Uno^^' investigated the covnposition of the tuna catch taken by pole fish- 

 ing in the waters east of Cape Kojima and found that in f&iy and June of 1935 

 the catch was 6« fourth-year fish, 86% fifth-year fish, and ffi& sixth-year fish 

 while in June of 1936 it was 16)5 fourth-year fish, 70% fifth-year fish, and 

 Li./& sixth-year fish. Jilhen the weight groups of the albacore taken east of Cape 

 Nojima from January to Way, 1936, and the length groups of those taken on the 

 same grounds in the same period of 1937 by the Pumi MaruU) are converted into 

 age groups by the method of Aikaiva and Kat5 '^), fifth-year fish are most 

 numerous followed by fourth-year, third-year, and sixth-year fish in that order 

 (Table 1). A consideration of that part of the reports of investigations of 

 the Fisheries Experiment Station^?) in irtiich the catch is indicated by sizes 

 of fish shows that the proportion of large fish is greater in the Northeastern 

 Area than on the distant offshore grounds (Table 2). The proportion of small 

 fish was greater on both grounds in 1937 than it vsas in 1936, however, it is 

 thought that there still appears to be room for the development of fishing 

 grounds for large fish in the distant offshore areas. 



Where two or nore of the size categories of small, medium, and large are 

 combined in the table of albe«ore catch by sizee compiled by the Japanese Tuna 

 Cannei'S Association, (6) they have been broken down and distributed proportionally 

 by numbers of fish into small, medium, and large size groups (Table 3). If we 

 compute the survival rate* from these data, me get ,5^ for 1934-, «8^ for 1935, 

 .56 for 1936, and <,6A for 1937, an average for the four years of .66. The con- 

 siderable variation in the survival rate value from year to -ypar is probably 

 due to the fact that the age composition of the fish which migrate into the 

 present limited fishing grounda cannot be regarded as the agR composition of 

 the stock. This Indicates that the above-mentioned irregularities which h^ave 

 recently appeared in the fishing situation cannot, be said to be necessarily due 

 exclusively to overfishing. This is all the more apparent when we consider that 

 the survival rate is proportionately large and that accordingly the fishing 

 rate is proportionately small. '^ 



[hotesj 



(l)Bureau of Commarcial Fisheries: The commercial fish catch of California for 

 the year 1935, Fish Bjlletin (A9) f 1937. 



(2)Hasegawa, K. s On the Report of the Sumnier Albacore Investigation. Collected 

 Lectures on the Canning of '^Jnas in Oil. February 1938. 



(3)uno, Michioj The Composition of the Catch of Tuna Taken by Pole Fishing in 



the Haters East of Caps Mojima. (Preliminary Report No.l)« Bull. Jap. Soc. 



Sci. Fish. Vol. 4., No. 5. January 1936j (Preliminary Report No. II), Vol.5, 

 No, A, November 1936, 



(A)Aikawa, Hiroaki and I&suo Kato: Age Determination of Fishes (Preliminary Re- 

 port No,l)« Bull. Jap. Soc. Sci. Fish. 7ol.7, No. 2. July 1938, 



(5) Part published in Reports of Oceanographical Investigations (58) -(61), (63), 



(6)japan Tuna Canners Association: Report of Activities for 1937 (Sixth Yearly 

 Report). 1938. 



11 



