rear flipper, so the estimates

for pups may be too small.

6) Parent-child relations

There are no existing reports of actions such as the cows holding

pups by the front flippers when escaping, a cow robbed of her pup chasing

and attacking the boat and a pup riding on the back of a swimming cow, but

they could be anticipated from the actions of other pinnipeds.

7) The reason for abandoning breeding

According to the History of Rebun (1972) advances in motive

power of the boats (p 522) at the beginning of the Showa era (the middle

1920's) caused changes in the character of the herring fishery during the

main fishing season (p 444), but this is not believed to be directly

p14

43

related to the abandonment of the rookeries. Mr SAITO's suggestion "there

was no breeding because of the disturbance produced by hordes of people"

may be appropriate. Even at the present time the haul-out place is

disturbed by hunting every day of fine weather after December, and in the

past there were probably similar occurrences when, according to the story

on page 31 (page 10 of the Japanese text) the sea lions used to haul out

and gather together on the reefs in February.

8) The bio-geographical situation of the rookery

Apart from the observation by Mr SAITO there is an observation

made by Mr Jingoro KAMATA's father about breeding on Moneron Island in

Sakhalin "there were so many sea lions that there was nowhere left to

set foot on the shore. The sea lion pups had no fear of man". This suggests

that Moneron Island was a fâilrly large scale rookery.

Metaphorically, one might wonder whether Taneshima may have been

a "branch store" of this Moneron rookery.

Voronev (1974) has reported the occurrence of sea lions on Moneron

Island, but breeding there is not believed to have been previously reported.

Bobrinskii (1944) reported a sea lion rookery at Vladivostok but

this is not a very recent report, and since Geptner and Naumov (1976) do

not mention it, the report may not be accurate.

Thè'southérnmost rookery at present known in the Okhotsk Sea and

the Kurile Islands is that reported on the southern tip of Etorofu Island

by MIYATAKE (1943). Recently, according to Belkin (1966) and Perlov (1970)

this is a haul-out place for young adults and the southernmost rookery is

the south of Chirihoi Island (Brat Chirpoev).

44

Thus there are places which have been lost, but the first rookery

known to have existed on the shore of the Sea of Japan was at Taneshima

reef. This would make it interesting to know whether there is still a

rookery on Moneron Island.

6. A preliminary survey at Hamaonishibetsu, Soya county

Hamaonishibetsu in Sarafutsu village is not far from either Rebun

or Rishiri Islands and is visited by many sea lions during the winter.

Moreover there is a sea lion haul-out reef (Todo Island, or Sea Lion Island)

only 1.5 km from the main island, and this is expected to present a

favourable location for ecological studies of sea lions.

A comprehensive study of the ecology of sea lions will probably

require knowledge of the migrations which link the rookeries in Soviet

territory to Hokkaido and also the movements between the haul-out places

and the assembly places and their utilization throughout Hokkaido.

With this in mind a preliminary survey was made on 9 and 10 March

1976 of the present conditions at Hamaonishibetsu where the circumstances

mentioned above are present.

Results of the investigation

Through the courtesy of Mr Takaji FUJIMOTO, we went out in a small

boat to observe the sea lions on Todo Island, and observations of the total

number were made for about 30 minutes on the morning of 10 March, starting

at 6.20 a.m.

Todo Island is formed of two reefs of almost equal area. A

maximum of 86 was counted on the south west sides of the two reefs (the

Hokkaido side). In addition, 101 could be counted on a slide-film photo-

graph taken by our companion Mr Mitsutake KURASHINA.

45

An estimate based on the topography of the reefs and the situation

of the sea lions on land suggested that the total number hauled out was

1.5 times as many (130 to 150).

The size structure of the individuals on land was taken from the

same film by Mr KURASHINA and divided into the standard sizes previously

used, large individuals, medium individuals and small individuals, with

the results shown in Table 7.

• About one half were large, one quarter medium and there were only

a few small individuals.

More individuals were seen at sea than were hauled out on the

reefs and there were more medium and small individuals than large individuals.

In contrast with the structure described above on the North shore

of Rebun Island in late December, it was thought that medium and small

individuals were more common than large individuals in both the hauled-out

and swimming herds.

Stories

Mr FUJIMOTO told us the following stories about the ecology of

sea lions at Hamaonishibetsu.

"Sea lions appear every year in this area in October, and haul

out on Todo Island from November. The number of individuals is greatest

from April to May (about 500). The maximum number hauled out is of the p15

order of 150, and this is composed of large individuals. There is no room

for small individuals and they gather together at sea".

"The season during which they stay is from October to May. During

this time there is no change in size structure, with medium and small

being 20% to 30% of the large size".

Table 7

The number and size structure of sea lions found hauled out

on the reefs (Todo Island) at Hamaonishibetsu, Soya county 1.

Ree2

Large3

Medium4

Small5

f

Unknown Total name size size size size

Reef No. 1 32 18 3 12 65

(19.2) (27.7) (4.6) (18.5) (100)

Reef No. 2 19 9 1 7 36

(52.8) (25.0) (2.8) (19.4) (100)

Totals 51 27 4 19 101

(50.5) (26.7) (4.0) (18.1) (100)

1: 10 March 1976

2: Authors' nomenclature

3: Adult males

4: Adult females and young males

5: One year olds

( ) Percentages

46

. 47

"They start to go north in May and in June they have disappeared.

(Table 6).

"No sea lions can be seen when drift ice covers all the sea and

touches the shore, but when the drift ice moves away they are to be seen

immediately. Abnormally, the drift ice did not touch the shore even once

from the end of 1975 to 10 March 1976".

About 25 km from Hamaonishibetsu "they may haul out on Benten

Island on the south side of Cape Soya during rough weather when they cannot

haul out on Todo Island. There are no haul out places on shore to the

south east in the direction of Esashi. It is thought that the Nijo shore

(45o47'N, 142

o14'E) on Soviet territory, about 48 km NNW of Hamaonishibetsu

is used as a main haul-out place from Todo Island".

"Sea lions damage nets set for salmon. Five years ago Mr Koichi

SHIBUTA (Mombetsu) hunted sea lions at the request of the local fisheries

cooperative. During the year he killed about 100".

General discussion

This survey was on a very small scale (about 1.515 million yen)

but it will no doubt be valuable as the first study officially initiated

of Japanese pinnipeds, which, except for a survey of the fur seals made

long ago on the basis of an international treaty, have been completely

neglected.

All over the world studies of sea lions in winter have lagged far

behind summer (breeding season) studies20,44

48

Sea lion migrations are known in the following areas -

Central California3,6,7,11,36

, Oregon22

, the Aleutian archipelago and the

east coast of the Bering Sea20

, and the Commander Islands2

'12

However the characteristics of the migration depend on the area

and do not agree with the Hokkaido pattern of arrival in October to

December and departure in April to May. If one looks carefully for some

point of seasonal agreement, it may perhaps be found in the movement

between Kamchatka and the Commander Islands of the herd which contains

the main body of the young males. This herd is to be found in the

Commander Islands in winter from October to March and disappears in April.

Or there is the herd of adult males and half grown males with no females

which goes north in summer and migrates south to the Aleutian Archipelago

in late autumn just as the ice arrives.

These studies of sea lion migration in foreign countries are in

general made by observation of the increases and decreases of the numbers

in rookeries and haul-out areas and of the directions of swimming and

migration at sea, and surveys of specimens taken from specified areas

during the winter are completely lacking.

Consequently nothing now exists which can be directly compared

with the very modest data concerning the ecology of the wintering herd

which we obtained in our survey.

There were differences in the amount of effort we expended on

interviews on the north and south coasts of Rebun Island and at Hamaonishibetsu,

and we cannot say that it was enough for the two latter places, but we wish

to mention some pointswhich we think should be subjects for later studies.

49

1) The date of arrival at Hamaonishibetsu is about one month earlier ((.5thoi, r)

than on the north and south shores of Rebun Island, and the date of

departure is about one month later (May to June), and they are the same

at Rebun south shore, Rishiri south shore and formerly (40 to 50 years ago)

at Rebun north shore. The former main season at Rebun north shore (May)

was the same April to May, but now it is greatly different on the north

shore (December to January) and on the south shore (February). It is a

very interesting point that the present season at Hamaonishibetsu is very

similar to the former season on the Rebun north shore, except that none

remain after June (Table 6).

The geographical and temporal variations of the times of

appearance, prevalence and disappearance and the simultaneous changes in

the herd assembly and the migration routes are phenomena connected to the

increase and decrease of rookeries and haul-out places. One may suppose

that in order to understand the changes in sea lion ecology on the coastal

areas of Hokkaido it will be necessary to analyse the long period climatic

changes and the related changes in the animals used for food, and also the

increases in fishing activities (especially in winter) which have occurred

for at least twenty and perhaps up to fifty years.

2) While the sea lions remain at Rebun Island (December to April) they

haul out on the reefs in the north but are believed to tour all the

coastal areas (from Taneshima reef to Soya Island is about 26 km) and at

the end of May they are said to cross the Rebun strait (about 10 km) to

the north coast of Rishiri Island. At Hamaonishibetsu they are known to

respond to the state of the sea by moving to Cape Soya (about 25 km) and

to the Nijo coast in Soviet territorg (about 48 km).

p16 p16

50

Taking these movements into consideration, it may be conjectured

that there will be movement to and from Rebun and Rishiri Islands to Cape

Noshappu and Cape Soya, in the direction of Todo Island at Hamaonishibetsu

and even further to Yagishiri and Teuri Islands (about 75 km from Rishiri

Island) and to the Soviet Moneron Island (about 90 km from Taneshima reef).

Consequently elucidation of the ecology of sea lions in the

Hokkaido area will require a survey throughout a wide area from Mombetsu

to Cape Soya to Rumoi to determine the movements of sea lions inside this area.

Next we wish to say a word about the character of the present survey.

In both north and south Hokkaido the survey was completely dependent

on the sea lion destruction business (the restricted sea lion hunting by

means of small boats or beach boats). These are suitable if the objective

is a sea lion hunt but even if there is an opportunity to ride with them

satisfactory time for observation and counting cannot be guaranteed.

Moreover, since sea lion hunting combines aspects of recreational fishing,

recreational hunting and net profit, it is suspended as soon as the

numbers hauled out or coming to the local hunting area decrease, and there

is no possibility of making trips to neighbouring areas or of searching

offshore.

Some advance should be made in the relations between researchers,

fishermen and hunters concerning damage to nets and fish, which at present

is limited to exchange of examples. The researchers should include the

demand for the reduction and disappearance of sea lion damage in their

long term programme but the research activities and the destruction

business complement each other and at first they should probably remain

independent. The future survey will have no plans in this direction and

will be content with restricted results.

51

*

4

For more than 20 years in the USA and Canada, and more recently

in the Soviet Union, aircraft have been used to take censuses of pinnipeds

including sea lions, and they are now regarded as the conventional

means 8,20,25,39,40,46

. One of the most important subjects is the

determination of population sizes for resource studies, and it is considered

to be close to impossible to do so by accumulating small surveys such as

this. Studies of pinnipeds in Japan suffer from great handicaps concerning

funding, research organization and research personnel, and we would like

in this report to list in a few simple phrases the studies which we

consider necessary to make sea lions the centre about which this lost

opportunity can be regained.

1) A survey of the sea lion distribution in the entire area of the Hokkaiso coast21 line (survey of the state of distribution of the waters where the sea lions congregate and of the reefs on which they haul out, and more particularly a study of the state of use and of the conditions of location of the haul-out reefs)

2) Studies of the social ecology of sea lions during the non-breeding

season. (This is an area which is as yet untouched, not only for sea lions

but for other pinnipedia. Studies at selected haul-out reefs of the

seasonal and annual changes of the number and of the composition of the

herd and of the organization of the herd and the relations between the

individuals. Naturally the use of marking and telemetry should be considered).

3) Surveys of the feeding habits and the food animals of sea lions and

studies of the actual damage caused by sea lions. (At present no data

have been accumulated which researchers can use on the actual damage. This

should be combined with studies of sea lion feeding. At the same time it

will be necessary to find out the historical changes in coastal fishing

activities and the ways in which sea lions have become harmful. A

prerequisite will be cooperation between the research organization and

the sea lion destruction business).

52

4) A survey of the number of sea lions which visit all areas of the

coast of Hokkaido. (Based on studies Nos. 1, 2 and 3, the most effective

method will be simultaneous surveys by all means from boats and aircraft

and on land of the number visiting during the winter and spring periods)

5) A coordinated study by means of a survey (research) vessel. (The

Hokkaido coast would be divided into three or four areas and a vessel of

30 to 100 tons would be used for three to five years for the ecology

(herd composition, breeding circumstances, feeding, etc.), morphology

(aquatic adaption, growth),physiàogy and other basic studies. In this way

the characteristics of the Hokkaido coast as the southern limit of the

sea lion migration area will become known).

6) An oceanological study, centered on the ecology of pinnipeds and fish

in the Okhotsk Sea, the Sea of Japan and the North Pacific Ocean (a long-

term joint study by Japan, USSR, Korea, Canada and USA). This should make

it possible to understand the whole life history of sea lions, including

their migration).

' -I

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