Feeding Depths of Wild Caught Yellowfin Tuna Thunnus albacores Juveniles and Skipjack Tuna Katsuwonus pelamis in Sea Cages

This study was conducted in the lagoon of Mischief Reef, South China Sea to test the feasibility of feeding and rearing wild caught yellowfin tuna Thunnus albacares and skipjack tuna Katsuwonus pelamis juveniles in small, deep sea-water, cages. Fish started active feeding four days after transfer to the rearing cage. Initial feeding depth between yellowfin tuna and skipjack tuna was not significantly different (P > 0.05). The initial feeding depth for yellowfin tuna juveniles was 2.97±1.09 m, and skipjack tuna fed at 2.95 ± 0.77 m. After the 30 day rearing experiment specific growth rates of yellowfin tuna and skipjack tuna were: 0.25 ± 0.02 %/day and 0.32 ± 0.03%/day, respectively; survival rate of yellowfin tuna was 100%, and the survival rate of skipjack tuna was 82.6%. The estimated feed conversion ratio was 9.73 in this study. The results of this study provide practical data for culturing wild caught yellowfin tuna and skipjack tuna juveniles in sea cages.