about 500 gallons per minute) and terminate the experimentc 



With the methods which were used in the present workj, only 

 Oo7 percent of the skipjack, 27o3 percent of the frigate mackerel, and 

 25o0 percent of the large tunny were brought back aliveo In contrast, 

 the survival of small tunny was 82ol percent and of yellowfin, 6O0O 

 percento Doubtless survival for all species could be increased by 

 utilizing one or both of the suggestions made aboveo No particular 

 difficulty was experienced in handling and transporting small dolphin., 

 except in bringing them under control when they thrashed about violently 

 on decko 



Our experience with pond Noo 1 demonstrates the impracticality 

 of attempting to keep tuna in an enclosure with rough, jagged sides o 

 Not one fish of the several species of tuna which were introduced to 

 this pond survived for more than 3 days. Most of them^ bruised and 

 torn on the head and body from contact with the coralj died within a 

 few hours. Overhead lighting at night may have prolonged survival, 

 but it did not prevent deaths Dolphin and jacks j on the other hand, 

 were able to avoid the sides fairly well,, and eventually started to 

 feedo However s even among the established dolphin,, deaths occurred 

 occasionally from bruises and cuts suffered by contact with the walls 

 during the excitement of feedingo 



Our experience with the concrete tank shows that it is possible 

 to establish small tunny and yellowfin in a relatively small enclosurei 

 this is a distinct advantage in making observations during experimental 

 worko The success is attributed in part to the installation of white 

 corner baffles which not only led the fish in a circle but also clearly 

 delimited the tank boundarieso They seemed to be particularly important 

 during the critical prefeeding period„ Later^ the baffles became covered 

 with algal growth and were indistinguishable in color from the wallso 

 The overhead lighting probably helped alsOp although its contribution 

 to success was not investigated by removing the lights for fear of 

 causing the death of the fisho 



Small tunny and yellowfin were also successfully established 

 in the large pond NOo 5o Mortality during the prefeeding period 

 occurred mostly at night, and might be reduced by illuminating the pondo 



The small tunny became established m the tank and pond much 

 more readily than the yellowfin, and once a school had been established,, 

 new fish started to feed during the second day of confinements Of the 

 23 small tunny introduced, 18 (78o3 percent) became establishedo The 

 yellowfin,, on the other hand^ did not start to feed for several daysp 

 and mortality was high during the period of adjustmento Of the 27 

 yellowfin which were introduced to the tank and large pond, only 4 

 (l4o8 percent) started to feed and became establishedo 



Neither the tank nor the pond used for the retention of tuna 

 was of ideal size, shape^ and constructiono An ideal tank is en- 

 visioned as bowl-shapedj about 25 to 50 feet in diameter, and about 



18 



