MORPHOMETRY, GROWTH, AND AGE OF TUNAS

Marine Biological Labor , to*,-

L I E K A X^ -y

JUN 1910..'^^

WOODS HOLE. Mj\^;S.

SPECIAL SCIENTIFIC REPORT: FISHERIES No. 22

UNITED STATES DEPARTMENT OF THE INTERIOR FISH AND WILDLIFE SERVICE

MORPHOMETRY, GROWTH, AND AGE OF TUNAS

Marine Biological Lab^r toiy

L X B K .A Xi -y

WOODS HOLE, .V-'i'S.

SPECIAL SCIENTIFIC REPORT: FISHERIES No. 22

UNITED STATES DEPARTMENT OF THE INTERIOR FISH AND WILDLIFE SERVICE

Explanatory Note

The series embodies results of investigations, usually of restricted soope, intended to aid or direct management or utilization pi^ctices and as guides for adminiatrative or legislative aotion. It is issued in limited quantities for the official use of Federal, State or cooperating agencies and in processed form for economy and to avoid delay in publication.

Washington, D. C» May 1960

United States Departaent of the Interior Osoar L* Chapman, Secretary Fish and Wildlife Service 'Albert M, Day, Director

Special Scientific Report - Fisheries No. 22

MORFHOJTETRY, GROWTH, AND AGE OF TUNAS

Translated from the Japanese language by

SCAP translators and W. G. Van Campen

Edited by

B» M* Shimada

and

W. G. Van Campen Pacific Oceanic Fishery Investigations

CONTENTS

Preface Page

1. Measurements of yelloirfin tuna fropi the Equatorial

Counter current Area, By Kenzo Ikebe _l/» ••• 1

2» The correlation between the length and weight of yellowfin

tuna. By Hitoshi Hiratsuka and Seiichi Mori _2/, . 8

3, Grovrth curves of blue-fin tuna and yellow-fin tuna based

on the catches near Shigedera on the West Coast of the

Province of Izu, By Kinosuke Kimui-a 3/«.» 11

4» Four papers on the morphometry and age o7 tropical tunas.

By Kenz? Ikebe _4/ 17

On the age of yellowfin tuna from Palau waters ••.••••• 17

Measurements and ages of tuna from Palau waters .20

Measurements of yellowfin tuna from south of the Marshalls , • 23

On the measurements of albacore and yellowfin tuna from

Saipan waters ....•26

\J From South Sea Fishery News [Nanyo Suisan Joho], Vol. 5, No. 3, pp. 5-13.

June 25, 1941. 2/ From the Formosan Fisheries ^'agazine [Taiwan Suisan Zasshi], No. 241,

pp. 8-10, 1935. 3/ From the Bulletin of the Japanese Society of Scientific Fisheries,

[Nippon Suisangakkai Shi], Vol. 1, No, 1, May 1932, V From the South Sea Fishery News, Vol, 3, No. 10., Vol. 4, No. 1,

Vol, 4, No, 2, Vol. 4, No. 5, respectively.

Measurements of Yellowfin Tuna from the Equatorial Countercurrent Area

The writer has previously reported in this journal how he measured yellow- fin tuna (taken on longlines) from Palau waters and determined their ac^es by consulting an ape-length table. The majority of the tuna taken were in their seventh year; eightii-year and sixth-year fish were next most numerous.

Past fishery investigations have shown that fish in their fourth year, and some as young as the second year, are caught near the islan'is (the so-called "resident fish"), but the yellowfin which migrate continually in the currents of th« open sea have rarely been found to be younger than the fourth year.

Although these facts were obtained from the results of a survey conducted in the waters off Palau, they coincided in general with those obtained in the later survey carried out in the waters south of the Marshall Islands.

Since it was thought that it would be possible to get a general knowledge of the morphometry of yellowfin tuna inhabiting the South Sea area by conduct- ing a survey midway between the two archipelagoes, that is, in the waters south of Truk, Ponape, Kusaie and Jaluit islands, we waited for an opportunity to gather data in that area. When at a later date the survey ship Zuih3'Maru car- ried out fishing ground surveys in that area, we measured the yellowfin taken there. The results of these measurements are compiled in this article.

As seen under the coliamn heading of current direction, every one of the grounds surveyed at that time is shown to be in the area of easterly currents. We can definitely assume from this fact that the fishing grormds were within the Equatorial Countero'urrent. The title of this article therefore, can be justified.

The data contained in the tables which follow can be stinmariEed as f ollows j

Table 1

out of 2

fth-j th-j

Table 2

Table 3

out of 11

out of 9

out of 12*

(TN.

1-year fish -year fish /7jbh to 8th-year l7th-year fish |6th to 7th year Iffth-year fish ^th-year fish 7th-year fish '6 th to 7 th -year 6th-year fish pth to 8th-year yth-year fish (sth to 6th-year ^Presumed to be out of 14 with 5th to 6th-year fi

/^th-year fish 7th to 8th-year 7th-year fish 6th to 7th-year 6th-year fish 5th to 6th-year 5th-year fish 7th to 8th-year 7th-year fish

6th-year fish "th to 7th-year

Table 5

out of 61

Table 6

out of 22

fish fish

fish

fish

fish sh 6)

fish

fish

fish

fish

fish

1 1

3 4 2 2 2 5 1 1 1 7 5*

1

4

38

2

8

5

3

2

17

3 2

/7th to 8th-/ear fish 1

\7th-year fish 36

m t-i o * ^ /Lc* 6th to 7th-/oar fish U

Table 8 oat of 65* 6th-yeir fish 18

5th to 6th-year fish 5 ».5th-year fish 1 (TN. »Pre3umed to be out of 66 with 7th-year fish 37)

The majority of the yellowfin caught in this area were in their seventh year; next most numerous were 8th-year and 6th-year fish. The data clearly indicate that yellowfin under the i^th-year wei^ not caught.

I took great pains in measuring these yellowfin in order to learn the age of the fish taken tfj tuna longlines in island waters. Although this was the objective, I felt n\y interest mount as I accumulated more and more measurements for I was able to obtain strong evidence of the permanent nature of the tuna fishing industry of the islands,

BrieTly, the fact that the tuna longline, which is the principal gear used in tuna fishing, takes only the mature yellowfin and does not catch those below the 4.th-year or those which are immature means that the fishery is conducted according to the natural law of spawning protection. (Although young and imma- ture yellowfin are sometimes caught in the waters near the island, such in- stances are rare and insignificant.) For this reason, I believe that the stock of this tuna species is of a permanent nature.

(May 23)

-2-

TABLE 1

No.

1 2

Date 3f Catch

11- u

Pishing Ground Position

U5°13'E

Current Current Direction Speed

E/S

0,A

Length (Centimeter)

118 107

Abight (Kan)

8.000 6.500

Sex

female

Year of

Age

7th 6th

TN: 1 kaji = 8.27 lb3«

TABLE 2

	Dat,e of	Fishing	Current	Current	Length	7feight		Year
No.	Catch	Ground Position	Direction	Speed	(Centimeter)	• (Kan)	Sex	of Age
		^'^IS'N
1	11-15	U6"23'E	E/S	1.0	131	llcOO	female	7th- 3th
2	n	II	It	ft	130	10.500	It	7th
3	n	M	n	It	lU	8.000	n	6th
U	K	n	n	n	113	8.500	ti	6th-7tl-
5	n	n	It	It	115	8,000	II	6th
6	n	n	n	It	128	11 o 500	male	7th
7	II	rt	n	II	128	11.900	n	7th-8th
8	n	ti	It	II	121	11.900	female	7th-8th
9	n	n	It	n	12A	10.200	n	7th
10	n	It	n	tt	127	10.600	male	7th

TABLE 3

p===	Date of	Fishing	Cunrent	Current	Length	Weight		Year
No.	Catch	Ground Position	Direction	Speed	(Centimeter)	(1^)	Sex	of Age
		5°28»N
1	11-20	151*^29 'E	SE/E	0.2	125	10.500	male	7th
2	n	It	It	It	125	10.500	ft	7th
3	n	it	n	It	137	10 o 500	female	7th
A	n	n	It	11	133	12«000	male	8th
5	It	n	It	n	118	9o000	female	7th
b	n	r.	It	It	123	10,500	male	7th
7	n	tt	It	It	lU	7.500	It	6th
8	It	n	n	It	135	13.^0	It	8th
9	tt	II	n	II	120	7.900	female	6th-7th

				TABLE U
	Date of	Fishing	Current	Current	Length	IVeight		Year
Noo	Catch	Ground Position	Direction	Sneed	(Centimeter)	(Kan)	Sex	of Age
		3°56'N
1	11=21	1 52050 'E	E	-=	124	10 c. 700	male	7th
2	II	n	rt		129	10.000	II	7th
3	II	n	II		105	5.100	ferrale	5th-6th
K	II	II	fl		105	5.200	rt	5th-6th
5	II	II	II		135	11.100	male	7th-8th
6	n	ti	II		123	9.100	n	7th
7	II	Fl	(1		127	10c 000	n	7th
8	n	II	If		119	8.200	It	7th
9	n	II 11		105	5.600	It	5th-6th
10	11	II	II		123	10 „ 000	It	7th
11	11	II	II		127	10.000	n	7th
12	11	It	It		102	5cOOO	female	5th-6th
13	II	It	11		106	5»200	male	5th-6th
U	n	II	n	101	A =600	It	5th-6th

			TABLE	5
	Date of	Fishing	Current Cxirrent	I«ngth	Weight		Tear
No.	Catch	Ground Position	Direction Speed	(Centimeter)	(Kan)	Sex	of Ace
		2030 *N
1	11-22	154°20 «E	ENE	112	7.000	female	6th
2	n	n	•1	117	8„000	II	7th
3	It	II	11	111	6.800	male	6th
U	n	It	It	119	10,000	female	7th
5	II	It	n	96	^c500	male	5th
6	It	It	It	1?1	10c 400	It	7th
7	n	It	It	102	9.100	II	6th.7th
8	If	n	It	127	8.900	female	7th
9	If	II	11	VU,	9o300	II	7th
10	n	n	It	108	5o500	male	5th-6th
11	n	It	II	123	8„500	female	7th
12	It	It	n	123	9.000	male	7th
13	II	n	It	U2	7.600	female	6th
U	II	It	It	119	9.300	It	7th
15	n	II	It	128	10.000	male	7th
16	II	II	It	138	11,000	n	7th-8th
17	n	II	n	125	8.600	It	7th
18	It	II	It	127	10.100	It	7th
19	n	II	It	127	9,200	It	7th
20	II	II	It	119	8.500	female	7th
21	It	It	II	105	5,500	male	5th-6th
22	II	n	It	125	9.700	II	7th
23	It	11	It	105	5.300	It	5th-6th
•2J.	It	n	II	lU	7.600	It	6th
25	II	II	It	117	8,600	female	7th
26	It	II	It	128	11.000	male	7th
27	II	II	It	128	8.600	n	7th
28	It	It	n 1	122	7,900	female	6th-7th

			TABLE 5 (Cont'd)			, ,„ -.
	Date of	Fishing	Current Current	Length	7/eight		Year
No.	Catch	Ground Position	Direction Speed	(Centimeter)	(Kan)	Sex	A£:e
		2^30 «N
29	11-22	15A°20«E	EKE	131	10„700	male	7th-8th
30	II	It	ft	100	A. 800	ft	5th
31	II	"	n	123	8.200	female	7th
32	II	n	n	130	11.000	male	7th
33	It	It	tt	128	10 o 000	n	7th
3A	"	II	II	122	8.000	female	7th
35	II	It	n	105	6.000	male	6th
36	II	n	It	117	8.000	female	7th
37	II	II	"	102	5.500	male	5th^6th
38	II	>i	It	120	8„500	female	7th
39	II	11	tt	123	8.500	It	7th
i^O	If	il	It	1??	10.500	male	7th
i^l	II	11	It	110	60OOO	tt	6th
iU	II	II	ti	122	10^500	ti	7th
^3	II	II	H	uu	10o500	II	7th
U	n	n	n	110	6.500	female	6th
^5	II	It	n	100	5.000	male	5th
A6	It	H	It	107	6.000	tt	6th
47	tt	tt	n	131	10.100	ft	7th-8th
IS	II	II	II	121	9.000	n	7th
iS	n	n	ft	131	11 0 000	It	7th-8th
50	n	It	n	130	10.500	tt	7th
51	II	II	It	103	A. 800	It	5th-6th
52	n	11	n	129	10c 500	It	7th
53	n	It	tt	125	9.000	female	7th
5U	II	ft	It	128	10.000	It	7th
55	n	II	II	130	9.300	II	7th
56	II	tt	ti	119	8,000	n	7th
57	II	It	It	uo	13.000	tt	8th
58	n	tt	n	119	8.800	n	7th
59	n	It	ft	121	9,000	male	7th
60	It	It	It	125	10.000	tt	7th
61	It	It	It	130	11,000	(t	7th

TABLE 6

	Dnte of	Fishing	Current	Current	Length	Weight		Year
No.	Catch	Ground Position	Direction	Speed	(Centimeter)	(Kan)	Sex	of Age
		3025'N 159027 K
1	11-29	SE	-„	125	H„000	male	7th
2	II	n	It		125	10.000	female	7th
3	II	n	It		123	10.000	male	7th
A	If		II		128	9.000	ti	7th
5	II		It		125	10 0600	It	7th
6	It		It		122	8.300	female	7th
/	II		II		121	9.000	male	7th
8	If		It		123	9,800	ft	7th

^5=

			TABLE 6 (Cont'd)
	Date of	Fishing	Current Current Length	Weight		Year
No.	Catch	Ground Position	Direction Speed	(Centimeter)	(Kan)	Sex	of Age
		3025 5 N
9	11-29	159027 "E	SE	125	8.900	female	7th
m	n	II	n	120	9.200	ft	7th
11	n	11	n	108	5.700	n	6th
1?	n	It	n	135	11.100	male	7th-8th
13	n	II	n	135	11.000	It	7th-8th
U	n	II	II	125	9.100	female	7th
15	n	II	n	125	10,000	male	7th
16	ti	II	"	122	9o4D0	n	7th
17	II	II	n	108	6.800	II	6th
18	II	n	11	110	5.900	II	6th
19	ti	n	II	129	9.000	female	7th
20	n	II	II	120	9o200	n	7th
21	u	It	It	119	9.000	It	7th
22	II	II	It	128	10. 500! male	7th

			TABI£ 7
No.	Date of Catch	Fishing Ground Position	Current Current Direction Speed	Length (Centimeter)	Weight (Kan)	Sex	Year of Age
1 2	12-3 11	5020 'N 162^059 'F. n	Unknown II	120 120	7,400 7.400	male female	6th- 7th 6th-7th

TABLE 8

	Date of	Fishing	Current Current	Length	Vfeight		Year
No.	Catch	Ground Position	Direction Speed	(Centimeter)	(Kan)	Sex	of A^
		3045 'N
1	12-6	165°40"'E	E	130	10.100	male	7th
2	n	11	n	127	9c400	female	7th
3	II	II	n	129	10,500	male	7th
4	N	It	II	12/,	8o500	female	7th
5	n	II	It	112	7.500	It	6th
6	n	It	It	122	8.500	H	7th
7	II	II	II	125	8.500	II	7th
8	n	(1	II	132	11„200	male	7th-8th
9	It	II	It	115	8,500	female	7th
10	It	It	II	105	5.500	n	5th-6th
11	11	It	It	106	5.800	male	6th
12	II	II	M	102	5.300	It	5th- 6th
13	It	II	11	108	6.100	It	6th
U	II	11	II	11»	6.200	female	6th
15	It	It	n	122	9.600	male	7th
16	II	1!	II	123	9»600	female	7th
17	II	II	II	105	7.000	male	6th
18	n	n	It	109	5c 800	female	6th 6th
19	It	n	II	108	7.000	male

-6-

			TABLE 8 (Cont	•d)
	Date of	Fishing	Current Current	Length	Weight		Tear
Noo	Catch	Ground Position	Direction Speed	(Centimeter)	(Kan)	Sex	of Age
		3045 'N
20	12-6	165°40'E	E	124	10o200	—	7th
21	n	11	If	112	4.400	female	5th»6th
22	n	II	11	122	9«500	It	7th
23	II	II	It	117	8.400	—	7th
2U	H	It	It	130	11.000	male	7th
25	II	It	11	126	8.400	f emal e	7th
26	II	11	It	113	9.000	ti	6th-7th
27	II	II	It	111	8.000	It	6th
28	11	It	II	107	4o900	It	5th-6th
29	It	II	II	127	9.300	male	7th
30	It	II	II	125	9o700	"	7th
31	n	II	It	109	5o800	female	6th
32	II	II	II	124	8.700	male	7th
33	It	It	II	127	9o300	female	7th
34	It	It	II	109	6e700	male	6th
35	It	II	II	105	6.300	It	6th
36	It	II	It	107	5.700	female	6th
37	II	It	II	120	9.400	male	7th
38	It	11	11	109	6.700	female	6th
39	It	II	It	109	6.000	It	6th
AO	II	II	It	127	11.000	male	7th
a	It	II	n	104	6o500	female	6th
42	II	tt	II	97	4o800	male	5th
43	II	II	II	120	10.000	ft	7th
44	II	11	tt	127	9o300	female	7th
45	II	II	II	118	9,000	male	7th
46	II	II	II	12?	9o700	It	7th
47	II	II	ft	127	IO06OO	ft	7th
48	II	II	It	105	5o800	II	6th
49	II	n	II	125	9.500	female	7th
50	II	II	It	117	7.700	ft	6th=7th
51	11	II	n	106	6.000	male	6th
52	II	II	ft	121	9.500	female	7th
53	II	II	It	128	11.000	male	7th
54	n	n	11	109	6c900	female	6th
55	It	n	tt	120	9.800	male	7th
56	II	II	n	106	5o500	female	5th°6th
57	It	II	II	127	10.400	male	7th
58	II	II	II	118	8,300	n	7th
59	M	II	Tt	127	9»700	female	7th
60	II	II	tt	108	8.500	male	6th»7th
61	II	II	II	117	7.700	female	6th-7th
62	II	II	II	128	11^000	male	7th
63	It	n	n	127	10.000	n	7th
64	It	It	II	130	10.500	ft	7th
65	II	n	It	130	lloOOO	It	7th
66	II	II	II	118	8.400	II	7th

-7-

The Correlation Between the Length and Weight of Yellowfin Tuna

Based on measurements taken aboard the Shonan Mam during the course of ex- perimental tuna fishing in 193^. January 1935.

I Intiroduction

This paper Is an attempt to show the correlation between the lengths and weights of iX yellowfin tuna taken during experimental tuna fishing in 193^1.

II ISethod of Measuring Length and Weight

The fish were weighed in the condition in which they were when captured and their lengths were taken as the horizontal distance between the snout and the end of the base of the caudal (see the accompanying sketch). The units of oeasurei»nt employed were kilograms and centimeters.

Ill Summary

As is clearly shown by Figure 1, the coordinates of each specimen were found by representing the weights (W) on the X axis and the lengths (L) on the Y axis. The line XY was found by the "method of great majority" CsicH. The line XY satis- fies the equation L s a^. In other words, if a number of points are taken at random on this line, a line connecting the points whose coordinates are represented by Log 10 L Log 10 W of these points taken at random can be considered to be roughly a straight line, as shown in figure 2. If we calculate the constants a and b of the equation L s aW** in Figure 2, they are as follows:

a » 40.12 b s 1/3

Accordingly we arrive at the equation

L ' m,TL2K 1/3

17 Conclusion

As shown in the preceding paragraph, the correlation between the lengths and weights of yellowfin tuna within ttie range of 5 to 60 kg taken within this area at this season can in general be shown by the formula given in Paragraph III.

[Tigure 1 is a scatter diagram of the lengths and weights with a curve fitted to it. Figure 2 is a graph with a straight line connecting points whose coordinates are the logs of weights and lengths. There is also a sketch of a tuna showing what measurement was used for L.3

2

^

■5

9.

S

MN

in

s

4 iH i-t '"^ »^

9

^ CM

B6

^^5

[©iqfSsxiT s8JTi3t/1 (l 207)

10

Growth Curves of Blue-Fin Tuna and Yellow-Fin Tuna Based on The Catohes

Synopsis [in English]

No investigation has been made on the scale and otolith of the tuna from the Seas of Japan with reference to the growth rate of the fish. In the pres- ent paper are given frequency histograms (Figs, 2 and 5) showing body-weight distribution of bluefin tuna (Thunnus orientalis Tenuninok fc Schlegel) and yel- lowfin tuna (neo thunnus macropterus Temminok & Schlegel) from Shigedera fishing ground which is situated at north-eastern corner of the Suruga Ray (Fig. 1). The data were obtnined from 1924 to 1931 inclusive, and can be divided into several age-groups as plotted in Figs. 4 and 6, in which solid circle indicates individual fluctuation of the body-weight and encircled dot shows the average body-weight of a large number of specimens which were caught there at the same time and nearly of the same weipht. The curves are free-hand smoothing. [ end of English synopsis ]

It is difficult to find out the growth of fishes which migrate widely in the ooeans, and the study of annuli and otoliths is still not very far ad- vanced. The author has used data on the weights of individual fish from the records of catches of black tuna and yellowfin tuna on the Shigedera fishing grounds in the northeastern corner of Suruga Bay (Fig. 1), and has deduced the growth rates of the fish taken on those grounds on the basis of graphs of the weight distributions.

Yoimg black tuna are first taken in the large set-nets of these fishing grounds around July and August, and thereafter some are taken every day. From the end of the year through the early part of the following year these fish aire from 2 to 4 kg in weight; in the peak season of April, May, and July they weight about 5 kg; and in the spring of their third year they a.ttain a weight of about 10 kg. During this period they are called small meji, medium meji, and large meji depending on their weight. In the spring of the third year from about March and April these second-year fish (large meji) disappear com- pletely from the catch, and the only fish taken after this time are either first-year fish or those much larger than the second-year fish. If we except these young fish and separate the large black tuna which are taken by weight groups, we get a graph of weight distribution like that shown in Fig. 2. This graph can be divided according to the differences in the weights of the fish into three groups of small, nediian, and large tuna. Although from 1924 to 1928 the average weights of the fish in the small and medium groups tended gradually to increase, it can be seen in Fig. 3, which shows the fishing season for each group, that the season for small and medium fish was coming later each year and it may be thought that the increase in the average weights was related to this lag.

Since it was already possible to ascertain clearly the rate of growth for fish under the second year of age, we were able, by considering the above- mentioned three groups of small, medium, and large fish to be respectively third-, fourth", and fifth-year fish, to draw a growth curve for the blaok tuna «LS shown in Fig. 4, However, the rate of increase in the body weight in the summer season appears to be greater than that shown for the summer season in the corresponding portion of the smoothed growth-rate curve covering a six- year period, and marked differences are notloeable in the case of the fourth- and fifth-year fish. This leads one to believe that there is a marked differ- ence between summer and winter growth. Only one or a few fish of the sixth year and older are taken each year and it is therefore not possible to find their rates of growth,

11

The catch of yellcwfln tuna, both adults and young, on these grounds is a great deal smaller than that of black tuna, and the season is limited to the Buir."<er. Excluding the young yellow mejl. the iieight distribution was sou^t for yellowfin weighing over 10 kg. The graph of this distribution is shown in Fig. 5 where it can be seen that the maximum values for the number of fish of each size in the catch are rather widely separated. If we take these as the average weights for /ellowfln of each age in the summer season and plot a growth curve, we get the result shown in Fig. 6, In the case of yellowfin over 50 kg In wei^t the maxijnum values for the number of fish in the catch are not clear, the number of fish is aoalla and accordingly their growth rate is unknown.

(at the Flsherias Experiment Station)

	Suruga ^ — ■' 4	ShigedAraX
Totomi f	> I«u
/	/ Suruga Bay	)
1 (		V

Fig.l Location of the Shig«d«r« fishing grounds

12

6o 7o fco *o 40 30 to \o

o

to

o

|o

o

lo

o

&e

^o

3e

Zo

\o

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Kl ^Jk VTv\3e,r- oV cqVcV>

ktnaW

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ru

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_Bo<i^^^l^e■,oV^i

Flg.2 Distribution of .relghts of black tuna In th© catch (young fish

omitted)

Nu<r\\oer oV' caVcV\

~i i -i^

+

J_:-:~^,--V I, .-1 r. .:

To , 3o AC So

t— rt — " —

rri:v.-.'.rL'~:i-.^:.U

Bociv^W^-tc^ViV

Fig. 5 Koight distribution of yellowfin tuna in the catch (young

fish omitted)

13

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o m 1 .

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14

!CE

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140. 130.

G> R_ O w T H C. 0 1^ V G: OF^

hv^nov.\c> or » €;-n Vdl \ 3 )

Month

HI la^^K.iiiQ'^'Oisc tm^ ©uoiisL^^ffiaL^^dG-fi

Fig.;4. Growth curve for black tuna

Fish oi"" the year to fifth-year fish (sixth year after hatching)

Summer grovrth curve

0 Average vreight of a large number of black tuna of roughly the

same sxze taken at the same time

o Vfeight of individual fish

15

kg

60

50

UO

30

20

10

Body weighi
	/' r> ^~^ \ A / "T" \ \ i-'^ 1	1 r^ ■ . J		-' 'P
-	..				k- //	'/ n
				c^<;/
,					y^"
				•\.^	T
				0<^ ...
		«		^
1
!	%^	^
1 \ i ■ ^	^i
t	f ^^^-^	..-.J. . .•.,!. -U .-J.

0 Grour> I Group II Group III Group IV Group V Group VI Group

Fig. 6 Growth curve for yellowfin tuna

0 average weight of a large number of fish

of roughly equal weight taken at one time

o weights of single fish

16

On the Age of Yellowfin Tuna trom Palau Watera

by Kenzo Ikebe, Technician

[from South Sea Fishery News, Vol.3, No, 10. December 15, 1939]

Data on the lengths and weights of fish are of great value as reference materials for the study of the grounds where the fish were taken. For this rea- son the author took measurements of 11 yellowfin tuna taken on the long lines of the Hakuo ITaru November U west of Palau (position of fishing grounds, 7® 10' N, 134° 3' E).

The following table shows the results of measurements of the body length, total length, body depth, body width, and weight as well as the condition factor

-2 X 1,000) calculated according to the method published by Mr. Kinosuke

l3 Kimura of the Central Fisheries Experiment Station.

(

			Table 1
						Condition
No.	Total Length	Body Length	Body Depth	Body =«.dth	Weight	Factor
	cm	<aL	sn.	fiSL	1S&
1	158	133	34	27	49.1	20-9
2	138	lU	27	23	31.8	21.5
3	Ul	116	31	25	37.0	23.7
4	Ul	117	31	26	38.6	24.1
5	U9	123	33	25	42.3	22,7
6	Ul	118	31	23	37.2	22,6
7	133	113	25	22	31.4	21,8
8	U5	125	30	23	43,0	22-0
9	152	129	30	25	48,7	22.7
10	U2	121	31	25	38.8	21,9
11	135	114	29	24	34.1	23.0

The author then calculated the condition factors for two sets of data which had been collected aboard the Hakuo Maru before he reported for duty at this Station. These data are segregated b7 sexes and one set waa taken from 11 yel- lowfin caught east of Palau on May 11 of this year (position of fishing ground, 7° 18« N, 134° 42' E) while the other set represents 14 yellowfin taken May 14 at 7° 21" N, 134° 44' E„ These data are given in the following tables.

According to a study by Dr. Hiroakl Aikawa entitled "The Age of Fishes and Changes in Their Length and Weight" which was published in Volume 4, Number 11, of Marine Fisheries CKaiyo Gyogyo], it is possible to find the age of « j^Jf^ ^ comparing its wei^t and length with the figures supplied in a table. (This study originated in the relationship between the length and weight and the verte- bral bones of fishes, and was published in Volume 7, Number 2, of the Bi^ll?^ii^ of the Jafyaneae Society of Scientific Fisheries.)

The author was greatly impressed and interested when he learned of the ex- istence of such an extremely valuable thing as a ready reference table on the age of fish, and decided to try to compare the results of these three sets of

17

Table 2

No.	Sex	Total Length	Body Length	Body Depth	Body Width	Weight	C.P.	Gonads
		cm	S&	SO.	SSL.	U
1 2	M M	1?^ uo	128 120	31 29	2U 23	39.5 31.5	18.8 18.2	rather ripe n
3	)f	1/42	123	29	23	34,0	18,3	»
U	F	148	126	30	24	36.5	18.2	n
5	M	1^8	127	33	25	40.9	20,2	n
6	F	U5	123	30	zu	^U.^	18.7	R
7	M	U6	121	31	23	37.0	20,9	n
8	M	163	135	35	26	47.8	19.4	n
9	M	123	10-4	25	19	19.0	16.9	n
10	M	U8	125	32	2U	38.0	19.5	n
11	M	U5	120	29	2U	33,7	19.5	n

Table 3

Ho.	Sex	Total Length	Body Length	Body Depth	Body Width	Wslght	C,F.	Gonads
		fiA	SB.	SSL	Qg	"S"" ■
1 2	F M	U7 152	122 129	28 33	23 25	33,5 42,0	18.4 19.6	rather ripe
3	M	156	129	32	25	41,0	19.1	«
4	F	U5	122	29	22	33,0	18.2	n
5	M	U4	12?	31	22	34,5	19»0	R
6	U	U5	120	30	23	36.0	20,8	It
7	P	135	118	29	22	30.0	18.3	ft
8	M	150	125	31	23	39.0	20.0	H
9	M	U5	121	31	24	37.0	20.9	n
10	F	U3	122	28	23	31.0	17.1	«
11 12	II F	155 155	127 127	31 31	24 25	42.5 38.0	27.5 18.6	n n
13	F	102	87	21	16	10,5	15.9	n
U	M	138	118	30	22	32.0	19.5	n

16

measurements of Palau yellowfin with the table in order to determine the ages of the fish. The following tables show the age related to length and weight.

Species — yellowfin tuna

Age	z	Length	ffel^ht
	' ■ " " shaicu	kap
First year		under 1.2	under 0o4
Second year		1.2 " 1.8	0.4 - 1.2
Third year		1.8 - 2.3	1.2 - 2,4
Fourth year	2.3 - 2,8	2.4 - 4.1
Fifth year	2.8 - 3,3	4.1 - 6,0
Sixth year	3.3 - 3.8	6,0 - 8,0
Seventh year		3.8 - A,3	8,0 -12.0
Eighth year		Ao3 - l,B	12,0 -16.0
Ninth year		over ii,8	1 over 16,0
TN. 1 shaku «	.99^ foot
1 kan = 8.	27	pounds

Converting shaku and kan to centimeters and kilograms, Species — yello*-fin tuna

Age	Length	Weight
	cm	Kfi.
First year	under 36,4	under 1.5
Second year	36.4 - 54.5	1.5 - 4.5
Third year	54.5 - 69.7	4.5 - 9.0
Fourth year	69.7 - 84.8	9.0 -15.4
Fifth year	84,8 -100.0	15.4 -22.5
Sixth year	100,0 -115.2	22.5 -30.0
Seventh year	115.2 -130.3	30.0 -45.0
El^th year	130,3 -U5.5	45.0 -60.0
Ninth year	over 145.5	over 60.0

Row if we compare the fish listed In Table 1 with these figures, Ho.l Is in its eighth year, No. 2 corresponds to the sixth year in length but to the seventh in weight, No. 3 to Noo 6 are all in their seventh year. No. 7 is in its sixth year by length and in its seventh year by wei^t. No. 8 is a seventh-year fish, Kg. 9 is seventh-year in length and eighth-year in weight. No. 10 is a seventh-year fish, and Nodi is within the sixth-year length range and the seventh-year wiight range. The following figures show in abbreviated form the age determina- tions for the fish listed in Tables 1, 2, and 3.

in Table 1 sixth or seventh year 3 f iflh

seventh year.. 6 fish

seventh or ei^th year 1 fish

eighth year, 1 fish

total 11 fish

19

in Table 2 fifth or sixth year 1 fish

seventh yearo 9 fish

eighth year. 1 fish

total 11 fish

in Table 3 fourth or fifth year 1 fish

seventh year 13 f isth

total U fish

Combining all of these data «a find that of a total of 36 fish

seventh year.,., 23 fish

sixth or seventh year 3 fish

eighth year, c, 2 fish

fourth or fifth year 1 fish

fifth or sixth year 1 fish

seventh or eighth year. ....... 1 fish

From a consideration of these data we can conclude that among the yellowfin tuna taken on long lines in Palau waters recently fish in their seventh year predominate with some admixture of both older and younger year classes.

It is the author's intention to obtain as much accurate data as possibl** hereafter and to use these data to investigate the ages of skipjack and albacore ac well as yellowfin tuna not only in Palau waters but everywhere in the archi- pelago. (December 1)

Measurements and Ages of Tuna from Palau Waters

by Kenzo Ikebe, Technician

[from South Sea Fishery News fNanyo Suisan Joho], Vol.4, No.l, February 5, 19il0]

In the preceding number of this journal the author published a paper on the ages of yellowfin tuna ftrom Palau waters. In presenting a second paper on this subject there is some danger of repetition, but since it is thought that in at- tempting to determine the age of firti by measuring their length and woight the more data the study is based on the more accurate and reliable will be the re- sults, the author has decided to attempt to write something more on the subject.

Last December on the second cruise of the Nanko Fishing Company's Awa Maru (92 tons, 185 horsepower) after her arrival ftrom Japan she operated on the fish- ing grounds within a radius of 100 miles to the southeast of Palau. On December 23 a big catch was made at a point ^iO miles southeast by south of the Palau lighthouse. Length and weight were determined on 10 spearfish fniakaira m^tsukurilil. 35 ble-eyed tuna fParathunnus mabachi] , and 51 yellowfin tuna fNeothunnus macrop- tfiUlgJfrom this catch. These data are given below.

These measurements were taken lAen the catch was being weighed while the fiah were being transferred ftrom the Awa Maru to the ftreighter Ebon Maru. In

20

order not to interfere with the work It was necessary to do the measuring aa rapidly as possible and so only the body lengths and weights were tsken, the total length, body depth, and body width being omitted.

Body length was measured from the snout to the caudal peduncle, and the weights wore taken after the fish had been completely eviscerated„

Table 1 ftekaira mitsukurii

* "■"■ ■' ' " '	Body Length	Weight
	shaku	jcfia
No. 1	5.7	12.8
2	6.1	13.7
3	5.7	13.5
U	6.0	15.9
5	6.5	11.3
6	5.7	12.0
7	5.4	10,5
8	5.6	12.0
9	6.0	13.5
10	5.5	10.8

TN. 1 ahaku - .994. foot 1 ^aa = ®»27 pounds

Table 2 Parathunnus mebachi

'	Body Length	Weight		Body Length	Weight
	ahtiku	kan		^lakj^	kan
No. 1	4.5	U.5 18,1	No. 19	4.0	10o3
2	4.9	20	4.5	12,7
3	4.4	13.5	21	4.2	12.3
U	5.3	22.5	22	4.1	10.0
5	4.6	17.0	23	4.1	lie 5
6	4.9	19.6	24	4.1	12.0
7	4.3	U.5	25	4.8	17,7
8	4.1	10.8	26	4.6	11.3
9	4.4	13.5	27	4.0	10.2
10	4.6	15.8	28	3.8	10.3
11	4.5	16.2	29	4.3	U,3
12	3.8	11.0	30	4.0	10.2
13	4.8	17.7	31	4.0	10.6
U	3,7	8,5	32	4.2	13.0
15	4.1	9.6	33	5.0	20.1
16	4.3	13.5	34	4.3	13.0
17	4.4	13,5	35	4.2	12.1
18	3.7	9.0

21

Table 3 Neothunnue macropterus

	Body Length	Ifelght P	Body Length	Weight
	snalFV	Issn		S^lRJ	Kaa
Ho. 1	4.0	9»5	No. 27	4.0	8.4
2	4.1	9.6	28	4.0	8.8
3	4.5	13.0	29	4.1	10.0
U	4.2	9.5	30	3.9	8.1
5	4.1	10,5	31	3.9	8.5
6	4.2	11.0	32	4.2	11.6
7	4.0	10,5	33	3.8	7.5
8	4.2	10,5	34	4.2	10.6
9	3,7	8.4	35	4.2	10,6
ID	4.1	10.7	36	4.0	9.6
U	3o8	9,0	37	4«4	12.5
12	4o2	10.0	38	3.8	8.1
13	4.1	11.0	39	3,7	7.7
U	3,9	8.5	40	4.0	9,3
15	4.0	8,8	a	4.1	9.4
16	4.0	9.5	42	4.1	9,6
17	4,3	11,6	43	3,7	8,0
18	4.3	9.1	44	4,3	11,5
19	4.0	9.2	45	4.5	11.9
20	4.2	11.0	46	3c 9	8.5
21	4.2	9.4	47	4.0	10.2
22	4.1	9.3	48	4.1	9.7
23	4.0	8,0	49	4.3	12.1
2U	3.7	6.0	50	4.2	11.2
25	3c7	9.0	51	4.2	10,0
26	4.1	10.7

Unfortunately Tables 1 and 2 can only show the slaes of the fish because no study has been published as yet on a ready reference table of the ages of spearflrfi and big-eyed tuna, A comparison of the yellowfin tuna data in Table 3 with the age-class table using the same method as reported in the preceding number of this jorimal gives the following results:

total 51 fish seventh year 41 fieh

eighth year 4 fish

sixtb year 4 fish

sixth or seventh year...... 2 fish

It is thought that these figures have further confirmed the fact that the majority of the yellewfin tuna taken on long lines in Palau waters are fish in their seventh year. (Since the table of age-classes was jwblished in the pre- ceding number it has been omitted here.)

22

Meaauraments of Yollowfin Tuna from South of the fferslialls

by Kenzo Ikebe, Technician

[from South Sea Fiehory News QJanyo Suiaan JohoJ, Vol»A, No, 2.]

Iterch 5, 19/^0

Prom March to June of 1939 the South Seas Colonization Company's boat, the Ebon Maru (195 tons, 320 HP), with the Company's Technician Haruo Watanabe and Assistant Technician Seilchi Shimada aboard, carried out experimental tuna long- lining in waters south of the Mnrahalls. The following is the result of an at- tempt to determine the ages of the yellowfin tuna reported in the catch data from that cruise c

Table 1

Date -» May 8 Position of fishing ground — 6° OS'S, 16^° 26'E

No,	Body Length	Weight
	meters	kan
1	1.20	9.10
2	1.20	9.10
3	1,20	9.60
U	1,10	9.^0
5	1.10	6,60
6	1.^0	11.60
7	1,30	10.40
6	1.30	10o20
9	1.20	7.80
10	1,20	8.60
11	1,20	8,60
12	1.15	7.90

TN. 1 kan s 8,27 pounds

Table 2

Date ~ May 10 Position of fishing ground — 9° 00 'S, 163° 30 'E

23

Table 3 Date »- Ftey 11 Position of fishing ground -- 7° 01 'S, 165° 15 'E

No»	Body Length	BbiKht	aHBSsaartt
	JSaiiSIA	kan
1	1.20	8,60
2	1.20	8.10
3	1,20	9.10
k	1.25	9c 60
5	1.20	9ol0
6	1.20	7,70
7	1,-W)	12.60
8	1.20	8.30
9	1.30	10.00
10	1,. 30	11,10
11	lc30	8,60
12	1.30	8.15
13	1.20	6.60

Date — May H

Table U Position of fishing ground ~ 6* 0«5'S, 165° 55 'E

Table 5 Date — May 13 Position — 3° ^8'S, 166° 28 'E

No,	Body Length	WsiKht
	in^tyra	Kaa
1 2	1.20 1,20	9.00 8.10

24

Table 6

	Date — May lU Positi	on — 1° 03'S, 170° 21'E No. Body Length
No.	Body Length | Vfeight	Tleight
	metiK^^j} i kan		idiptere	kan
1	1.20	8.10	16	1.23	9.10
2	1..20	9,10	17	1.23	8.60
3	1„20	7.60	18	1.23	8.70
A	1.20	9,10	19	1,20	9.00
5	1,20	9o80	20	lo20	9o-i0
6	1,20	8«60	21	1,10	8.80
7	1,20	3,60	22	lol5	8.10
8	1.20	S.IO	23	1.30	9.60
9	1,15	6,40	2A	1.20	9»30
10	1,20	8.80	25	1.20	8.20
11	1.20	8.90	26	lo20	7.60
12	1.20	8.10	27	1.20	8,30
13	1.20	9.10	28	lo20	9.30
U	1,20	8,60	29	1.25	8.7D
15	lo20	8.60

Date — May 16

Table 7 Position — 1° 20 'K, 172° 30''E

Body Length

1,20 1-20 1,-20 1„20 1,20

Vfeight

8.60 9c 60 8.90 7,60 8,^0

6

7 8 9

10

Body length

meters

lc30 1,20 1.20 1,30 1,20

Vfeight kan

A comparison of these figtires in order beginning with Table 1 with the ege- clasB table used in the preceding number of this journal gives the following results:

in Table 1 sixth year. 2 fish

sixth or seventh year. ...<,,....» 2 f iah

seventh year. . , 7 fish

seventh or eighth year... 1 fiah

in Table 2 seventh year ,,....,. A fish

in Table 3 sixth or seventh year 2 fish

seventh year, . . , 10 fish

eighth year. 1 fiah

total 12 fish

total U fish total 13 fiah

25

In Table K sixth or sarenth yaar 1 fish

seventh year U fish **'**•'- ^ fish

In '^iblo 5 seventh year ..„ , 2 fish total 2 fish

in Table 6 sixth year ».,... 1 fish

sixth or seventh year 4. fish total 29 fish

seventh year. «.«...« 2A fish

in Table 7 sixth or seventh year 2 fish

seventh year 8 fish total 10 fish

If the above data are combined no get a total of 75 divided as follows:

sixth year , , . . o . 3 fish

sixth or seventh year ...,,11 fish

seventh year, , . . . , , . , . , 59 fish

seventh or eighth year, , . « . . . , , . 1 fish e' ghth year. , „ 4 1 fish

According to this the majority of the yellowfin taken on long lines in the waters south of the Marshall s are fish in their seventh year with only a small admixture of fish of older and younger year classes.

A conparison of the yellowfin tuna inhabiting Palau waters and those vAich occur south of the Waraballs shows that as far as body measurements are concerned they are almost identical, and it is therefore not difficult to deduce that they belong to the same stock of migratory fish. (February 7)

On the Bfeaauremonts of Albacore and Yellowfin Tuna from Saipan Waters

by Kenzo Ike be, Technician

[from South Sea Fishery News £Nanyo Suiaan JBho], Vol,^, No. 5. July 30, 1940 ]

In May of this year a survey was made aboard the research vessel Zuiho Maru of the albacore fishery around the northern outlying islands of Saipan. The general results of the investigation have been reported elsewhere so I have decided to import in this journal only on those phases having to do with the size and age of albacore and yellowfin tuna, basing my remarks on the data col- lected during the course of the survey.

This survey was conducted during the period from May 5 to May 28. The iarea covered was the waters around the outlying islands north of Saipan betwi U4 45 • and U6° 25" east longitude and 18*^ 11' and 21° 55' north latitude.

During the course of these investigations a total of 8 albacore and 58 yel- lowfin were taken (all on long lines). The following table shows the lengths and weights of these fish, the ages deduced from these measurements, and the dates and positions of capture.

It should be noted that the weights are those of eviscerated fish.

26

Iftble 1 Albacore fThunnus :if.rr;o_]

Ko.	Date	Position	Body Length Vteight	Age ...
			_cm^	kan
1	5-5	18022 'N,U5°13'E	102	6.70		9
2	n	ft B	102	6.00		8-9
3	n	« H	95	4.80		n
U	5-22	19°50'N,U5°02'E	110	7.50		9
5	II	n n	102	5.70		8-9
6	5-27	20°07'N,U5°U'E	105	6.70		9
7	5-28	19*04 'N,U5%8»E n n	99	4.80		8-9
8	n	102	5.60		«-9

The age deterralnationo In the table arc, as in the preceding papers of thio aeries, based on the article by Dr. Aikswa entitled "The Age of Fishes and Changes in Their Length and Wei^t" (see i^la^ Fisheries C^siiyo Gyogyo], Volume 4, Number 11). Of the 8 albacore 3 fall in the ninth-year class and 5 can be considered to be either eighth- or ninth-year fish. In the case of alba- core those within the ranges of 4.80 - 6.40 }caa in weight and 85 - 94 cm in length are considered to be in their eighth year, and those over 6,40 kan in weight and 94 cm in length are regarded as being in their ninth year. Judging from the fact that the oldest albacore are ninth-year fiah, we can see that the albacore which migrate Into Saipan waters, although they are very scarce numerically, belong almost entirely to the largest and oldest part of the stock.

Table 2 Yollowfin tuna PNeothunnus macropterusl

No,

Date

1	5=21
2	5»22
3	5-24
U	n
5	II
6	11
7	If
8	5-25
9	n
10	n
u	M
12	It
13	n
U	II
15	n
16	If
17	n
18	5-26
19	n
20	H
21	5-27
22	n
23	n
24	1?
25	n

ail 1' III i*n«itf;qriiii inum—

Position

18°1I'N, 19°50'N, 21^55 'H,

145°15"E 145^02 'E 145°01'E

21^15 'N,

n n n n n n

20O20'N, n

20O07'N, n

It

It

It

146°25'E It

n II II It n II n II

146°20'E

n n

U5«'14'E

n II It n

ly Length	i-fc~fa^t.ugai 1 11 ill r 7«ight	Agj3
m	kan
117	12.00	7-8
112	8.60	6-7
103	10.50	6-7
125	9.00	7
122	8.50	7
125	10.50	7
117	8.50	7
125	9.10	7
122	8.90	7
134	11.50	7-8
116	8.60	7
123	8.60	7
123	3.50	7
125	9.50	7
128	10.00	7
120	8,30	7
128	9.30	7
125	9o50	7
128	12,50	7-8
132	11.50	7-8
129	9.00	7
lU	7.00	6
130	11.20	7
115	7,00	6
115	8.00	6

27

]rable 2	coQtinuedJ
No.	Date	PosHvion	Body Length	Weight	Age
			cp,	kan
26	5-27	20°07'N,H5°U'S	116	8,00	7
27	n	n n	123	12o50	7-8
28	5=28	19*^04 'M,U5°48'E	55	0.89	2-3
29	It	tt n	56	0.95	2-3
30	n	n It	59	1.02	2-3
31	n	11 n	51	0.73	2
32	n	•t B	105	5.10	5-6
33	n	It It	111	6.00	6
31	n	n tt	103	5.00	5-6
35	n	n It	lOA	6.10	6
36	It	n n	115	6.50	6
37	n	n n	100	4.80	5
38	ti	n tt	95	3.10	4-5
39	n	n rt	80	2.40	4
^	n	•» It	90	3.80	5
a	II	t» If	95	4.10	5
iW	tt	tt It	105	5.60	5-6
O	H	n tt	110	6.20	6
a	n	tl u	106	5.70	6
A5	It	It It	100	9.30	6-7
^6	n	n It	105	5,60	5-6
47	(1	n It	100	5.00	5
48	It	tt n	104	5.60	5-6
/♦9	n	It tl	91	3.90	5
50	It	It n	102	5.50	5-6
51	n	tl II	106	6.00	6
52	n	It If	102	6,00	6
53	n	tl n	108	5.70	6
54	n	It n	107	5.00	5-6
55	n	n It	123	9.10	7
56	n	n n	97	4.40	5
57	ti	11 ft	98	3.60	4-5
58	n	II tt	69	1.70	3

(Note) The four fish tram No. 28 to Mo, 31 were weighed vdthout being gutted be- cause of their small size.

When W8 examine separately the fish taken from May 21 to May 27 and those taken on May 28, we find that the 27 fish in the former group fall into the fol- lowing age claeseet

seventh or ei^th year 5 fish

sixth or seventh year 2 fish

seventh year 17 fish

sixth year 3 fish

Thus these fish resemble those taken at Palau and south of the Marshalls (described by the author in three previous articles in this journal) in that seventh-year fish are in the majority with an admixture of a few fish from the adjacent older and younger year-classes.

28

Of the 31 fish in tha latter gri^up the number in each age class is an fol- lows:

seventh year. 1 f ieh

sixth or oeTenth yeer <>.........<,....<> 1 fish

sixth year. . , „ , ....<. 8 fish

fifth or sixth year c . . ^ . . . , 6 fish

fifth year, ,7 fish

fourth or fifth -rear. . . „ „ c, . . ,. . 2 fish

fourth year. « 1 fish

second or third year , 3 fish

third year. , . . 1 fish

second year «. 1 fish

In this group the seventh-year fish are outnumbered by the sixth-year and fifth-year fish, and there is an admixture of young fish of the fifth, fourth, third, and second y«ar-clai3ses which Tiakes this sample differ greatly in age com- position from any yellowfin tune Trtiich I have examined hitherto. Of particular interest is the seccnd-ybar fish 51 cn» in length and 730 moTg.Tie in weight which was the smallest yellowfin taken in the oourae of the survey. The presence of such a young fish makes one think that the spawning grounds of the yellowfin tuna cannot be far from this area,

* « *

Dr, Aikawa'a table of the ago of fishes correlated with length and vraight ranges

1. Albacore

Weight

Age

Fish of the year (0 age group) Second-year fish (I age group) Third-year fish (II age Fourth-year fish (III age Fifth-year fish (IV age group) j 53 - 67 Sixth-year fish (V age group) Seventh-year fish (VI age group) Eighth-year fish (VII age group) Ninth-year fish (VIII age group)

Length

0o/V9 kg I 0.13 kan ia3 - 1=39 0,3 - 0.37 1.39 - 3,19 0.37 '0.8? 3.19 - 5.63 5«63 - 8,62 8o62 -12.38 12.38 -18,00 18.00 -Z^.OO 2/^.00

29

2. Tellowfin Tuna

Age

Fiah of the year (O age group) Second-year fish (I age group) Third-year fish (II age group) Fourth-year fish (III age group) Fifth-year fish (IV age group) Sixth-year fish (V age group) Seventh-year fish (VI age group) Eighth-year fish (VII age group) Ninth-year fish (VIII age group)

Length

Weight

38 cm

38- 5U

5U' 70

70- 85

85-100

100-U5

115-130

130-U5

U5-160

1.25 ehalcu 1.25-1.78 1.78-2.30 2,30-2,80 2.80-3,30 3.3 -3.8 3.8 -4.3 4o3 <,^ A. 8 -5,3

1,50 kg

1.50» 4,3

4.3 - 8.6

8,6 -U.O

U.O -21,4

21.4 -30.0 30,0 -U.O 44,0 -57.5

57.5 -75.0

0.40 km 0.40- 1.15 1.15- 2.30 2.30- 3.70 3.7 - 5.7 5.7 - 8.0 8,0 -11.7 11,7 -15.3 15.3 -20.

(July 4)

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