324 



FISHERY BULLETIN OF THE FISH AND WILDLIFE SERVICE 



Figure 1. — Oceanic region of the northwestern Atlantic covered in M/V Delaware tuna explorations, 1957-60. 



THE STATUS OF TUNA KNOWLEDGE, 1957 



A review of the literature indicated that no 

 knowledge was available of extensive tuna stocks 

 in the oceanic region of the northwestern Atlan- 

 tic and that records of tuna captures in this region 

 were relatively few. The review showed further 

 that whereas knowledge of tuna stocks of the Con- 

 tinental Shelf was more extensive, it was confined 

 almost entirely to the period during which these 

 stocks are available to fishermen, roughly June 

 or July through October. Knowledge of the 

 tunas of the shelf had been provided largely by 

 commercial and sjMrt fishermen and tlirough ex- 

 plorations conducted by the Bureau and tlie 

 Woods Hole Oceanographic Institution. 



Information on the hydrography of the oceanic 

 region also was examined and analyzed, and in- 

 quiries concerning sightings of tuna schools at the 

 surface were made with the U.S. Coast Guard 

 and the Woods Hole Oceanographic Institution. 

 Answers to these inquiries and the scarcity of 

 school sightings during a 1956 cruise of the Dela- 

 ware were discouraging and indicated that little 

 surface-fish life exists in the Gulf Stream area — 

 an indication that was later substantiated. 



In general the outlook was discouraging; how- 

 ever, there was one favorable sign. Mowbray 

 (1956) in the Bermuda area in the mid-1950's 

 had successfully used drifted longline gear to cap- 

 ture four species of tunas — bluefin, yellowfin, al- 

 bacore, and little tuna. These results suggested 



