(megalopae) when it was abundant locally. 

 T. obesus fed mostly on large deep- sea forms. 

 None of the tuna species seemed to compete 

 with each other for food. 



Zharov et al. (1964), who reviewed the tuna 

 fishery in the Atlantic Ocean, observed inter- 

 specific differences in feeding of tunas. Skip- 

 jack tuna fed on sardines, juvenile fish, squid 

 and other cephalopods, and small crustaceans; 

 yellowfin tuna fed on a variety of organisms, 

 from large plankton to fish; and little tuna fed 

 on relatively large fish, mainly sardine and 

 mackerel. 



Intraspecific differences in food composition 

 were noted. In the Mediterranean Sea, food of 

 adult bluefin tuna differed from that of the 

 young. Young bluefin tuna ate mostly small 

 crustaceans (60 percent), fish (20 percent), 

 mollusks (19 percent), and tunicates (1 per- 

 cent); most of the fish were larvae and juvenile 

 sardines and anchovies (Oren, Ben- Tuvia, and 

 Gottlieb, 1959). Sokolov (1967b) reported that 

 adult bluefin tuna fed mainly on fishes of vari- 

 ous sizes and species (anchovy, bonito, mac- 

 kerel, and small skipjack tuna). 



Seasonal and Diurnal Variations in Tuna Food 

 and Feeding 



Information on the seasonal aspect of the 

 food habits of tunas is given in only a few 

 papers. 



Sund and Richards (1967) found little geo- 

 graphical variation among tuna forage species 

 in the Gulf of Guinea, but a difference from 

 season to season. Anchoviella guineensis was 

 found only in stomachs of tunas taken during 

 the "cool" season. Trichiurus sp., unidentified 

 gonostomatids, Oxyporhamphus micropterus , 

 Atlanta sp., Illex illecebrosus , and a species 

 of unidentified salp were present only in sam- 

 ples taken during the "warm" season. The 

 seasonal distribution of other species couldnot 

 be delineated because of the large differences 

 among samples. 



Penrith (1963) reported almost no seasonal 

 variation in food taken by tuna off the Cape of 

 Good Hope--most species were consistently 

 present. Funchalia woodwardi was only occa- 

 sionally important to T. albacares and T. ala- 

 lunga , and the larvae of Jasus lalandii and 

 Plagusia chabrus were seasonally important 

 to T. alalunga and _T_. albacares. respectively. 

 Cephalopods were the only other important 

 food organism with pronounced changes in 

 seasonal availability. 



Information on the diurnal intensity of feed- 

 ing is very scarce in the literature on Atlantic 

 tunas. Sokolov (1967b) stated that yellowfin 

 tuna fed actively in the morning, slackly at 

 midday, and intensely again in the evening. 

 Talbot and Penrith (1963) made similar ob- 

 servations. Suarez-Caabro and Duarte-Bello 

 (1961) observed no differences in the food 

 volumes between morning and afternoon. 



LITERATURE CrTED 



(Papers reviewed are marked with asterisk in the literature cited; unmarked papers, which 

 are not concerned with tuna food in the Atlantic Ocean, were used as references but not 

 reviewed.) 



ALVERSON, FRANKLIN G. 



I960. Distribution of fishing effort and re- 

 sulting tuna catches from the Eastern 

 Tropical Pacific by quarters of the year, 

 1951-1958. Bull. Inter. -Amer. Trop. 

 Tuna Comm. 4: 319-446 (English and 

 Spanish). 

 *1963a. The food of yellowfin and skipjack 

 tunas in the Eastern Tropical Pacific 

 Ocean. Bull. Inter. -Amer. Trop. Tuna 

 Comm. 7: 295-396. (Incidental publi- 

 cation) 



1963b. Distribution of fishing effort and 

 resulting tuna catches from the Eastern 

 Tropical Pacific Ocean, by quarters of 

 the year, 1959-1962. Bull. Inter.- Amer. 

 Trop. Tuna Comm. 8: 319-379 (English 

 and Spanish). 



ANDERSON, WILLIAM W., and JACKW.GEH- 

 RINGER. 

 *1957a. Physical oceanographic, biological, 

 and chemical data, South Atlantic coast 

 of the United States, Theodore N. Gill 

 cruise 3. U.S. Fish Wildl. Serv., Spec. 

 Sci. Rep. Fish. 210, 208 pp. (Report on 

 data) 

 *1957b. Physical oceanographic, biological, 

 and chemical data, South Atlantic coast 

 of the United States, M/V Theodore N. 

 Gill cruise 4. U.S. Fish Wildl. Serv., 

 Spec. Sci. Rep. Fish. 234, 192 pp. (Re- 

 port on data) 

 *1958a. Physical oceanographic, biological, 

 and chemical data, South Atlantic coast 

 of the United States, M/V Theodore N. 

 Gill cruise 5. U.S. Fish Wildl. Serv., 



