DEVELOPMENT AND CONSERVATION OF TUNA FISHERIES 153 



ment and the State of California, so development of an offshore fishery 

 in this area may not be far distant. 



Blue fin 



These are tunas of temperate waters, occurring in both the northern 

 and southern hemispheres. Commercial fisheries are conducted for them 

 off California, Japan and southern Australia (Sydney to Tasmania). 

 The bluefin tunas of these three regions are probably distinct species 

 (Thun7ius orientalis of Japanese waters, T. thynniis in the Eastern 

 Pacific, and T. maccoyi in the Australian area), according to morpho- 

 logical data of Godsil and Holmberg (1950), although some taxono- 

 mists, for example Fraser-Brunner (1950), place them all in a single 

 cosmopolitan species. In any event, it seems quite certain that the three 

 groups being fished in the Pacific are quite distinct from one another. 



The bluefin of California waters is taken commercially only by 

 purse seines. The fishery is normally confined to the summer months, 

 June to September, with best fishing in July and August when the 

 schools of fish appear near the surface in waters not far from shore. 

 The supply is erratic from year to year, and average total production 

 is small, and highly variable, between 3 million and 22 million pounds 

 in various years of the past decade. 



The Japanese fishery for bluefin tuna is also pursued mainly in 

 oceanic waters within a hundred miles or so of land, by means of nets^ 

 traps, and long-lines. A considerable catch is made with nets and traps 

 close to the shore in certain regions. Some bluefin are, however, taken 

 by long-lines, incidental to fishing for other species, on the high seas 

 many hundreds of miles from land. Available statistics on bluefin tuna 

 landings in Japan indicate that there, also, the production is erratic, 

 varying irregularly between 2 million and 52 million pounds in various 

 years from 1936 to 1951. 



The Australian representative of the bluefin tuna, unlike that of 

 the California fishery, bites readily on both trolled lures and live bait. 

 According to Serventy (1941) these are small, immature fish ranging 

 from 6 to 35 pounds in weight. The fishery is conducted by small ves- 

 sels during the summer months in inshore waters, Presumably the 

 larger, adult fish occur elsewhere. Until 1951, fishing was done by trol- 

 ling only. In that year a live-bait vessel conducted fishing trials with 

 some success, and in 1952 and 1953 a small fishery has been prosecuted 

 using the live-bait, pole and line technique. 



It appears that the Australian fishery, which now produces only a 

 few hundred tons per year, is capable of considerable expansion. 

 Prospects for increased production in other areas are not possible to 



