r15 



O NUMBER OF FISH/10'' 

 ■ METRIC TONS/10* 



F ^ «■ P 



1955 



Figure 33. Annual catches of Japanese longline fisheries in the Atlantic Ocean for 

 large and medium size bluefin tuna in tens of thousands of fish and in thousands 

 of tons. 



extended northward to 1 6°N, almost 

 joining the mid-ocean one men- 

 tioned above. 



Considerable size data are avail- 

 able from exploratory fishing and 

 commercial catches in the western 

 North Atlantic These records indi- 

 cate that most of the bluefin taken in 

 oceanic waters south of 35°N and 

 west of70°W (catches north of 35°N 

 and west of 40°W have been dis- 

 cussed in a previous section) were 

 giants. 



Unfortunately, little size data 

 are available for the much more ex- 

 tensive Japanese catches. Hayasi et 

 al. (1970) reported that the Japa- 

 nese longline fishery took "small" 

 bluefin off Flonda (25°-35°N, 70°- 

 80°W), but no size data have been 

 provided. Hayasi and Shingu (1972) 

 and P. C. Wilson (personal commu- 

 nicafion) provided lengths for about 

 220 Atlantic bluefin caught in oce- 

 anic waters Most of these were gi- 

 ants, but a considerable number were 

 medium sized, although mostly of 

 the larger sizes (ages 7 and 8) oc- 

 curring in that group. It appears that 

 nearly all of the bluefin over one 

 year old taken in the westernmost 



part of the North Atlantic south of 

 35°N, and in the Gulf of Mexico and 

 the Caribbean Sea, were giants, but 

 that there have been considerable 

 numbers of medium sized, as well as 

 giant, bluefin in mid ocean catches in 

 the 1960s (Shingu et al. 1975). 



After the decline of their Atlan- 

 tic bluefin tuna catches in the late 

 1960s and early 1970s, the Japanese 

 shifted much of their effort to the 

 eastern Atlantic and the Mediterra- 

 nean. The remaining effort in the 

 western Atlantic was concentrated in 

 the northern Gulf of Mexico in May 

 and June, when giant bluefin spawn 

 there, and in the area south of the 

 Grand Banks through much of the 

 year (Shingu et al. 1975). 



The move into the eastern At- 

 lantic brought new pressure on stocks 

 of larger fish which had previously 

 been fished mainly by the declining 

 trap and seine fisheries, and on me- 

 dium sized fish which had been pre- 

 viously fished mainly by the Spanish 

 and French bait boats in the Bay of 

 Biscay. The fishery also provided in- 

 dications of a previously suspected 

 wintering ground around the Canary 

 Islands (Aloncle 1964) for the large 



bluefin which were fished in Euro- 

 pean waters in the waim season. 



The effect of these shifts in ef- 

 fort was to restore the catches to 

 levels approaching those of the mid 

 1960s. Whether they will follow the 

 pattern of rapid rise and rapid de- 

 cline illustrated for other areas by 

 the combination of Figures 34 and 

 35 remains to be seen. 



Shingu and Hisada (1976) 

 showed the length compositions of 

 samples from longline catches taken 

 in waters west of Gibraltar in May- 

 August 1973 and Apnl-June 1975. 

 The former was dominated by large 

 fish 1 90-240 cm long with a mode 

 at 205-215 cm, but also included a 

 significant number of medium sized 

 fish 135-155 cm long. Larger fish, 

 185-300 cm long with a broad mode 

 at 225-255 cm, were even more pre- 

 ponderant in the latter sample, with 

 only a scattering offish 1 10-175 cm 

 long. 



4. Eastern Atlantic Islands 



Bluefin tuna occur in the vicin- 

 ity of the Azores, Madeira, and the 

 Canary Islands (Figure 36), but 

 there has been little information on 

 the fisheries and the sizes of fish 

 until recently. 



a. Azores 



Ferreira (1932) reported on the 

 tuna fisheries of the Azores for the 

 years 1924-31. The principal catch 

 was bigeye tuna, " Paratlmnnus 

 obesiis", with bluefin tuna being 

 much less frequent. 



Seven of 219 tunas caught in 

 1930 and 5 of 1404 caught in 1931 

 were bluefin. The fishing seasons 

 usually extended from mid-April or 

 early May until July or August. 

 Ferreira docs not state the sizes of 

 fish taken, but mentions that very 

 small (50 cm) tunas occurred, as 

 well as adults. Figure 5 in his work, 

 which is described as a young 

 ''Parathitmnis obesus" of 51 cm, 

 shows, in our opinion, a young blue- 

 fin tuna. 



During cruise 63-4 of the Bu- 

 reau of Commercial Fisheries M/V 

 "Delaware", six giant bluefin were 

 taken by longline off the Azorean 

 Island of Santa Maria in May 1963, 

 and another was lost alongside the 



34 



